On Wed, Jan 24, 2018 at 09:25:06AM +0000, Jani Nikula wrote: > On Tue, 23 Jan 2018, Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx> wrote: > > On Tue, Jan 23, 2018 at 05:40:50PM +0000, Rodrigo Vivi wrote: > >> Let's ignore VBT request if the pin is clearly wrong. > >> > >> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=104139 > >> Cc: Kai Heng Feng <kai.heng.feng@xxxxxxxxxxxxx> > >> Signed-off-by: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx> > > > > Reviewed-by: Radhakrishna Sripada <radhakrishna.sripada@xxxxxxxxx> > > (f2f) > > thanks > > > > merged to dinq. > > A bit too fast IMO. The bug report doesn't include the vbt dump which > you should *always* look at before making workarounds for vbt. my apologies. My biggest mistake was taking so long to reply to the bug and taking so long to post the patch here. :( I looked to the VBT now and it is really just this ddc pin for this particular port wrong. Or should I look to something else? What other kind of useful information would that bring to us normally? > > Also, see below. > > >> --- > >> drivers/gpu/drm/i915/intel_bios.c | 11 ++++++++--- > >> 1 file changed, 8 insertions(+), 3 deletions(-) > >> > >> diff --git a/drivers/gpu/drm/i915/intel_bios.c b/drivers/gpu/drm/i915/intel_bios.c > >> index b0668202dc7e..95f0b310d656 100644 > >> --- a/drivers/gpu/drm/i915/intel_bios.c > >> +++ b/drivers/gpu/drm/i915/intel_bios.c > >> @@ -1115,9 +1115,14 @@ static const u8 cnp_ddc_pin_map[] = { > >> > >> static u8 map_ddc_pin(struct drm_i915_private *dev_priv, u8 vbt_pin) > >> { > >> - if (HAS_PCH_CNP(dev_priv) && > >> - vbt_pin > 0 && vbt_pin < ARRAY_SIZE(cnp_ddc_pin_map)) > >> - return cnp_ddc_pin_map[vbt_pin]; > >> + if (HAS_PCH_CNP(dev_priv)) { > >> + if (vbt_pin > 0 && vbt_pin < ARRAY_SIZE(cnp_ddc_pin_map)) > >> + return cnp_ddc_pin_map[vbt_pin]; > >> + if (vbt_pin > GMBUS_PIN_4_CNP) { > >> + DRM_DEBUG_KMS("Ignoring alternate pin: VBT claims DDC pin %d, which is not valid for this platform\n", vbt_pin); > >> + return 0; > >> + } > > The original code was wrong in the sense that it would only do the > mapping if the provided vbt_pin was within bounds for CNP, and would > return the unmapped vbt_pin otherwise. Instead, I think you should > directly return 0 for out of bounds vbt_pin. > > This change here is effectively the same, but more confusing. As if > there's a case where the vbt_pin can be both out of bounds, within CNP > pin limits, and should be returned unmapped. That can't happen, so > please make the code reflect that. Yes. That's a great idea. Thanks for the suggestion. Honestly, at first I assumed our behavior was something like this so I couldn't believe we had the issue even with the original mapping there. But when I did the last fix I avoided changing the original behavior and messed things up. Sorry. Thanks, Rodrigo. > > BR, > Jani. > > > >> + } > >> > >> return vbt_pin; > >> } > >> -- > >> 2.13.6 > >> > > _______________________________________________ > > Intel-gfx mailing list > > Intel-gfx@xxxxxxxxxxxxxxxxxxxxx > > https://lists.freedesktop.org/mailman/listinfo/intel-gfx > > -- > Jani Nikula, Intel Open Source Technology Center _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
