[PATCH v2] drm/i915/bxt: use NULL for GPIO connection ID

[Mika Kahola]

On Thu, 2017-08-17 at 14:06 +0300, Mika Kahola wrote:
> Tested with GLK + MIPI/DSI panel (AU Optronics B101UAN01)
Tested also with APL + MIPI/DSI setup.

> 
> Tested-by: Mika Kahola <mika.kahola at intel.com>
> 
> On Thu, 2017-08-17 at 13:55 +0300, Andy Shevchenko wrote:
> > 
> > The commit 213e08ad60ba
> > 	("drm/i915/bxt: add bxt dsi gpio element support")
> > enables GPIO support for Broxton based platforms.
> > 
> > While using that API we might get into troubles in the future,
> > because
> > we can't rely on label name in the driver since vendor firmware
> > might
> > provide any GPIO pin there, e.g. "reset", and even mark it in _DSD
> > (in
> > which case the request will fail).
> > 
> > To avoid inconsistency and potential issues we have two options:
> > a) generate GPIO ACPI mapping table and supply it via
> >    acpi_dev_add_driver_gpios(), or
> > b) just pass NULL as connection ID.
> > 
> > The b) approach is much simpler and would work since the driver
> > relies
> > on GPIO indices only. Moreover, the _CRS fallback mechanism, when
> > requesting GPIO, has been made stricter, and supplying non-NULL
> > connection ID when neither _DSD, nor GPIO ACPI mapping is present,
> > is
> > making request fail.
> > 
> > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=101921
> > Fixes: f10e4bf6632b ("gpio: acpi: Even more tighten up ACPI GPIO
> > lookups")
> > Cc: Mika Kahola <mika.kahola at intel.com>
> > Cc: Jani Nikula <jani.nikula at intel.com>
> > Signed-off-by: Andy Shevchenko <andriy.shevchenko at linux.intel.com>
> > ---
> > v2:
> >  - adjust commit message for proper time tenses
> >  - add Fixes: and Bugzilla: tags
> >  drivers/gpu/drm/i915/intel_dsi_vbt.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/intel_dsi_vbt.c
> > b/drivers/gpu/drm/i915/intel_dsi_vbt.c
> > index 7158c7ce9c09..91c07b0c8db9 100644
> > --- a/drivers/gpu/drm/i915/intel_dsi_vbt.c
> > +++ b/drivers/gpu/drm/i915/intel_dsi_vbt.c
> > @@ -306,7 +306,7 @@ static void bxt_exec_gpio(struct
> > drm_i915_private
> > *dev_priv,
> >  
> >  	if (!gpio_desc) {
> >  		gpio_desc = devm_gpiod_get_index(dev_priv-
> > >drm.dev,
> > -						 "panel",
> > gpio_index,
> > +						 NULL, gpio_index,
> >  						 value ?
> > GPIOD_OUT_LOW :
> >  						 GPIOD_OUT_HIGH);
> >  
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-- 
Mika Kahola - Intel OTC