Re: [PATCH v2] drm/i915/dsi: skip gpio element execution when not supported

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Thu, Feb 04, 2016 at 07:22:30PM +0200, Jani Nikula wrote:
> On Thu, 04 Feb 2016, Ville Syrjälä <ville.syrjala@linux.intel.com> wrote:
> > On Thu, Feb 04, 2016 at 07:10:42PM +0200, Jani Nikula wrote:
> >> On Thu, 04 Feb 2016, Ville Syrjälä <ville.syrjala@linux.intel.com> wrote:
> >> > On Thu, Feb 04, 2016 at 06:52:47PM +0200, Jani Nikula wrote:
> >> >> Skip v3 gpio element because the support is not there, and skip gpio
> >> >> element on non-vlv because the sideband code is vlv specific.
> >> >> 
> >> >> v2: the gpio stuff is currently only supported on vlv (Ville)
> >> >> 
> >> >> Cc: drm-intel-fixes@lists.freedesktop.org
> >> >> Fixes: 2a33d93486f2 ("drm/i915/bios: add support for MIPI sequence block v3")
> >> >> Signed-off-by: Jani Nikula <jani.nikula@intel.com>
> >> >> ---
> >> >>  drivers/gpu/drm/i915/intel_dsi_panel_vbt.c | 13 +++++++++++++
> >> >>  1 file changed, 13 insertions(+)
> >> >> 
> >> >> diff --git a/drivers/gpu/drm/i915/intel_dsi_panel_vbt.c b/drivers/gpu/drm/i915/intel_dsi_panel_vbt.c
> >> >> index f4d303ee538b..bcc083db7632 100644
> >> >> --- a/drivers/gpu/drm/i915/intel_dsi_panel_vbt.c
> >> >> +++ b/drivers/gpu/drm/i915/intel_dsi_panel_vbt.c
> >> >> @@ -205,6 +205,9 @@ static const u8 *mipi_exec_gpio(struct intel_dsi *intel_dsi, const u8 *data)
> >> >>  	struct drm_device *dev = intel_dsi->base.base.dev;
> >> >>  	struct drm_i915_private *dev_priv = dev->dev_private;
> >> >>  
> >> >> +	if (dev_priv->vbt.dsi.seq_version >= 3)
> >> >> +		data++;
> >> >> +
> >> >
> >> > So here we handle v3
> >> >
> >> >>  	gpio = *data++;
> >> >>  
> >> >>  	/* pull up/down */
> >> >> @@ -215,6 +218,16 @@ static const u8 *mipi_exec_gpio(struct intel_dsi *intel_dsi, const u8 *data)
> >> >>  		goto out;
> >> >>  	}
> >> >>  
> >> >> +	if (!IS_VALLEYVIEW(dev_priv)) {
> >> >> +		DRM_DEBUG_KMS("GPIO element not supported on this platform\n");
> >> >> +		goto out;
> >> >> +	}
> >> >> +
> >> >> +	if (dev_priv->vbt.dsi.seq_version >= 3) {
> >> >> +		DRM_DEBUG_KMS("GPIO element v3 not supported\n");
> >> >> +		goto out;
> >> >> +	}
> >> >
> >> > but here we say it's not supported. Is there more missing?
> >> 
> >> The whole point of doing it this way is to support *skipping* v3 in a
> >> graceful manner. If I bailed out at the top, I'd have to duplicate the
> >> knowledge about the length of the element.
> >
> > Hmm, right. But the question still stands; what more is missing for
> > actual v3 support?
> 
> That's the ugly patch #8...?

Ah, right it's the randomly (?) chosen gpio pin blocks split thing.

> 
> > From what I saw in the spec, the new byte is there just for Windows.
> > Which in itself is an utter fail on part of the spec. There's no good
> > reason why Windows and Linux should do things differently because that
> > will probably mean putting Linux on some random machine that came with
> > Windows won't work :(
> 
> There's no disagreement here. Ugly specs lead to ugly implementations.
> 
> BR,
> Jani.
> 
> 
> 
> -- 
> Jani Nikula, Intel Open Source Technology Center

-- 
Ville Syrjälä
Intel OTC
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