On Wed, 10 Apr 2024, Uma Shankar <uma.shankar@xxxxxxxxx> 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) hsw_audio_codec_disable/enable get called on hsw and display ver >= 8, but a lot of those platforms have the bit reserved MBZ. I didn't go through all the platforms in bspec, but enough to notice this needs some platform check. BR, Jani. > > Signed-off-by: Uma Shankar <uma.shankar@xxxxxxxxx> > --- > drivers/gpu/drm/i915/display/intel_audio.c | 12 ++++++++++++ > drivers/gpu/drm/i915/display/intel_audio_regs.h | 3 +++ > 2 files changed, 15 insertions(+) > > diff --git a/drivers/gpu/drm/i915/display/intel_audio.c b/drivers/gpu/drm/i915/display/intel_audio.c > index 07e0c73204f3..a8e3e515aaa0 100644 > --- a/drivers/gpu/drm/i915/display/intel_audio.c > +++ b/drivers/gpu/drm/i915/display/intel_audio.c > @@ -512,6 +512,12 @@ 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 > + */ > + intel_de_rmw(i915, AUD_CHICKENBIT_REG3, CHICKEN3_SPARE18, 0); > + > mutex_unlock(&i915->display.audio.mutex); > } > > @@ -637,6 +643,12 @@ 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 > + */ > + 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__ */ -- Jani Nikula, Intel
