Re: [PATCH 4/7] gpio: dwapb: Convert driver to using the GPIO-lib-based IRQ-chip
On Wed, Jul 29, 2020 at 06:10:24PM +0300, Andy Shevchenko wrote:
> On Wed, Jul 29, 2020 at 3:58 PM Serge Semin
> wrote:
> > On Mon, Jul 27, 2020 at 12:22:28AM +0200, Linus Walleij wrote:
>
> ...
>
> > Sorry for a delay with a response to this issue. I had to give it a more
> > thorough
> > thought since the problem is a bit more complex than it seemed originally.
> > As I
> > see it now It might be wrong to implement the cases 2) and 3), but 1) is
> > more
> > appropriate.
> >
> > First of all we need to note that GPIOlib framework provides the next
> > parameters
> > to describe the IRQ-chip:
> > gc->irq.num_parents - number of parental IRQ numbers.
> > gc->irq.parents[] - array of parental IRQ numbers.
> > *gc->irq.valid_mask - a mask of IRQ/GPIO lines describing a valid IRQ.
> > *gc->irq.map - mapping of hw IRQ/GPIO ID -> parental IRQ numbers.
> >
> > Using that set we can handle any case of linear and sparse parental IRQs.
> > Here
> > is how it can be implemented in the framework of DW APB GPIO controller.
> >
> > DW APB GPIO can be synthesized with two configs:
> > 1) Combined IRQ line (GPIO_INTR_IO == True),
> > 2) Multiple interrupt signals for each GPIO (GPIO_INTR_IO == False).
> >
> > Obviously the former case is trivial:
> >
> > IRQ_combined
> > __^
> >/_ _ _ _ _ ___ _\
> >|_|_|_|_|_|...|_| - GPIOs
> >
> > In that case
> > gc->irq.num_parents = 1;
> > gc->irq.parents[0] = IRQ_combined;
> > *gc->irq.valid_mask = GENMASK(ngpio - 1, 0); // This is done by the GPIOlib
> > core itself.
> >
> > The later one (when multiple interrupt signals are involved) can be a bit
> > more
> > complicated. It can be also split up into two cases:
> > 2a) One-on-one GPIO-IRQ mapping.
> > 2b) Sparse GPIO-IRQ mapping.
> >
> > It's straightforward to implement 2a):
> >
> >i1i2i3i4i5 ... iN
> > _ _ _ _ _ ___ _
> >|_|_|_|_|_|...|_| - GPIOs
> >
> > In that case
> > gc->irq.num_parents = ngpio;
> > gc->irq.parents[] = {i1, i2, i3, i4, i5, ... iN};
> > gc->irq.map = {i1, i2, i3, i4, i5, ... iN};
> > *gc->irq.valid_mask = GENMASK(ngpio - 1, 0);
> >
>
> This case puzzles me. Why is it not NULL and 0 and actually you handle
> everything as a nested case?
The code provided above is a sketch. Don't consider it literally. In reality
of course valid_mask will be not NULL, memory for which will be allocated by
the GPIOlib itself. The mask will be initialized by means of the
gc->irq.init_valid_mask() callback.
>
> > The complication starts when we get to implementing 2b):
> >
> >i1 xi3i4 x ... iN
> > _ _ _ _ _ ___ _
> >|_|_|_|_|_|...|_| - GPIOs
>
> So does this.
>
> Valid mask will define exactly GPIOs that are IRQs. So, we will handle
> only nested IRQs which are valid.
Right.
>
> > In order to cover this case we need to answer on two question.
> > Firstly how to get such platform config? I am not sure about ACPI, but
> > aside from straightforward platform_data-based setup such configuration
> > can be reached by setting up the "interrupts-extended" DT-property with
> > zeroed phandle.
> >
> > Ok, since it's possible to meet such platform config, we need to think
> > how to handle it and here is the second question. How to describe such
> > case in the framework of GPIOlib-IRQchip?
> >
> > So from my side it was wrong to set the sparse IRQs array to
> > gc->irq.parents. Instead I should have scanned the sparse IRQs array,
> > calculated the number of non-empty parental IRQs, created an array of linear
> > (non-sparse) IRQs, initialized *gc->irq.valid_mask in accordance with the
> > sparse parental IRQs array. In other words it was wrong to assume, that
> > each gc->irq.parents entry corresponds to the IRQ/GPIO line. The
> > gc->irq.parents
> > array just describes the parental IRQs and nothing else.
> >
> > Shortly speaking here is how the GPIOlib IRQchip parameters should be
> > initialized in this case:
> > gc->irq.num_parents - number of valid parental IRQs.
> > gc->irq.parents - non-sparse, linear array of valid IRQs.
> > *gc->irq.valid_mask - mask initialized by means of the
> > gc->irq.init_valid_mask()
> > callback, which indicates valid IRQ/GPIO IDs.
> > *gc->irq.map - sparse array of parental IRQ numbers (which I mistakenly
> > tried to
> > pass through the gc->irq.parents pointer).
> >
> > After that GPIOlib IRQchip should work just fine without need to be patched
> > in order to check whether the passed parental IRQs are valid or not.
> >
> > Please correct me if I am wrong in some aspects of the solution described
> > above.
> > I'll send a fix of the problem shortly.
>
> Maybe I'm missing something, but looks like you are solving the issue
> which is not so complex / doesn't exist.
As I see it now the problem was to provide a suitable config for GPIO-lib
IRQ-chip
so one would correctly perceive our DW APB GPIO-IRQ setup with
single/sparse/linear
IRQs. My point in the message before was to explain how that problem could be
solved
without
Re: [PATCH 4/7] gpio: dwapb: Convert driver to using the GPIO-lib-based IRQ-chip
On Wed, Jul 29, 2020 at 3:58 PM Serge Semin
wrote:
> On Mon, Jul 27, 2020 at 12:22:28AM +0200, Linus Walleij wrote:
...
> Sorry for a delay with a response to this issue. I had to give it a more
> thorough
> thought since the problem is a bit more complex than it seemed originally. As
> I
> see it now It might be wrong to implement the cases 2) and 3), but 1) is more
> appropriate.
>
> First of all we need to note that GPIOlib framework provides the next
> parameters
> to describe the IRQ-chip:
> gc->irq.num_parents - number of parental IRQ numbers.
> gc->irq.parents[] - array of parental IRQ numbers.
> *gc->irq.valid_mask - a mask of IRQ/GPIO lines describing a valid IRQ.
> *gc->irq.map - mapping of hw IRQ/GPIO ID -> parental IRQ numbers.
>
> Using that set we can handle any case of linear and sparse parental IRQs. Here
> is how it can be implemented in the framework of DW APB GPIO controller.
>
> DW APB GPIO can be synthesized with two configs:
> 1) Combined IRQ line (GPIO_INTR_IO == True),
> 2) Multiple interrupt signals for each GPIO (GPIO_INTR_IO == False).
>
> Obviously the former case is trivial:
>
> IRQ_combined
> __^
>/_ _ _ _ _ ___ _\
>|_|_|_|_|_|...|_| - GPIOs
>
> In that case
> gc->irq.num_parents = 1;
> gc->irq.parents[0] = IRQ_combined;
> *gc->irq.valid_mask = GENMASK(ngpio - 1, 0); // This is done by the GPIOlib
> core itself.
>
> The later one (when multiple interrupt signals are involved) can be a bit more
> complicated. It can be also split up into two cases:
> 2a) One-on-one GPIO-IRQ mapping.
> 2b) Sparse GPIO-IRQ mapping.
>
> It's straightforward to implement 2a):
>
>i1i2i3i4i5 ... iN
> _ _ _ _ _ ___ _
>|_|_|_|_|_|...|_| - GPIOs
>
> In that case
> gc->irq.num_parents = ngpio;
> gc->irq.parents[] = {i1, i2, i3, i4, i5, ... iN};
> gc->irq.map = {i1, i2, i3, i4, i5, ... iN};
> *gc->irq.valid_mask = GENMASK(ngpio - 1, 0);
>
This case puzzles me. Why is it not NULL and 0 and actually you handle
everything as a nested case?
> The complication starts when we get to implementing 2b):
>
>i1 xi3i4 x ... iN
> _ _ _ _ _ ___ _
>|_|_|_|_|_|...|_| - GPIOs
So does this.
Valid mask will define exactly GPIOs that are IRQs. So, we will handle
only nested IRQs which are valid.
> In order to cover this case we need to answer on two question.
> Firstly how to get such platform config? I am not sure about ACPI, but
> aside from straightforward platform_data-based setup such configuration
> can be reached by setting up the "interrupts-extended" DT-property with
> zeroed phandle.
>
> Ok, since it's possible to meet such platform config, we need to think
> how to handle it and here is the second question. How to describe such
> case in the framework of GPIOlib-IRQchip?
>
> So from my side it was wrong to set the sparse IRQs array to
> gc->irq.parents. Instead I should have scanned the sparse IRQs array,
> calculated the number of non-empty parental IRQs, created an array of linear
> (non-sparse) IRQs, initialized *gc->irq.valid_mask in accordance with the
> sparse parental IRQs array. In other words it was wrong to assume, that
> each gc->irq.parents entry corresponds to the IRQ/GPIO line. The
> gc->irq.parents
> array just describes the parental IRQs and nothing else.
>
> Shortly speaking here is how the GPIOlib IRQchip parameters should be
> initialized in this case:
> gc->irq.num_parents - number of valid parental IRQs.
> gc->irq.parents - non-sparse, linear array of valid IRQs.
> *gc->irq.valid_mask - mask initialized by means of the
> gc->irq.init_valid_mask()
> callback, which indicates valid IRQ/GPIO IDs.
> *gc->irq.map - sparse array of parental IRQ numbers (which I mistakenly tried
> to
> pass through the gc->irq.parents pointer).
>
> After that GPIOlib IRQchip should work just fine without need to be patched
> in order to check whether the passed parental IRQs are valid or not.
>
> Please correct me if I am wrong in some aspects of the solution described
> above.
> I'll send a fix of the problem shortly.
Maybe I'm missing something, but looks like you are solving the issue
which is not so complex / doesn't exist.
--
With Best Regards,
Andy Shevchenko
Re: [PATCH 4/7] gpio: dwapb: Convert driver to using the GPIO-lib-based IRQ-chip
On Mon, Jul 27, 2020 at 12:22:28AM +0200, Linus Walleij wrote:
> On Sat, Jul 25, 2020 at 1:03 AM Serge Semin
> wrote:
>
> > According to the DW APB GPIO databook it can be configured to provide
> > either a
> > combined IRQ line or multiple interrupt signals for each GPIO. It's up to
> > the platform which of those signals are connected to an embedded IRQ
> > controller. So I guess theoretically the array values can be sparse.
> >
> > Anyway now I see it's rather problematic. I didn't forget about the sparse
> > IRQs
> > array case. I just thought it would work out-of-box. Before getting your
> > comment
> > and digging deeper into the IRQ subsystem I had thought that it wasn't a
> > problem
> > passing invalid IRQ numbers to the irq_set_chained_handler_and_data()
> > especially
> > seeing zero IRQ number was supposed to be considered as invalid. That
> > method shall
> > just ignore the invalid IRQs since the method irq_to_desc() calling
> > radix_tree_lookup()
> > will fail to find a descriptor with invalid IRQ value and return NULL. So
> > after
> > getting a NULL irq_desc the method irq_set_chained_handler_and_data() would
> > have stopped setting the handler. But turns out it may work only for
> > CONFIG_SPARSE_IRQ. If that config isn't enabled, then a very first IRQ
> > descriptor will be returned for zero IRQ number. That descriptor will be
> > initialized with the passed parent_handler callback, which isn't what we
> > want.
>
> Ouch but different beahviour on the outside of the irqchip API depending
> on whether IRQs are sparse or not on some particular system seems to
> be a problem with irqchip reallty, if we wanna get to the bottom of things.
> (paging Marc)
>
> > So in order to fix the problem we could follow either of the next paths:
> > 1) Just make sure the passed IRQs array is not sparse for instance by
> > remapping
> >it to be linear.
> > 2) Move "if (gc->irq.parents[i]) irq_set_chained_handler_and_data()"
> > statement to the
> >gpiochip_add_irqchip() method.
> >
> > What to you think? Linus?
>
> What about (3) fixing irqchip?
>
> Else (2), making the code inside gpiolib be careful and skip over
> invalid IRQs.
Sorry for a delay with a response to this issue. I had to give it a more
thorough
thought since the problem is a bit more complex than it seemed originally. As I
see it now It might be wrong to implement the cases 2) and 3), but 1) is more
appropriate.
First of all we need to note that GPIOlib framework provides the next parameters
to describe the IRQ-chip:
gc->irq.num_parents - number of parental IRQ numbers.
gc->irq.parents[] - array of parental IRQ numbers.
*gc->irq.valid_mask - a mask of IRQ/GPIO lines describing a valid IRQ.
*gc->irq.map - mapping of hw IRQ/GPIO ID -> parental IRQ numbers.
Using that set we can handle any case of linear and sparse parental IRQs. Here
is how it can be implemented in the framework of DW APB GPIO controller.
DW APB GPIO can be synthesized with two configs:
1) Combined IRQ line (GPIO_INTR_IO == True),
2) Multiple interrupt signals for each GPIO (GPIO_INTR_IO == False).
Obviously the former case is trivial:
IRQ_combined
__^
/_ _ _ _ _ ___ _\
|_|_|_|_|_|...|_| - GPIOs
In that case
gc->irq.num_parents = 1;
gc->irq.parents[0] = IRQ_combined;
*gc->irq.valid_mask = GENMASK(ngpio - 1, 0); // This is done by the GPIOlib
core itself.
The later one (when multiple interrupt signals are involved) can be a bit more
complicated. It can be also split up into two cases:
2a) One-on-one GPIO-IRQ mapping.
2b) Sparse GPIO-IRQ mapping.
It's straightforward to implement 2a):
i1i2i3i4i5 ... iN
_ _ _ _ _ ___ _
|_|_|_|_|_|...|_| - GPIOs
In that case
gc->irq.num_parents = ngpio;
gc->irq.parents[] = {i1, i2, i3, i4, i5, ... iN};
gc->irq.map = {i1, i2, i3, i4, i5, ... iN};
*gc->irq.valid_mask = GENMASK(ngpio - 1, 0);
The complication starts when we get to implementing 2b):
i1 xi3i4 x ... iN
_ _ _ _ _ ___ _
|_|_|_|_|_|...|_| - GPIOs
In order to cover this case we need to answer on two question.
Firstly how to get such platform config? I am not sure about ACPI, but
aside from straightforward platform_data-based setup such configuration
can be reached by setting up the "interrupts-extended" DT-property with
zeroed phandle.
Ok, since it's possible to meet such platform config, we need to think
how to handle it and here is the second question. How to describe such
case in the framework of GPIOlib-IRQchip?
So from my side it was wrong to set the sparse IRQs array to
gc->irq.parents. Instead I should have scanned the sparse IRQs array,
calculated the number of non-empty parental IRQs, created an array of linear
(non-sparse) IRQs, initialized *gc->irq.valid_mask in accordance with the
sparse parental IRQs array. In other words it was wrong to assume, that
each gc->irq.parents entry corresponds to the IRQ/GPIO line. The gc->irq.parents
array just describes the parental IRQs and nothing else.
Re: [PATCH 4/7] gpio: dwapb: Convert driver to using the GPIO-lib-based IRQ-chip
On Tue, Jul 28, 2020 at 11:18 AM Linus Walleij wrote: > > On Mon, Jul 27, 2020 at 11:50 PM Serge Semin > wrote: > > > It turns out my "mostly" was wrong in this matter. It's 4 out of 17 patches, > > which make the initialization in the same order as mine: > > I'll think about fixing them up to all look the same at some point > if noone beats me to it. Sorry for the mess, I was just hacking > along to get this work item finalized. I have sent three patches (two updates according to above matter and one is a fix on top of your template clean up I missed myself). -- With Best Regards, Andy Shevchenko
Re: [PATCH 4/7] gpio: dwapb: Convert driver to using the GPIO-lib-based IRQ-chip
On Mon, Jul 27, 2020 at 11:50 PM Serge Semin wrote: > It turns out my "mostly" was wrong in this matter. It's 4 out of 17 patches, > which make the initialization in the same order as mine: I'll think about fixing them up to all look the same at some point if noone beats me to it. Sorry for the mess, I was just hacking along to get this work item finalized. Yours, Linus Walleij
Re: [PATCH 4/7] gpio: dwapb: Convert driver to using the GPIO-lib-based IRQ-chip
On Sat, Jul 25, 2020 at 03:12:49PM +0300, Andy Shevchenko wrote: > On Sat, Jul 25, 2020 at 2:03 AM Serge Semin > wrote: > > On Thu, Jul 23, 2020 at 01:03:17PM +0300, Andy Shevchenko wrote: > > > On Thu, Jul 23, 2020 at 04:38:55AM +0300, Serge Semin wrote: ... > > > > + /* This will let us handle the parent IRQ in the driver */ > > > > + girq->parents = NULL; > > > > + girq->num_parents = 0; > > > > + girq->parent_handler = NULL; > > > > Shan't we do this before request_irq() call (at least for consistency > > > with the > > > rest of the drivers)? > > > > Technically we shan't. Please elaborate which drivers you are referring to? > > All of them? Recent patches for IRQ chip template do something like > > girq = &...; > girq->foo = bar; > ... > ret = request_irq(...); > > ...and here no more girq->baz = gaz; lines. > > > Even the recent Linus' series "Use irqchip template" mostly does it in the > > same order. > > Funny, that's what I;m referring to. It turns out my "mostly" was wrong in this matter. It's 4 out of 17 patches, which make the initialization in the same order as mine: drivers/gpio/gpio-max732x.c drivers/gpio/gpio-pca953x.c drivers/gpio/gpio-pcf857x.c drivers/gpio/gpio-adp5588.c while the rest of them does it in the order suggested by you: drivers/gpio/gpio-pci-idio-16.c drivers/gpio/gpio-pcie-idio-24.c drivers/gpio/gpio-104-idio-16.c drivers/gpio/gpio-104-dio-48e.c drivers/gpio/gpio-ws16c48.c drivers/gpio/gpio-rcar.c drivers/gpio/gpio-wcove.c drivers/pinctrl/pinctrl-amd.c drivers/gpio/gpio-crystalcove.c drivers/pinctrl/pinctrl-mcp23s08.c drivers/pinctrl/pinctrl-sx150x.c drivers/pinctrl/pinctrl-stmfx.c drivers/gpio/gpio-tc3589x.c Then, let's use the same order here as the most of the drivers do just for consistency. -Sergey > > -- > With Best Regards, > Andy Shevchenko
Re: [PATCH 4/7] gpio: dwapb: Convert driver to using the GPIO-lib-based IRQ-chip
On Sat, Jul 25, 2020 at 1:03 AM Serge Semin wrote: > According to the DW APB GPIO databook it can be configured to provide either a > combined IRQ line or multiple interrupt signals for each GPIO. It's up to > the platform which of those signals are connected to an embedded IRQ > controller. So I guess theoretically the array values can be sparse. > > Anyway now I see it's rather problematic. I didn't forget about the sparse > IRQs > array case. I just thought it would work out-of-box. Before getting your > comment > and digging deeper into the IRQ subsystem I had thought that it wasn't a > problem > passing invalid IRQ numbers to the irq_set_chained_handler_and_data() > especially > seeing zero IRQ number was supposed to be considered as invalid. That method > shall > just ignore the invalid IRQs since the method irq_to_desc() calling > radix_tree_lookup() > will fail to find a descriptor with invalid IRQ value and return NULL. So > after > getting a NULL irq_desc the method irq_set_chained_handler_and_data() would > have stopped setting the handler. But turns out it may work only for > CONFIG_SPARSE_IRQ. If that config isn't enabled, then a very first IRQ > descriptor will be returned for zero IRQ number. That descriptor will be > initialized with the passed parent_handler callback, which isn't what we want. Ouch but different beahviour on the outside of the irqchip API depending on whether IRQs are sparse or not on some particular system seems to be a problem with irqchip reallty, if we wanna get to the bottom of things. (paging Marc) > So in order to fix the problem we could follow either of the next paths: > 1) Just make sure the passed IRQs array is not sparse for instance by > remapping >it to be linear. > 2) Move "if (gc->irq.parents[i]) irq_set_chained_handler_and_data()" > statement to the >gpiochip_add_irqchip() method. > > What to you think? Linus? What about (3) fixing irqchip? Else (2), making the code inside gpiolib be careful and skip over invalid IRQs. Yours, Linus Walleij
Re: [PATCH 4/7] gpio: dwapb: Convert driver to using the GPIO-lib-based IRQ-chip
On Sat, Jul 25, 2020 at 2:03 AM Serge Semin
wrote:
> On Thu, Jul 23, 2020 at 01:03:17PM +0300, Andy Shevchenko wrote:
> > On Thu, Jul 23, 2020 at 04:38:55AM +0300, Serge Semin wrote:
...
> > > 5) Manually select a proper IRQ flow handler directly in the
> > > irq_set_type() callback by calling irq_set_handler_locked() method, since
> > > an ordinary (not Generic) irq_chip descriptor is now utilized.
> > Can you also emphasize that this make no regression to the 6a2f4b7dadd5
> > ("gpio:
> > dwapb: use a second irq chip")?
>
> In fact I don't really see why that commit had been accepted in the first
> place.
> Both level and edge triggered IRQ types are implemented by means of the same
> callbacks and the same registers. The only handy thing in our case is the IRQ
> flow handler setting in accordance with the requested IRQ type, but that
> could be done by just calling irq_set_handler_locked() method without
> two-types
> complication. The commit log says: "So we can have at runtime two users where
> one is using edge and the other level." which isn't really correct since if
> an IRQ
> line is shared it can only be requested with the same trigger flags (see the
> inline comments in the __setup_irq() method definition). If an IRQ line isn't
> shared, then there can't be more than one user.
>
> Am I missing something?
I didn't investigate myself, but probably it's a history of changes
you are missing.
That said, in time when the above mentioned commit was made there was
no clear approach like we have nowadays.
But I might be mistaken.
In any case, just add a (small) remark that you were aware of that
change and do not see any problems while doing yours.
> > (And I hope you have means to test that scenario, because in my case I have
> > only one IRQ and it's actually as input from other GPIO IRQ chip).
>
> Alas I have DW APB GPIO with a single IRQ line attached too, so I can't test
> the
> hierarchical case, but only the cascaded one.
Alas.
...
> > I like the idea, but is it possible to split this?
>
> Yeah, 6) and 7) could be unpinned to dedicated patches. Thanks for noticing
> this. I'll do that. But leaving the changes described before and not applying
> 8)
> will produce buildable but not working driver. So I'd prefer to leave 8) here.
I see. Yes, we have to have compile time *and* run-time bisectability in place.
...
> > > + /*
> > > +* If more than one IRQ line is specified then try to
> > > +* initialize the hierarchical interrupts. Otherwise it's
> > > +* a simple cascaded case with a common IRQ signal.
> > > +*/
> > > + girq->num_parents = pp->irq[1] ? pp->ngpio : 1;
> >
>
> > Can it be sparse in the array? (It's actually the main point why I went with
> > memchr_inv() instead of doing something like above)
>
> According to the DW APB GPIO databook it can be configured to provide either a
> combined IRQ line or multiple interrupt signals for each GPIO. It's up to
> the platform which of those signals are connected to an embedded IRQ
> controller. So I guess theoretically the array values can be sparse.
>
> Anyway now I see it's rather problematic. I didn't forget about the sparse
> IRQs
> array case. I just thought it would work out-of-box. Before getting your
> comment
> and digging deeper into the IRQ subsystem I had thought that it wasn't a
> problem
> passing invalid IRQ numbers to the irq_set_chained_handler_and_data()
> especially
> seeing zero IRQ number was supposed to be considered as invalid. That method
> shall
> just ignore the invalid IRQs since the method irq_to_desc() calling
> radix_tree_lookup()
> will fail to find a descriptor with invalid IRQ value and return NULL. So
> after
> getting a NULL irq_desc the method irq_set_chained_handler_and_data() would
> have stopped setting the handler. But turns out it may work only for
> CONFIG_SPARSE_IRQ. If that config isn't enabled, then a very first IRQ
> descriptor will be returned for zero IRQ number. That descriptor will be
> initialized with the passed parent_handler callback, which isn't what we want.
>
> So in order to fix the problem we could follow either of the next paths:
> 1) Just make sure the passed IRQs array is not sparse for instance by
> remapping
>it to be linear.
> 2) Move "if (gc->irq.parents[i]) irq_set_chained_handler_and_data()"
> statement to the
>gpiochip_add_irqchip() method.
>
> What to you think? Linus?
I am okay with either that Linus will like.
...
> > > + /* This will let us handle the parent IRQ in the driver */
> > > + girq->parents = NULL;
> > > + girq->num_parents = 0;
> > > + girq->parent_handler = NULL;
> > Shan't we do this before request_irq() call (at least for consistency with
> > the
> > rest of the drivers)?
>
> Technically we shan't. Please elaborate which drivers you are referring to?
All of them? Recent patches for IRQ chip template do something like
Re: [PATCH 4/7] gpio: dwapb: Convert driver to using the GPIO-lib-based IRQ-chip
On Thu, Jul 23, 2020 at 05:08:15PM +0300, Andy Shevchenko wrote:
> On Thu, Jul 23, 2020 at 04:38:55AM +0300, Serge Semin wrote:
> > GPIO-lib provides a ready-to-use interface to initialize an IRQ-chip on
> > top of a GPIO chip. It's better from maintainability and readability
> > point of view to use one instead of supporting a hand-written Generic
> > IRQ-chip-based implementation. Moreover the new implementation won't
> > cause much functional overhead but will provide a cleaner driver code.
> > All of that makes the DW APB GPIO driver conversion pretty much justified
> > especially seeing a tendency of the other GPIO drivers getting converted
> > too.
> >
> > Here is what we do in the framework of this commit to convert the driver
> > to using the GPIO-lib-based IRQ-chip interface:
> > 1) IRQ ack, mask and unmask callbacks are locally defined instead of
> > using the Generic IRQ-chip ones.
> > 2) An irq_chip structure instance is embedded into the dwapb_gpio
> > private data. Note we can't have a static instance of that structure since
> > GPIO-lib will add some hooks into it by calling gpiochip_set_irq_hooks().
> > A warning about that would have been printed by the GPIO-lib code if we
> > used a single irq_chip structure instance for multiple DW APB GPIO
> > controllers.
> > 3) Initialize the gpio_irq_chip structure embedded into the gpio_chip
> > descriptor. By default there is no IRQ enabled so any event raised will be
> > handled by the handle_bad_irq() IRQ flow handler. If DW APB GPIO IP-core
> > is synthesized to have non-shared reference IRQ-lines, then as before the
> > hierarchical and cascaded cases are distinguished by checking how many
> > parental IRQs are defined. (Note irq_set_chained_handler_and_data() won't
> > initialize IRQs, which descriptors couldn't be found.) If DW APB GPIO IP
> > is used on a platform with shared IRQ line, then we simply won't let the
> > GPIO-lib to initialize the parental IRQs, but will handle them locally in
> > the driver.
> > 4) Discard linear IRQ-domain and Generic IRQ-chip initialization, since
> > GPIO-lib IRQ-chip interface will create a new domain and accept a standard
> > IRQ-chip structure pointer based on the setting we provided in the
> > gpio_irq_chip structure.
> > 5) Manually select a proper IRQ flow handler directly in the
> > irq_set_type() callback by calling irq_set_handler_locked() method, since
> > an ordinary (not Generic) irq_chip descriptor is now utilized.
> > 6) Discard the custom GPIO-to-IRQ mapping function since GPIO-lib defines
> > the standard method gpiochip_to_irq(), which will be used anyway no matter
> > whether the custom to_irq callback is specified or not.
> > 7) Discard the acpi_gpiochip_{request,free}_interrupts()
> > invocations, since they will be called from
> > gpiochip_add_irqchip()/gpiochip_irqchip_remove() anyway.
> > 8) Alter CONFIG_GPIO_DWAPB kernel config to select
> > CONFIG_GPIOLIB_IRQCHIP instead of CONFIG_GENERIC_IRQ_CHIP.
>
>
> ...
>
> One more thing...
>
> > static u32 dwapb_do_irq(struct dwapb_gpio *gpio)
> > {
> > + struct gpio_chip *gc = >ports[0].gc;
> > unsigned long irq_status;
> > irq_hw_number_t hwirq;
> >
> > irq_status = dwapb_read(gpio, GPIO_INTSTATUS);
> > for_each_set_bit(hwirq, _status, 32) {
> > - int gpio_irq = irq_find_mapping(gpio->domain, hwirq);
> > + int gpio_irq = gc->to_irq(gc, hwirq);
>
> Very, very few do this.
> Can we stick with the original one?
> (See plenty of other examples in the GPIO / pin control subsystems.
You are right. After more thorough studying the IRQ-domain code I've found out
that irq_domain_add_simple() provides the on-the-fly mapping creation. We
don't have to call irq_create_mapping() first before using irq_find_mapping().
So the irq_find_mapping(gc->irq.domain, hwirq) method can be freely called here
the same way as the most of the GPIO drivers do. Thanks for noticing this.
-Sergey
>
> > u32 irq_type = irq_get_trigger_type(gpio_irq);
> >
> > generic_handle_irq(gpio_irq);
>
>
> > }
>
> --
> With Best Regards,
> Andy Shevchenko
>
>
Re: [PATCH 4/7] gpio: dwapb: Convert driver to using the GPIO-lib-based IRQ-chip
On Thu, Jul 23, 2020 at 01:03:17PM +0300, Andy Shevchenko wrote:
> On Thu, Jul 23, 2020 at 04:38:55AM +0300, Serge Semin wrote:
> > GPIO-lib provides a ready-to-use interface to initialize an IRQ-chip on
> > top of a GPIO chip. It's better from maintainability and readability
> > point of view to use one instead of supporting a hand-written Generic
> > IRQ-chip-based implementation. Moreover the new implementation won't
> > cause much functional overhead but will provide a cleaner driver code.
> > All of that makes the DW APB GPIO driver conversion pretty much justified
> > especially seeing a tendency of the other GPIO drivers getting converted
> > too.
> >
> > Here is what we do in the framework of this commit to convert the driver
> > to using the GPIO-lib-based IRQ-chip interface:
> > 1) IRQ ack, mask and unmask callbacks are locally defined instead of
> > using the Generic IRQ-chip ones.
> > 2) An irq_chip structure instance is embedded into the dwapb_gpio
> > private data. Note we can't have a static instance of that structure since
> > GPIO-lib will add some hooks into it by calling gpiochip_set_irq_hooks().
> > A warning about that would have been printed by the GPIO-lib code if we
> > used a single irq_chip structure instance for multiple DW APB GPIO
> > controllers.
> > 3) Initialize the gpio_irq_chip structure embedded into the gpio_chip
> > descriptor. By default there is no IRQ enabled so any event raised will be
> > handled by the handle_bad_irq() IRQ flow handler. If DW APB GPIO IP-core
> > is synthesized to have non-shared reference IRQ-lines, then as before the
> > hierarchical and cascaded cases are distinguished by checking how many
> > parental IRQs are defined. (Note irq_set_chained_handler_and_data() won't
> > initialize IRQs, which descriptors couldn't be found.) If DW APB GPIO IP
> > is used on a platform with shared IRQ line, then we simply won't let the
> > GPIO-lib to initialize the parental IRQs, but will handle them locally in
> > the driver.
> > 4) Discard linear IRQ-domain and Generic IRQ-chip initialization, since
> > GPIO-lib IRQ-chip interface will create a new domain and accept a standard
> > IRQ-chip structure pointer based on the setting we provided in the
> > gpio_irq_chip structure.
> > 5) Manually select a proper IRQ flow handler directly in the
> > irq_set_type() callback by calling irq_set_handler_locked() method, since
> > an ordinary (not Generic) irq_chip descriptor is now utilized.
>
> Can you also emphasize that this make no regression to the 6a2f4b7dadd5
> ("gpio:
> dwapb: use a second irq chip")?
In fact I don't really see why that commit had been accepted in the first place.
Both level and edge triggered IRQ types are implemented by means of the same
callbacks and the same registers. The only handy thing in our case is the IRQ
flow handler setting in accordance with the requested IRQ type, but that
could be done by just calling irq_set_handler_locked() method without two-types
complication. The commit log says: "So we can have at runtime two users where
one is using edge and the other level." which isn't really correct since if an
IRQ
line is shared it can only be requested with the same trigger flags (see the
inline comments in the __setup_irq() method definition). If an IRQ line isn't
shared, then there can't be more than one user.
Am I missing something?
>
> (And I hope you have means to test that scenario, because in my case I have
> only one IRQ and it's actually as input from other GPIO IRQ chip).
Alas I have DW APB GPIO with a single IRQ line attached too, so I can't test the
hierarchical case, but only the cascaded one.
>
> > 6) Discard the custom GPIO-to-IRQ mapping function since GPIO-lib defines
> > the standard method gpiochip_to_irq(), which will be used anyway no matter
> > whether the custom to_irq callback is specified or not.
> > 7) Discard the acpi_gpiochip_{request,free}_interrupts()
> > invocations, since they will be called from
> > gpiochip_add_irqchip()/gpiochip_irqchip_remove() anyway.
> > 8) Alter CONFIG_GPIO_DWAPB kernel config to select
> > CONFIG_GPIOLIB_IRQCHIP instead of CONFIG_GENERIC_IRQ_CHIP.
>
> I like the idea, but is it possible to split this?
Yeah, 6) and 7) could be unpinned to dedicated patches. Thanks for noticing
this. I'll do that. But leaving the changes described before and not applying 8)
will produce buildable but not working driver. So I'd prefer to leave 8) here.
>
> ...
>
> > static int dwapb_irq_set_type(struct irq_data *d, u32 type)
> > {
> > - struct irq_chip_generic *igc = irq_data_get_irq_chip_data(d);
> > - struct dwapb_gpio *gpio = igc->private;
> > - struct gpio_chip *gc = >ports[0].gc;
> > + struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
> > + struct dwapb_gpio *gpio = to_dwapb_gpio(gc);
> > irq_hw_number_t bit = irqd_to_hwirq(d);
> > unsigned long level, polarity, flags;
> > + irq_flow_handler_t handler;
> >
> > if (type & ~IRQ_TYPE_SENSE_MASK)
Re: [PATCH 4/7] gpio: dwapb: Convert driver to using the GPIO-lib-based IRQ-chip
On Thu, Jul 23, 2020 at 04:38:55AM +0300, Serge Semin wrote:
> GPIO-lib provides a ready-to-use interface to initialize an IRQ-chip on
> top of a GPIO chip. It's better from maintainability and readability
> point of view to use one instead of supporting a hand-written Generic
> IRQ-chip-based implementation. Moreover the new implementation won't
> cause much functional overhead but will provide a cleaner driver code.
> All of that makes the DW APB GPIO driver conversion pretty much justified
> especially seeing a tendency of the other GPIO drivers getting converted
> too.
>
> Here is what we do in the framework of this commit to convert the driver
> to using the GPIO-lib-based IRQ-chip interface:
> 1) IRQ ack, mask and unmask callbacks are locally defined instead of
> using the Generic IRQ-chip ones.
> 2) An irq_chip structure instance is embedded into the dwapb_gpio
> private data. Note we can't have a static instance of that structure since
> GPIO-lib will add some hooks into it by calling gpiochip_set_irq_hooks().
> A warning about that would have been printed by the GPIO-lib code if we
> used a single irq_chip structure instance for multiple DW APB GPIO
> controllers.
> 3) Initialize the gpio_irq_chip structure embedded into the gpio_chip
> descriptor. By default there is no IRQ enabled so any event raised will be
> handled by the handle_bad_irq() IRQ flow handler. If DW APB GPIO IP-core
> is synthesized to have non-shared reference IRQ-lines, then as before the
> hierarchical and cascaded cases are distinguished by checking how many
> parental IRQs are defined. (Note irq_set_chained_handler_and_data() won't
> initialize IRQs, which descriptors couldn't be found.) If DW APB GPIO IP
> is used on a platform with shared IRQ line, then we simply won't let the
> GPIO-lib to initialize the parental IRQs, but will handle them locally in
> the driver.
> 4) Discard linear IRQ-domain and Generic IRQ-chip initialization, since
> GPIO-lib IRQ-chip interface will create a new domain and accept a standard
> IRQ-chip structure pointer based on the setting we provided in the
> gpio_irq_chip structure.
> 5) Manually select a proper IRQ flow handler directly in the
> irq_set_type() callback by calling irq_set_handler_locked() method, since
> an ordinary (not Generic) irq_chip descriptor is now utilized.
> 6) Discard the custom GPIO-to-IRQ mapping function since GPIO-lib defines
> the standard method gpiochip_to_irq(), which will be used anyway no matter
> whether the custom to_irq callback is specified or not.
> 7) Discard the acpi_gpiochip_{request,free}_interrupts()
> invocations, since they will be called from
> gpiochip_add_irqchip()/gpiochip_irqchip_remove() anyway.
> 8) Alter CONFIG_GPIO_DWAPB kernel config to select
> CONFIG_GPIOLIB_IRQCHIP instead of CONFIG_GENERIC_IRQ_CHIP.
...
One more thing...
> static u32 dwapb_do_irq(struct dwapb_gpio *gpio)
> {
> + struct gpio_chip *gc = >ports[0].gc;
> unsigned long irq_status;
> irq_hw_number_t hwirq;
>
> irq_status = dwapb_read(gpio, GPIO_INTSTATUS);
> for_each_set_bit(hwirq, _status, 32) {
> - int gpio_irq = irq_find_mapping(gpio->domain, hwirq);
> + int gpio_irq = gc->to_irq(gc, hwirq);
Very, very few do this.
Can we stick with the original one?
(See plenty of other examples in the GPIO / pin control subsystems.
> u32 irq_type = irq_get_trigger_type(gpio_irq);
>
> generic_handle_irq(gpio_irq);
> }
--
With Best Regards,
Andy Shevchenko
Re: [PATCH 4/7] gpio: dwapb: Convert driver to using the GPIO-lib-based IRQ-chip
Hi Serge, On Thu, Jul 23, 2020 at 3:39 AM Serge Semin wrote: > GPIO-lib provides a ready-to-use interface to initialize an IRQ-chip on > top of a GPIO chip. It's better from maintainability and readability > point of view to use one instead of supporting a hand-written Generic > IRQ-chip-based implementation. Moreover the new implementation won't > cause much functional overhead but will provide a cleaner driver code. > All of that makes the DW APB GPIO driver conversion pretty much justified > especially seeing a tendency of the other GPIO drivers getting converted > too. Needless to say I am a big fan of this patch. It's what I wanted to do with the driver but was afraid to dry-code. Please look into the minor nits pointed out by Andy and respin, I really want to apply this patch set. Thanks, Linus Walleij
Re: [PATCH 4/7] gpio: dwapb: Convert driver to using the GPIO-lib-based IRQ-chip
On Thu, Jul 23, 2020 at 04:38:55AM +0300, Serge Semin wrote:
> GPIO-lib provides a ready-to-use interface to initialize an IRQ-chip on
> top of a GPIO chip. It's better from maintainability and readability
> point of view to use one instead of supporting a hand-written Generic
> IRQ-chip-based implementation. Moreover the new implementation won't
> cause much functional overhead but will provide a cleaner driver code.
> All of that makes the DW APB GPIO driver conversion pretty much justified
> especially seeing a tendency of the other GPIO drivers getting converted
> too.
>
> Here is what we do in the framework of this commit to convert the driver
> to using the GPIO-lib-based IRQ-chip interface:
> 1) IRQ ack, mask and unmask callbacks are locally defined instead of
> using the Generic IRQ-chip ones.
> 2) An irq_chip structure instance is embedded into the dwapb_gpio
> private data. Note we can't have a static instance of that structure since
> GPIO-lib will add some hooks into it by calling gpiochip_set_irq_hooks().
> A warning about that would have been printed by the GPIO-lib code if we
> used a single irq_chip structure instance for multiple DW APB GPIO
> controllers.
> 3) Initialize the gpio_irq_chip structure embedded into the gpio_chip
> descriptor. By default there is no IRQ enabled so any event raised will be
> handled by the handle_bad_irq() IRQ flow handler. If DW APB GPIO IP-core
> is synthesized to have non-shared reference IRQ-lines, then as before the
> hierarchical and cascaded cases are distinguished by checking how many
> parental IRQs are defined. (Note irq_set_chained_handler_and_data() won't
> initialize IRQs, which descriptors couldn't be found.) If DW APB GPIO IP
> is used on a platform with shared IRQ line, then we simply won't let the
> GPIO-lib to initialize the parental IRQs, but will handle them locally in
> the driver.
> 4) Discard linear IRQ-domain and Generic IRQ-chip initialization, since
> GPIO-lib IRQ-chip interface will create a new domain and accept a standard
> IRQ-chip structure pointer based on the setting we provided in the
> gpio_irq_chip structure.
> 5) Manually select a proper IRQ flow handler directly in the
> irq_set_type() callback by calling irq_set_handler_locked() method, since
> an ordinary (not Generic) irq_chip descriptor is now utilized.
Can you also emphasize that this make no regression to the 6a2f4b7dadd5 ("gpio:
dwapb: use a second irq chip")?
(And I hope you have means to test that scenario, because in my case I have
only one IRQ and it's actually as input from other GPIO IRQ chip).
> 6) Discard the custom GPIO-to-IRQ mapping function since GPIO-lib defines
> the standard method gpiochip_to_irq(), which will be used anyway no matter
> whether the custom to_irq callback is specified or not.
> 7) Discard the acpi_gpiochip_{request,free}_interrupts()
> invocations, since they will be called from
> gpiochip_add_irqchip()/gpiochip_irqchip_remove() anyway.
> 8) Alter CONFIG_GPIO_DWAPB kernel config to select
> CONFIG_GPIOLIB_IRQCHIP instead of CONFIG_GENERIC_IRQ_CHIP.
I like the idea, but is it possible to split this?
...
> static int dwapb_irq_set_type(struct irq_data *d, u32 type)
> {
> - struct irq_chip_generic *igc = irq_data_get_irq_chip_data(d);
> - struct dwapb_gpio *gpio = igc->private;
> - struct gpio_chip *gc = >ports[0].gc;
> + struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
> + struct dwapb_gpio *gpio = to_dwapb_gpio(gc);
> irq_hw_number_t bit = irqd_to_hwirq(d);
> unsigned long level, polarity, flags;
> + irq_flow_handler_t handler;
>
> if (type & ~IRQ_TYPE_SENSE_MASK)
> return -EINVAL;
> @@ -274,26 +304,31 @@ static int dwapb_irq_set_type(struct irq_data *d, u32
> type)
> case IRQ_TYPE_EDGE_BOTH:
> level |= BIT(bit);
> dwapb_toggle_trigger(gpio, bit);
> + handler = handle_edge_irq;
> break;
> case IRQ_TYPE_EDGE_RISING:
> level |= BIT(bit);
> polarity |= BIT(bit);
> + handler = handle_edge_irq;
> break;
> case IRQ_TYPE_EDGE_FALLING:
> level |= BIT(bit);
> polarity &= ~BIT(bit);
> + handler = handle_edge_irq;
> break;
> case IRQ_TYPE_LEVEL_HIGH:
> level &= ~BIT(bit);
> polarity |= BIT(bit);
> + handler = handle_level_irq;
> break;
> case IRQ_TYPE_LEVEL_LOW:
> level &= ~BIT(bit);
> polarity &= ~BIT(bit);
> + handler = handle_level_irq;
> break;
> }
>
> - irq_setup_alt_chip(d, type);
> + irq_set_handler_locked(d, handler);
Can we rather do like other GPIO IRQ chip implementations are doing, i.e.
instead of repeating same handler in each branch, use one conditional:
if (type & IRQ_TYPE_LEVEL_MASK) {
...
