[Intel-gfx] [PATCH 1/4] drm/i915: Avoid EBUSY retry on intel_dp_aux_ch.

[Vivi, Rodrigo]

On Wed, 2015-10-21 at 12:19 +0300, Ville Syrjälä wrote:
> On Wed, Oct 21, 2015 at 10:28:51AM -0700, Rodrigo Vivi wrote:
> > EBUSY retries are already in place at drm level.
> > We don't need to replicate the job here.
> > 
> > Signed-off-by: Rodrigo Vivi <rodrigo.vivi at intel.com>
> > ---
> >  drivers/gpu/drm/i915/intel_dp.c | 20 ++------------------
> >  1 file changed, 2 insertions(+), 18 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/intel_dp.c 
> > b/drivers/gpu/drm/i915/intel_dp.c
> > index 09bdd94..d054129 100644
> > --- a/drivers/gpu/drm/i915/intel_dp.c
> > +++ b/drivers/gpu/drm/i915/intel_dp.c
> > @@ -818,24 +818,8 @@ intel_dp_aux_ch(struct intel_dp *intel_dp,
> >  
> >  	intel_aux_display_runtime_get(dev_priv);
> >  
> > -	/* Try to wait for any previous AUX channel activity */
> > -	for (try = 0; try < 3; try++) {
> > -		status = I915_READ_NOTRACE(ch_ctl);
> > -		if ((status & DP_AUX_CH_CTL_SEND_BUSY) == 0)
> > -			break;
> > -		msleep(1);
> 
> The dp helper doesn't sleep at all between the retries, so dropping 
> the
> sleep from here may change the behaviour.

hm indeed... what about 
+ msleep(1);
+ ret = -EBUSY
+ goto out;
?
> 
> > -	}
> > -
> > -	if (try == 3) {
> > -		static u32 last_status = -1;
> > -		const u32 status = I915_READ(ch_ctl);
> > -
> > -		if (status != last_status) {
> > -			WARN(1, "dp_aux_ch not started status 
> > 0x%08x\n",
> > -			     status);
> > -			last_status = status;
> > -		}
> > -
> > +	status = I915_READ_NOTRACE(ch_ctl);
> > +	if ((status & DP_AUX_CH_CTL_SEND_BUSY) != 0) {
> >  		ret = -EBUSY;
> >  		goto out;
> >  	}
> > -- 
> > 2.4.3
> > 
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>