On Tue, 06 Jun 2017, Imre Deak <imre.deak@xxxxxxxxx> wrote: > On Tue, Jun 06, 2017 at 05:58:43PM +0300, Bloomfield, Jon wrote: >> > -----Original Message----- >> > From: Intel-gfx [mailto:intel-gfx-bounces@xxxxxxxxxxxxxxxxxxxxx] On Behalf >> > Of Imre Deak >> > Sent: Tuesday, June 6, 2017 5:34 AM >> > To: Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx> >> > Cc: intel-gfx@xxxxxxxxxxxxxxxxxxxxx; Mustaffa, Mustamin B >> > <mustamin.b.mustaffa@xxxxxxxxx> >> > Subject: Re: [PATCH] drm/i915/bxt: Enable VBT based BL control >> > for DP >> > >> > On Tue, Jun 06, 2017 at 12:24:30PM +0300, Jani Nikula wrote: >> > > On Tue, 06 Jun 2017, Mustamin B Mustaffa >> > <mustamin.b.mustaffa@xxxxxxxxx> wrote: >> > > > [...] >> > > > diff --git a/drivers/gpu/drm/i915/intel_dp.c >> > b/drivers/gpu/drm/i915/intel_dp.c >> > > > index d1670b8..124f58b 100644 >> > > > --- a/drivers/gpu/drm/i915/intel_dp.c >> > > > +++ b/drivers/gpu/drm/i915/intel_dp.c >> > > > @@ -591,13 +591,8 @@ bxt_power_sequencer_idx(struct intel_dp >> > *intel_dp) >> > > > /* We should never land here with regular DP ports */ >> > > > WARN_ON(!is_edp(intel_dp)); >> > > > >> > > > - /* >> > > > - * TODO: BXT has 2 PPS instances. The correct port->PPS instance >> > > > - * mapping needs to be retrieved from VBT, for now just hard-code >> > to >> > > > - * use instance #0 always. >> > > > - */ >> > > > if (!intel_dp->pps_reset) >> > > > - return 0; >> > > > + return dev_priv->vbt.backlight.controller; >> > > >> > > So the existing code around here looks a bit convoluted, not least >> > > because now pretty much all PPS access first does >> > > >> > > - intel_pps_get_registers(), which calls >> > > - bxt_power_sequencer_idx(), which calls >> > > - intel_dp_init_panel_power_sequencer_registers(), which calls >> > > - intel_pps_get_registers()... >> > > >> > > With your change, for controller == 1 and pps_reset == true, the first >> > > time the registers are needed, we'll initialize the correct controller 1 >> > > registers, but controller 0 registers are returned. From there on, we'll >> > > keep returning controller 1 registers until pps_reset is set to true >> > > again. >> > > >> > > Cc: Imre as author of commits 78597996370c ("drm/i915/bxt: Fix PPS lost >> > > state after suspend breaking eDP link training") and 8e8232d51878 >> > > ("drm/i915: Deduplicate PPS register retrieval") which I think create >> > > the loop. >> > >> > A loop would be prevented by the pps->reset check, but agree the code >> > isn't nice, I guess I overlooked this when I wrote it. To make things >> > clearer we could factor out a helper from >> > intel_dp_init_panel_power_sequencer_registers() that takes pps_registers >> > and call this helper from bxt_power_sequencer_idx(). >> > >> > So how about something like the following: >> >> Just checking what the intention is here because your proposed change >> ommits the VBT fix... Are you going to post these changes as a new >> baseline for Mustaffa's patch ? Or are you asking Mustaffa to fold >> these changes into his patch ? Hoping it's the former :-) > > The change is just to make the code clearer, unrelated to the VBT fix, > so it should be a separate patch. I don't mind doing this as a follow-up > to Mustaffa's patchset. What his patch here would need is just to return > the correct index from bxt_power_sequencer_idx() in all cases. I think we might need to backport Mustaffa's patch to stable so we need to do that first as a standalone change. After it has been fixed according to Imre's and my feedback. Oh, and I'd still like someone(tm) to check if the PPS-PWM mapping is fixed 1:1, or can we cross connect them? I just involved Imre here because the existing code is, I think, unnecessarily hard to follow. BR, Jani. -- Jani Nikula, Intel Open Source Technology Center _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
