Hi Michal, On Wed, 31 Aug 2022 at 11:44, Simon Glass <s...@chromium.org> wrote: > > Hi Michal, > > On Wed, 31 Aug 2022 at 01:39, Michal Suchánek <msucha...@suse.de> wrote: > > > > Hello, > > > > On Tue, Aug 30, 2022 at 09:15:12PM -0600, Simon Glass wrote: > > > Hi Michal, > > > > > > On Tue, 30 Aug 2022 at 10:48, Michal Suchánek <msucha...@suse.de> wrote: > > > > > > > > On Tue, Aug 30, 2022 at 09:56:52AM -0600, Simon Glass wrote: > > > > > Hi Michal, > > > > > > > > > > On Tue, 30 Aug 2022 at 04:23, Michal Suchánek <msucha...@suse.de> > > > > > wrote: > > > > > > > > > > > > On Sat, Aug 27, 2022 at 07:52:27PM -0600, Simon Glass wrote: > > > > > > > Hi Michal, > > > > > > > > > > > > > > On Fri, 19 Aug 2022 at 14:23, Michal Suchanek <msucha...@suse.de> > > > > > > > wrote: > > > > > > > > > > > > > > > > When probing a device fails NULL pointer is returned, and other > > > > > > > > devices > > > > > > > > cannot be iterated. Skip to next device on error instead. > > > > > > > > > > > > > > > > Fixes: 6494d708bf ("dm: Add base driver model support") > > > > > > > > > > > > > > I think you should drop this as you are doing a change of > > > > > > > behaviour, > > > > > > > not fixing a bug! > > > > > > > > > > > > You can hardly fix a bug without a change in behavior. > > > > > > > > > > > > These functions are used for iterating devices, and are not > > > > > > iterating > > > > > > devices. That's clearly a bug. > > > > > > > > > > If it were clear I would have changed this long ago. The new way you > > > > > have this function ignores errors, so they cannot be reported. > > > > > > > > > > We should almost always report errors, which is why I think your > > > > > methods should be named differently. > > > > > > > > > > > > > > > > > > > Signed-off-by: Michal Suchanek <msucha...@suse.de> > > > > > > > > --- > > > > > > > > v2: - Fix up tests > > > > > > > > v3: - Fix up API doc > > > > > > > > - Correctly forward error from uclass_get > > > > > > > > - Do not return an error when last device fails to probe > > > > > > > > - Drop redundant initialization > > > > > > > > - Wrap at 80 columns > > > > > > > > --- > > > > > > > > drivers/core/uclass.c | 32 ++++++++++++++++++++++++-------- > > > > > > > > include/dm/uclass.h | 13 ++++++++----- > > > > > > > > test/dm/test-fdt.c | 20 ++++++++++++++++---- > > > > > > > > 3 files changed, 48 insertions(+), 17 deletions(-) > > > > > > > > > > > > > > Unfortunately this still fails one test. Try 'make qcheck' to see > > > > > > > it - > > > > > > > it is ethernet. > > > > > > > > > > > > I will look at that. > > > > > > > > > > > > > I actually think you should create new functions for this feature, > > > > > > > e.g.uclass_first_device_ok(), since it makes it impossible to see > > > > > > > what > > > > > > > when wrong with a device in the middle. > > > > > > > > > > > > > > I have long had all this in my mind. One idea for a future change > > > > > > > is > > > > > > > to return the error, but set dev, so that the caller knows there > > > > > > > is a > > > > > > > device, which failed. When we are at the end, dev is set to NULL. > > > > > > > > > > > > We already have uclass_first_device_check() and > > > > > > uclass_next_device_check() to iterate all devices, including broken > > > > > > ones, and getting the errors as well. > > > > > > > > > > > > That's for the case you want all the details, and these are for the > > > > > > case > > > > > > you just want to get devices and don't care about the details. > > > > > > > > > > > > That's AFAICT as much as this iteration interface can provide, and > > > > > > we > > > > > > have both cases covered. > > > > > > > > > > I see three cases: > > > > > - want to see the next device, returning the error if it cannot be > > > > > probed - uclass_first_device() > > > > > > > > And the point of this is what exactly? > > > > > > Please can you adjust your tone, It seems too aggressive for this > > > mailing list. Thank you. > > > > > > > > > > > The device order in the uclass is not well defined - at any time a new > > > > device which will become the first can be added, fail probe, and block > > > > what was assumed a loop iterating the uclass from returning any devices > > > > at all. That's exactly what happened with the new sysreset. > > > > > > The order only changes if the device is unbound and rebound. Otherwise > > > the order set by the device tree is used. > > > > So the order is defined by device tree. That does not make it > > well-defined from the point of view of any kind of code. > > > > The point of device tree is that it can be replaced with another device > > tree describing another board and the code should still work. Otherwise > > we would not need device trees, and could keep using board files. > > We do use the raw ordering in test code, but in general we use the > sequence number (from DT ordering or aliases) to provide the official > ordering (the uclass...seq() calls). > > > > > > > What is exactly the point of returning the error and not the pointer to > > > > the next device? > > > > > > Partly, we have existing code which uses the interface, checking 'dev' > > > to see if the device is valid. I would be happy to change that, so > > > that the device is always returned. In fact I think it would be > > > better. But it does need a bit of work with coccinelle, etc. > > > > I suppose changing the return type to void would catch the users that do > > something with the return value but it would still need building all > > the code. > > > > And it does not work for users of uclass_first_device_err which is > > basically useless after this change but pretty much all users use the > > return value. > > > > > > The only point of these simplified iterators is that the caller can > > > > check only one value (device pointer) and then not check the error > > > > because they don't care. If they do cate uclass_first_device_check() > > > > provides all the details available. > > > > > > Yes I think we can have just two sets of iterators, but in that case > > > it should be: > > > > > > - want to see the next device, returning the error if it cannot be > > > probed, with dev updated to the next device in any case - new version > > > of uclass_first_device() - basically rename > > > uclass_first_device_check() to that > > > > About 2/3 of users of uclass_first_device don't use the return value at > > all in current code. Changing uclass_first_device to > > uclass_first_device_check is counterproductive. The current > > documentation basically implies the new behavior, and there are a lot of > > examples in the core code that use uclass_first_device in a for loop > > without assigning the return value at all. > > > > Also renaming uclass_first_device_check would break the 3 existing users > > of it. > > > > > - want to see next device which probes OK - your new function, perhaps > > > uclass_first_device_ok() ? > > > > I don't think any amount of renaming is going to solve the problem at > > hand: we have bazillion of users of uclass_first_device, and because it > > was not documented that it does not in fact iterate uclass devices there > > are users that use it for the purpose. There are also users that expect > > maningful return value which is basically bogus - they do get a return > > value of something, but not something specific. > > > > What can be done is adding the simple iterator under new name, convert > > the obvious existing users, and mark the old function deprecated in some > > way so that any code that uses it generates a warning. > > I'm OK with that. But let's rename uclass_first_device() to > uclass_old_first_device() or something like that.
Just wondered if you have had time to respin this? -next is open and I'd like to apply this soon so we have maximal testing time. Regards, Simon