Re: [PATCH] drm/i915: Add DPI FIFO empty status check

[Daniel Vetter <daniel@ffwll.ch>]

On Wed, Dec 09, 2015 at 04:34:54PM +0200, Ville Syrjälä wrote:
> On Wed, Dec 09, 2015 at 05:05:52PM +0530, Deepak M wrote:
> > From: Gaurav K Singh <gaurav.k.singh@intel.com>
> > 
> > Before sending TURN ON packet,check the DPI
> > FIFO empty status.
> > 
> > v2: Change in commit message
> >     Checking for FIFO empty  only during TURN ON packet.
> > v3: Adding a new function for DPI FIFO empty check
> > 
> > Signed-off-by: Gaurav K Singh <gaurav.k.singh@intel.com>
> > Signed-off-by: Deepak M <m.deepak@intel.com>
> > ---
> >  drivers/gpu/drm/i915/intel_dsi.c | 15 ++++++++++++++-
> >  1 file changed, 14 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/intel_dsi.c b/drivers/gpu/drm/i915/intel_dsi.c
> > index 170ae6f..eff982b 100644
> > --- a/drivers/gpu/drm/i915/intel_dsi.c
> > +++ b/drivers/gpu/drm/i915/intel_dsi.c
> > @@ -60,6 +60,17 @@ static void wait_for_dsi_fifo_empty(struct intel_dsi *intel_dsi, enum port port)
> >  		DRM_ERROR("DPI FIFOs are not empty\n");
> >  }
> >  
> > +static void wait_for_dpi_fifo_empty(struct intel_dsi *intel_dsi, enum port port)
> > +{
> > +	struct drm_encoder *encoder = &intel_dsi->base.base;
> > +	struct drm_device *dev = encoder->dev;
> > +	struct drm_i915_private *dev_priv = dev->dev_private;
> 
> Passing in intel_dsi just to dig out the dev_priv again seems a bit
> pointless. Could just pass dev_priv directly. But I guess it matches the
> already existing functions. 
> 
> BTW for future reference, we would rather see to_i915(<whatever>)
> instead of <whatever>->dev_private.

Yeah I think fixing up the above would be good. We're pretty close to
being able to embed our device structure.
-Daniel

> 
> Anyway, the patch seems to do what it says. I can't really judge
> whether it's the right thing to do though.
> 
> Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> 
> > +
> > +	if (wait_for((I915_READ(MIPI_GEN_FIFO_STAT(port)) & DPI_FIFO_EMPTY)
> > +					== DPI_FIFO_EMPTY, 50))
> > +		DRM_ERROR("Timeout waiting for DPI FIFO empty\n");
> > +}
> > +
> >  static void write_data(struct drm_i915_private *dev_priv, u32 reg,
> >  		       const u8 *data, u32 len)
> >  {
> > @@ -443,8 +454,10 @@ static void intel_dsi_enable(struct intel_encoder *encoder)
> >  			I915_WRITE(MIPI_MAX_RETURN_PKT_SIZE(port), 8 * 4);
> >  	} else {
> >  		msleep(20); /* XXX */
> > -		for_each_dsi_port(port, intel_dsi->ports)
> > +		for_each_dsi_port(port, intel_dsi->ports) {
> > +			wait_for_dpi_fifo_empty(intel_dsi, port);
> >  			dpi_send_cmd(intel_dsi, TURN_ON, false, port);
> > +		}
> >  		msleep(100);
> >  
> >  		drm_panel_enable(intel_dsi->panel);
> > -- 
> > 1.9.1
> > 
> > _______________________________________________
> > Intel-gfx mailing list
> > Intel-gfx@lists.freedesktop.org
> > http://lists.freedesktop.org/mailman/listinfo/intel-gfx
> 
> -- 
> Ville Syrjälä
> Intel OTC
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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