On Thu, Apr 11, 2024 at 03:36:37PM -0700, Matt Roper wrote: > On Wed, Apr 10, 2024 at 07:20:46PM +0530, Uma Shankar wrote: > > WA_14020863754: Corner case with Min Hblank Fix can cause > > audio hang > > > > Issue: Previously a fix was made to avoid issues with extremely > > small hblanks, called the "Min Hblank Fix". However, this can > > potentially cause an audio hang. > > > > Workaround : > > During "Audio Programming Sequence" Audio Enabling - > > When DP mode is enabled Set mmio offset 0x65F1C bit 18 = 1b, > > before step #1 "Enable audio Presence Detect" > > > > During "Audio Programming Sequence" Audio Disabling - > > When DP mode is enabled Clear mmio offset 0x65F1C bit 18 = 0b, > > after step #6 "Disable Audio PD (Presence Detect)" > > If not clearing PD bit, must also not clear 0x65F1C bit 18 (leave = 1b) > > > > v2: Update the platform checks (Jani Nikula) > > > > Signed-off-by: Uma Shankar <uma.shankar@xxxxxxxxx> > > --- > > drivers/gpu/drm/i915/display/intel_audio.c | 14 ++++++++++++++ > > drivers/gpu/drm/i915/display/intel_audio_regs.h | 3 +++ > > 2 files changed, 17 insertions(+) > > > > diff --git a/drivers/gpu/drm/i915/display/intel_audio.c b/drivers/gpu/drm/i915/display/intel_audio.c > > index 07e0c73204f3..61df5115c970 100644 > > --- a/drivers/gpu/drm/i915/display/intel_audio.c > > +++ b/drivers/gpu/drm/i915/display/intel_audio.c > > @@ -512,6 +512,13 @@ static void hsw_audio_codec_disable(struct intel_encoder *encoder, > > intel_de_rmw(i915, HSW_AUD_PIN_ELD_CP_VLD, > > AUDIO_OUTPUT_ENABLE(cpu_transcoder), 0); > > > > + /* > > + * WA_14020863754: Implement Audio Workaround > > + * Corner case with Min Hblank Fix can cause audio hang > > + */ > > + if (DISPLAY_VER(i915) >= 20) > > The workaround is currently listed as applying to both Xe2_LPD (20.00) > and Xe2_HPD (14.01). So we should match on those precise IP versions > for now. Future platforms and/or refreshes may or may not need this > workaround and we don't want to just assume the workaround will carry > forward forever, so the condition may get updated further as new > platforms/IP versions are added to the driver. Also, since this is a workaround that requires logic in multiple spots and already applies to multiple IP versions, it may be a good idea to separate out the condition into a helper function so that if/when new versions get added to the list in the future we can update a single place rather than tracking down multiple 'if' statements. Matt > > > Matt > > > + intel_de_rmw(i915, AUD_CHICKENBIT_REG3, CHICKEN3_SPARE18, 0); > > + > > mutex_unlock(&i915->display.audio.mutex); > > } > > > > @@ -637,6 +644,13 @@ static void hsw_audio_codec_enable(struct intel_encoder *encoder, > > if (intel_crtc_has_type(crtc_state, INTEL_OUTPUT_DP)) > > enable_audio_dsc_wa(encoder, crtc_state); > > > > + /* > > + * WA_14020863754: Implement Audio Workaround > > + * Corner case with Min Hblank Fix can cause audio hang > > + */ > > + if (DISPLAY_VER(i915) >= 20) > > + intel_de_rmw(i915, AUD_CHICKENBIT_REG3, 0, CHICKEN3_SPARE18); > > + > > /* Enable audio presence detect */ > > intel_de_rmw(i915, HSW_AUD_PIN_ELD_CP_VLD, > > 0, AUDIO_OUTPUT_ENABLE(cpu_transcoder)); > > diff --git a/drivers/gpu/drm/i915/display/intel_audio_regs.h b/drivers/gpu/drm/i915/display/intel_audio_regs.h > > index 616e7b1275c4..6f8d33299ecd 100644 > > --- a/drivers/gpu/drm/i915/display/intel_audio_regs.h > > +++ b/drivers/gpu/drm/i915/display/intel_audio_regs.h > > @@ -148,4 +148,7 @@ > > #define HBLANK_START_COUNT_96 4 > > #define HBLANK_START_COUNT_128 5 > > > > +#define AUD_CHICKENBIT_REG3 _MMIO(0x65F1C) > > +#define CHICKEN3_SPARE18 REG_BIT(18) > > + > > #endif /* __INTEL_AUDIO_REGS_H__ */ > > -- > > 2.42.0 > > > > -- > Matt Roper > Graphics Software Engineer > Linux GPU Platform Enablement > Intel Corporation -- Matt Roper Graphics Software Engineer Linux GPU Platform Enablement Intel Corporation
