RE: [PATCH] ARM: SAMSUNG: Save/restore GPIO drive strength across suspend/resume
Thomas Abraham wrote at Monday, November 14, 2011 12:37 PM: ... > I am not sure how this works, but with dynamic transitioning, will it > be possible to program the pinmux registers dynamically when a > driver/controller decides to idle for sometime and come back up again > (not a system wide suspend-resume cycle). There might be a need for > the driver to inform the pinmux subsystem of this case and allow the > pinmux subsystem to re-program pinmux registers as required. Well, such a feature doesn't exist yet. But, I envisaged extending the existing: pmx = pinmux_get() pinmux_enable(pmx) ... pinmux_disable(pmx) pinmux_put(pmx) to something like: pmx = pinmux_get(active) pinmux_enable(pmx) ... pinmux_switch(suspend) ... pinmux_switch(active) ... pinmux_disable(pmx) pinmux_put(pmx) (I think LinusW proposed an alternative a while back last time we talked about this) This has received only limited discussion though, and there are probably many gotchas to think through; I imagine any such feature is a way off. -- nvpublic -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] ARM: SAMSUNG: Save/restore GPIO drive strength across suspend/resume
On 15 November 2011 00:30, Stephen Warren wrote:
> Thomas Abraham wrote at Monday, November 14, 2011 6:57 AM:
>> On 12 November 2011 16:30, Linus Walleij wrote:
>> > On Sat, Nov 12, 2011 at 6:01 AM, Inderpal Singh
>> > wrote:
>> >
>> >> GPIO driver strength settings are not preserved across suspend/resume
>> >> for s5pc100, s5pv210 and Exynos platforms which has been the cause of
>> >> mmc/sd card read/write failures after resume. Fix this by saving and
>> >> restoring the GPIO driver strength register settings across
>> >> suspend/resume.
>> >>
>> >> Signed-off-by: Inderpal Singh
>> >
>> > On a related theme: I am thinking about how to support preserving
>> > drive strength (etc) across suspend/resume and deepsleep in the
>> > pincontrol subsystem.
>> >
>> > Currently I am playing with the idea to let pin groups have states,
>> > as the different configurations seem to be 90% or so about very
>> > specific sleep modes, so say:
>> >
>> > pinconf_set_group_state("mmcgroup", PINCONF_STATE_ACTIVE);
>> > pinconf_set_group_state("mmcgroup", PINCONF_STATE_SUSPENDED);
>> > pinconf_set_group_state("mmcgroup", PINCONF_STATE_SLEEP);
>>
>>
>> The API name suggests that power state is set based on a pin group.
>> For a driver, the following could be convenient as the driver transits
>> through various power management states.
>>
>> struct pinmux pmx;
>> pmx = pinmux_get(dev, "i2c0");
>>
>> [...]
>>
>> pinmux_set_state(pmx, PINCONF_STATE_SLEEP);
>> [...]
>> pinmux_set_state(pmx, PINCONF_STATE_ACTIVE);
>
> That seems a more consistent driver-oriented API, yes.
>
> I'd of course lean towards adding the pin config data into the mapping
> table, and using the existing feature struct pinmux_map name field to
> name those states, and allowing dynamic transitioning between states,
> rather than adding a complete new API and namespace for these states.
I am not sure how this works, but with dynamic transitioning, will it
be possible to program the pinmux registers dynamically when a
driver/controller decides to idle for sometime and come back up again
(not a system wide suspend-resume cycle). There might be a need for
the driver to inform the pinmux subsystem of this case and allow the
pinmux subsystem to re-program pinmux registers as required.
Thanks,
Thomas.
>
> --
> nvpublic
>
>
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RE: [PATCH] ARM: SAMSUNG: Save/restore GPIO drive strength across suspend/resume
Thomas Abraham wrote at Monday, November 14, 2011 6:57 AM:
> On 12 November 2011 16:30, Linus Walleij wrote:
> > On Sat, Nov 12, 2011 at 6:01 AM, Inderpal Singh
> > wrote:
> >
> >> GPIO driver strength settings are not preserved across suspend/resume
> >> for s5pc100, s5pv210 and Exynos platforms which has been the cause of
> >> mmc/sd card read/write failures after resume. Fix this by saving and
> >> restoring the GPIO driver strength register settings across suspend/resume.
> >>
> >> Signed-off-by: Inderpal Singh
> >
> > On a related theme: I am thinking about how to support preserving
> > drive strength (etc) across suspend/resume and deepsleep in the
> > pincontrol subsystem.
> >
> > Currently I am playing with the idea to let pin groups have states,
> > as the different configurations seem to be 90% or so about very
> > specific sleep modes, so say:
> >
> > pinconf_set_group_state("mmcgroup", PINCONF_STATE_ACTIVE);
> > pinconf_set_group_state("mmcgroup", PINCONF_STATE_SUSPENDED);
> > pinconf_set_group_state("mmcgroup", PINCONF_STATE_SLEEP);
>
>
> The API name suggests that power state is set based on a pin group.
> For a driver, the following could be convenient as the driver transits
> through various power management states.
>
> struct pinmux pmx;
> pmx = pinmux_get(dev, "i2c0");
>
> [...]
>
> pinmux_set_state(pmx, PINCONF_STATE_SLEEP);
> [...]
> pinmux_set_state(pmx, PINCONF_STATE_ACTIVE);
That seems a more consistent driver-oriented API, yes.
I'd of course lean towards adding the pin config data into the mapping
table, and using the existing feature struct pinmux_map name field to
name those states, and allowing dynamic transitioning between states,
rather than adding a complete new API and namespace for these states.
--
nvpublic
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Re: [PATCH] ARM: SAMSUNG: Save/restore GPIO drive strength across suspend/resume
Hi Linus,
On 12 November 2011 16:30, Linus Walleij wrote:
> On Sat, Nov 12, 2011 at 6:01 AM, Inderpal Singh
> wrote:
>
>> GPIO driver strength settings are not preserved across suspend/resume
>> for s5pc100, s5pv210 and Exynos platforms which has been the cause of
>> mmc/sd card read/write failures after resume. Fix this by saving and
>> restoring the GPIO driver strength register settings across suspend/resume.
>>
>> Signed-off-by: Inderpal Singh
>
> On a related theme: I am thinking about how to support preserving
> drive strength (etc) across suspend/resume and deepsleep in the
> pincontrol subsystem.
>
> Currently I am playing with the idea to let pin groups have states,
> as the different configurations seem to be 90% or so about very
> specific sleep modes, so say:
>
> pinconf_set_group_state("mmcgroup", PINCONF_STATE_ACTIVE);
> pinconf_set_group_state("mmcgroup", PINCONF_STATE_SUSPENDED);
> pinconf_set_group_state("mmcgroup", PINCONF_STATE_SLEEP);
The API name suggests that power state is set based on a pin group.
For a driver, the following could be convenient as the driver transits
through various power management states.
struct pinmux pmx;
pmx = pinmux_get(dev, "i2c0");
[...]
pinmux_set_state(pmx, PINCONF_STATE_SLEEP);
[...]
pinmux_set_state(pmx, PINCONF_STATE_ACTIVE);
>
> This would then instruct each pin controller driver to configure
> each pin apropriately for the given state, and that cross-references
> to a table keeping track of the preset per-pin for each state.
>
> My intuitive idea is that letting the core keep track of the state of
> every pin and letting pin groups harness the settings for a group
> of pins is the proper approach to the problem.
>
> Do you think something like this will work for the S5P:s?
Adding the responsibility of managing/configuring registers for
different power states to a pin group does seem suitable for Exynos.
Along with the pin list, a implementation of a pin group could include
a callback to manage the registers for a particular pin state. Such a
callback could be reused for all the pin groups as required.
Thanks,
Thomas.
>
> Yours,
> Linus Walleij
>
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Re: [PATCH] ARM: SAMSUNG: Save/restore GPIO drive strength across suspend/resume
On Sat, Nov 12, 2011 at 6:01 AM, Inderpal Singh
wrote:
> GPIO driver strength settings are not preserved across suspend/resume
> for s5pc100, s5pv210 and Exynos platforms which has been the cause of
> mmc/sd card read/write failures after resume. Fix this by saving and
> restoring the GPIO driver strength register settings across suspend/resume.
>
> Signed-off-by: Inderpal Singh
On a related theme: I am thinking about how to support preserving
drive strength (etc) across suspend/resume and deepsleep in the
pincontrol subsystem.
Currently I am playing with the idea to let pin groups have states,
as the different configurations seem to be 90% or so about very
specific sleep modes, so say:
pinconf_set_group_state("mmcgroup", PINCONF_STATE_ACTIVE);
pinconf_set_group_state("mmcgroup", PINCONF_STATE_SUSPENDED);
pinconf_set_group_state("mmcgroup", PINCONF_STATE_SLEEP);
This would then instruct each pin controller driver to configure
each pin apropriately for the given state, and that cross-references
to a table keeping track of the preset per-pin for each state.
My intuitive idea is that letting the core keep track of the state of
every pin and letting pin groups harness the settings for a group
of pins is the proper approach to the problem.
Do you think something like this will work for the S5P:s?
Yours,
Linus Walleij
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