Re: [PATCH] Revert "gpio: use new gpio_set_config() helper in more places"

[Andrew Jeffery]

On Wed, 27 Mar 2019, at 19:11, Bartosz Golaszewski wrote:
> wt., 26 mar 2019 o 19:06 Bartosz Golaszewski
> <bgolaszewski@xxxxxxxxxxxx> napisaÅ(a):
> >
> > wt., 26 mar 2019 o 05:50 Andrew Jeffery <andrew@xxxxxxxx> napisaÅ(a):
> > >
> > > gpio-aspeed implements support for PIN_CONFIG_INPUT_DEBOUNCE. As of
> > > v5.1-rc1 we're seeing the following when booting a Romulus BMC kernel:
> > >
> > > > [   21.373137] ------------[ cut here ]------------
> > > > [   21.374545] WARNING: CPU: 0 PID: 1 at drivers/gpio/gpio-aspeed.c:834 unregister_allocated_timer+0x38/0x94
> > > > [   21.376181] No timer allocated to offset 74
> > > > [   21.377672] CPU: 0 PID: 1 Comm: swapper Not tainted 5.1.0-rc1-dirty #6
> > > > [   21.378800] Hardware name: Generic DT based system
> > > > [   21.379965] Backtrace:
> > > > [   21.381024] [<80107d44>] (dump_backtrace) from [<80107f78>] (show_stack+0x20/0x24)
> > > > [   21.382713]  r7:8038b720 r6:00000009 r5:00000000 r4:87897c64
> > > > [   21.383815] [<80107f58>] (show_stack) from [<80656398>] (dump_stack+0x20/0x28)
> > > > [   21.385042] [<80656378>] (dump_stack) from [<80115f1c>] (__warn.part.3+0xb4/0xdc)
> > > > [   21.386253] [<80115e68>] (__warn.part.3) from [<80115fb0>] (warn_slowpath_fmt+0x6c/0x90)
> > > > [   21.387471]  r6:00000342 r5:807f8758 r4:80a07008
> > > > [   21.388278] [<80115f48>] (warn_slowpath_fmt) from [<8038b720>] (unregister_allocated_timer+0x38/0x94)
> > > > [   21.389809]  r3:0000004a r2:807f8774
> > > > [   21.390526]  r7:00000000 r6:0000000a r5:60000153 r4:0000004a
> > > > [   21.391601] [<8038b6e8>] (unregister_allocated_timer) from [<8038baac>] (aspeed_gpio_set_config+0x330/0x48c)
> > > > [   21.393248] [<8038b77c>] (aspeed_gpio_set_config) from [<803840b0>] (gpiod_set_debounce+0xe8/0x114)
> > > > [   21.394745]  r10:82ee2248 r9:00000000 r8:87b63a00 r7:00001388 r6:87947320 r5:80729310
> > > > [   21.396030]  r4:879f64a0
> > > > [   21.396499] [<80383fc8>] (gpiod_set_debounce) from [<804b4350>] (gpio_keys_probe+0x69c/0x8e0)
> > > > [   21.397715]  r7:845d94b8 r6:00000001 r5:00000000 r4:87b63a1c
> > > > [   21.398618] [<804b3cb4>] (gpio_keys_probe) from [<8040eeec>] (platform_dev_probe+0x44/0x80)
> > > > [   21.399834]  r10:00000003 r9:80a3a8b0 r8:00000000 r7:00000000 r6:80a7f9dc r5:80a3a8b0
> > > > [   21.401163]  r4:8796bc10
> > > > [   21.401634] [<8040eea8>] (platform_drv_probe) from [<8040d0d4>] (really_probe+0x208/0x3dc)
> > > > [   21.402786]  r5:80a7f8d0 r4:8796bc10
> > > > [   21.403547] [<8040cecc>] (really_probe) from [<8040d7a4>] (driver_probe_device+0x130/0x170)
> > > > [   21.404744]  r10:0000007b r9:8093683c r8:00000000 r7:80a07008 r6:80a3a8b0 r5:8796bc10
> > > > [   21.405854]  r4:80a3a8b0
> > > > [   21.406324] [<8040d674>] (driver_probe_device) from [<8040da8c>] (device_driver_attach+0x68/0x70)
> > > > [   21.407568]  r9:8093683c r8:00000000 r7:80a07008 r6:80a3a8b0 r5:00000000 r4:8796bc10
> > > > [   21.408877] [<8040da24>] (device_driver_attach) from [<8040db14>] (__driver_attach+0x80/0x150)
> > > > [   21.410327]  r7:80a07008 r6:8796bc10 r5:00000001 r4:80a3a8b0
> > > > [   21.411294] [<8040da94>] (__driver_attach) from [<8040b20c>] (bus_for_each_dev+0x80/0xc4)
> > > > [   21.412641]  r7:80a07008 r6:8040da94 r5:80a3a8b0 r4:87966f30
> > > > [   21.413580] [<8040b18c>] (bus_for_each_dev) from [<8040dc0c>] (driver_attach+0x28/0x30)
> > > > [   21.414943]  r7:00000000 r6:87b411e0 r5:80a33fc8 r4:80a3a8b0
> > > > [   21.415927] [<8040dbe4>] (driver_attach) from [<8040bbf0>] (bus_add_driver+0x14c/0x200)
> > > > [   21.417289] [<8040baa4>] (bus_add_driver) from [<8040e2b4>] (driver_register+0x84/0x118)
> > > > [   21.418652]  r7:80a60ae0 r6:809226b8 r5:80a07008 r4:80a3a8b0
> > > > [   21.419652] [<8040e230>] (driver_register) from [<8040fc28>] (__platform_driver_register+0x3c/0x50)
> > > > [   21.421193]  r5:80a07008 r4:809525f8
> > > > [   21.421990] [<8040fbec>] (__platform_driver_register) from [<809226d8>] (gpio_keys_init+0x20/0x28)
> > > > [   21.423447] [<809226b8>] (gpio_keys_init) from [<8090128c>] (do_one_initcall+0x80/0x180)
> > > > [   21.424886] [<8090120c>] (do_one_initcall) from [<80901538>] (kernel_init_freeable+0x1ac/0x26c)
> > > > [   21.426354]  r8:80a60ae0 r7:80a60ae0 r6:8093685c r5:00000008 r4:809525f8
> > > > [   21.427579] [<8090138c>] (kernel_init_freeable) from [<8066d9a0>] (kernel_init+0x18/0x11c)
> > > > [   21.428819]  r10:00000000 r9:00000000 r8:00000000 r7:00000000 r6:00000000 r5:8066d988
> > > > [   21.429947]  r4:00000000
> > > > [   21.430415] [<8066d988>] (kernel_init) from [<801010e8>] (ret_from_fork+0x14/0x2c)
> > > > [   21.431666] Exception stack(0x87897fb0 to 0x87897ff8)
> > > > [   21.432877] 7fa0:                                     00000000 00000000 00000000 00000000
> > > > [   21.434446] 7fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
> > > > [   21.436052] 7fe0: 00000000 00000000 00000000 00000000 00000013 00000000
> > > > [   21.437308]  r5:8066d988 r4:00000000
> > > > [   21.438102] ---[ end trace d7d7ac3a80567d0e ]---
> > >
> > > We only hit unregister_allocated_timer() if the argument to
> > > aspeed_gpio_set_config() is 0, but we can't be calling through
> > > gpiod_set_debounce() from gpio_keys_probe() unless the gpio-keys button has a
> > > non-zero debounce interval.
> > >
> > > Commit 6581eaf0e890 ("gpio: use new gpio_set_config() helper in more places")
> > > spreads the use of gpio_set_config() to the debounce and transitory
> > > state configuration paths. The implementation of gpio_set_config() is:
> > >
> > > > static int gpio_set_config(struct gpio_chip *gc, unsigned offset,
> > > >                          enum pin_config_param mode)
> > > > {
> > > >       unsigned long config = { PIN_CONF_PACKED(mode, 0) };
> > > >
> > > >       return gc->set_config ? gc->set_config(gc, offset, config) : -ENOTSUPP;
> > > > }
> > >
> > > Here it packs its own config value with a fixed argument of 0; this is
> > > incorrect behaviour for implementing the debounce and transitory functions, and
> > > the debounce and transitory gpio_set_config() call-sites now have an undetected
> > > type mismatch as they both already pack their own config parameter (i.e. what
> > > gets passed is not an `enum pin_config_param`). Indeed this can be seen in the
> > > small diff for 6581eaf0e890:
> > >
> > > > diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> > > > index de595fa31a1a..1f239aac43df 100644
> > > > --- a/drivers/gpio/gpiolib.c
> > > > +++ b/drivers/gpio/gpiolib.c
> > > > @@ -2725,7 +2725,7 @@ int gpiod_set_debounce(struct gpio_desc *desc, unsigned debounce)
> > > >         }
> > > >
> > > >         config = pinconf_to_config_packed(PIN_CONFIG_INPUT_DEBOUNCE, debounce);
> > > > -       return chip->set_config(chip, gpio_chip_hwgpio(desc), config);
> > > > +       return gpio_set_config(chip, gpio_chip_hwgpio(desc), config);
> > > >  }
> > > >  EXPORT_SYMBOL_GPL(gpiod_set_debounce);
> > > >
> > > > @@ -2762,7 +2762,7 @@ int gpiod_set_transitory(struct gpio_desc *desc, bool transitory)
> > > >         packed = pinconf_to_config_packed(PIN_CONFIG_PERSIST_STATE,
> > > >                                           !transitory);
> > > >         gpio = gpio_chip_hwgpio(desc);
> > > > -       rc = chip->set_config(chip, gpio, packed);
> > > > +       rc = gpio_set_config(chip, gpio, packed);
> > > >         if (rc == -ENOTSUPP) {
> > > >                 dev_dbg(&desc->gdev->dev, "Persistence not supported for GPIO %d\n",
> > > >                                 gpio);
> > >
> > > Revert commit 6581eaf0e890 ("gpio: use new gpio_set_config() helper in
> > > more places") to restore correct behaviour for gpiod_set_debounce() and
> > > gpiod_set_transitory().
> > >
> > > Cc: Thomas Petazzoni <thomas.petazzoni@xxxxxxxxxxx>
> > > Signed-off-by: Andrew Jeffery <andrew@xxxxxxxx>
> > > ---
> > >  drivers/gpio/gpiolib.c | 4 ++--
> > >  1 file changed, 2 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> > > index 144af0733581..0495bf1d480a 100644
> > > --- a/drivers/gpio/gpiolib.c
> > > +++ b/drivers/gpio/gpiolib.c
> > > @@ -2776,7 +2776,7 @@ int gpiod_set_debounce(struct gpio_desc *desc, unsigned debounce)
> > >         }
> > >
> > >         config = pinconf_to_config_packed(PIN_CONFIG_INPUT_DEBOUNCE, debounce);
> > > -       return gpio_set_config(chip, gpio_chip_hwgpio(desc), config);
> > > +       return chip->set_config(chip, gpio_chip_hwgpio(desc), config);
> > >  }
> > >  EXPORT_SYMBOL_GPL(gpiod_set_debounce);
> > >
> > > @@ -2813,7 +2813,7 @@ int gpiod_set_transitory(struct gpio_desc *desc, bool transitory)
> > >         packed = pinconf_to_config_packed(PIN_CONFIG_PERSIST_STATE,
> > >                                           !transitory);
> > >         gpio = gpio_chip_hwgpio(desc);
> > > -       rc = gpio_set_config(chip, gpio, packed);
> > > +       rc = chip->set_config(chip, gpio, packed);
> > >         if (rc == -ENOTSUPP) {
> > >                 dev_dbg(&desc->gdev->dev, "Persistence not supported for GPIO %d\n",
> > >                                 gpio);
> > > --
> > > 2.19.1
> > >
> >
> > Thanks for the detailed explanation of the problem. Can we check for
> > special cases in gpiod_set_config() and possibly pass the config
> > unchanged to the underlying driver in case of debounce and transitory
> > options?
> >
> > Bart
> 
> After giving it a second thought and seeing that Thomas is ok with
> reverting it, I applied the patch for fixes.

Ok, thanks. Didn't get around to addressing your reply today, so that's one less thing on the todo list :)

Andrew

> 
> Bart
>