Re: [PATCH 02/12] drm/i915: Read PSR caps/intermediate freqs/etc. only once on eDP

Ville Syrjälä
2016-07-28T17:45:03Z

On Thu, Jul 28, 2016 at 06:30:47PM +0100, Chris Wilson wrote:
> On Thu, Jul 28, 2016 at 05:50:38PM +0300, ville.syrjala@linux.intel.com wrote:
> > From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> >
> > Currently we re-read a bunch of static eDP panel caps from the DPCD
> > over and over again. Let's do it only once to save some time and effort.
> >
> > Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
>
> > static bool
> > intel_dp_get_dpcd(struct intel_dp *intel_dp)
> > {
> > - struct intel_digital_port *dig_port = dp_to_dig_port(intel_dp);
> > - struct drm_device *dev = dig_port->base.base.dev;
> > - struct drm_i915_private *dev_priv = to_i915(dev);
> > + bool init_edp_dpcd = is_edp(intel_dp) &&
> > + intel_dp->dpcd[DP_DPCD_REV] == 0;
> >
> > if (drm_dp_dpcd_read(&intel_dp->aux, 0x000, intel_dp->dpcd,
> > sizeof(intel_dp->dpcd)) < 0)
>
> > + if (init_edp_dpcd)
> > + intel_edp_get_dpcd(intel_dp);
>
> I have to admit it took me a few passes to realise how this achieves
> init once.
>
> bool intel_dp_dpcd_is_unset(intel_dp)
> {
> return intel_dp->dpcd[DP_DPCD_REV] == 0;
> }
>
> Not really sure how else to make it clear to the causal reader that test
> is only true on the first call.

First I thought I'd just call the eDP specific function from the
connector init, but then I realized it needs to happen after reading the
regular DPCD stuff, but before printing out the rates/etc. So in the end
I just left it where it was and added the bool. I suppose it should be
possible to refactor the thing somehow to make it less confusing.

I guess I can give it one more try, and if I should fail, I'll suck in
your intel_dp_dpcd_is_unset() at least...

--
Ville Syrjälä
Intel OTC