On 10/02/22 11:30 pm, Bartosz Golaszewski wrote:
On Thu, Feb 10, 2022 at 5:36 PM Gabriel Krisman Bertazi
<krisman@xxxxxxxxxxxxx> wrote:
Shreeya Patel <shreeya.patel@xxxxxxxxxxxxx> writes:
We are racing the registering of .to_irq when probing the
i2c driver. This results in random failure of touchscreen
devices.
Following errors could be seen in dmesg logs when gc->to_irq is NULL
[2.101857] i2c_hid i2c-FTS3528:00: HID over i2c has not been provided an Int IRQ
[2.101953] i2c_hid: probe of i2c-FTS3528:00 failed with error -22
To avoid this situation, defer probing until to_irq is registered.
This issue has been reported many times in past and people have been
using workarounds like changing the pinctrl_amd to built-in instead
of loading it as a module or by adding a softdep for pinctrl_amd into
the config file.
BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=209413
Reviewed-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
Reviewed-by: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>
Reported-by: kernel test robot <lkp@xxxxxxxxx>
Signed-off-by: Shreeya Patel <shreeya.patel@xxxxxxxxxxxxx>
Hi guys,
This seems to not have reached the Linus tree on 5.17. If I'm not
mistaken, it also hasn't reached linux-next as of today. Is there
anything I'm missing here?
This is required to prevent spurious probe crashes of devices like this
FocalTech touchscreen, FT3528, when using pinctrl-amd. We've been
carrying it downstream for quite a while.
Thanks,
--
Gabriel Krisman Bertazi
Hi Gabriel!
My email address changed in September, that's why I didn't see the
email you sent in November to my old one.
gpiod_to_irq() can be used in context other than driver probing, I'm
worried existing users would not know how to handle it. Also: how come
you can get the GPIO descriptor from the provider but its interrupts
are not yet set up?
Hi Bartosz,
We would be only changing the error code here for gpio driver race
condition.
Anything affected by this patch would have already been broken and might
be returning
-ENXIO. There is a theoretical chance that a driver exists which uses
gpiod_to_irq outside of
probe and affected by race condition. The more instructions between
gpiod_get and gpiod_to_irq
the smaller the chance of hitting the race condition though. Also
anything hitting the race condition
is broken right now and there hasn't been any issues reported so far. In
any case that system is not
fixed by this patch, it is still a good idea to apply this patch since
the proper fix is a lot more
invasive and probably might not be suitable for stable backporting. This
minimal patch does
not make things worse.
I have sent a v5 for this patch with better commit message.
Thanks,
Shreeya Patel
Bart
