On Fri, 2016-11-04 at 17:48 +0200, Jani Nikula wrote:
> On Wed, 26 Oct 2016, Dhinakaran Pandiyan <dhinakaran.pandiyan@xxxxxxxxx> wrote:
> > Enabling DP audio stall fix is necessary to play audio over DP HBR2. So,
> > let's set this bit right before enabling the audio codec. Playing audio
> > without setting this bit results in pipe FIFO underruns.
> >
> > This workaround is applicable only for audio sample rates up to 96kHz. For
> > frequencies above 96kHz, this is insufficient and cdclk should be increased
> > to at least 432 MHz, just like BDW. Since, the audio driver does not
> > support sample rates > 48 kHz, we are safe with this fix for now.
>
> Do we still need this patch now that these two have been pushed?
>
> b30ce9e0552a drm/i915/dp: BDW cdclk fix for DP audio
> 9c7540241885 drm/i915/dp: Extend BDW DP audio workaround to GEN9 platforms
>
> BR,
> Jani.
>
>
>
No, we are good afaik. This patch would have helped us to make use of a
lower cdclk (337.5 MHz), with constraints on audio bit rate. Operating
at 432 MHz, like we do now, rules out the need for this patch.
-DK
> >
> > v2: Inlined the code change within hsw_audio_codec_enable() (Jani)
> > Fixed the port clock typo
> > Added TODO comment
> > Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@xxxxxxxxx>
> > ---
> > drivers/gpu/drm/i915/i915_reg.h | 5 +++++
> > drivers/gpu/drm/i915/intel_audio.c | 30 +++++++++++++++++++++++++++++-
> > 2 files changed, 34 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> > index 00efaa1..76dac48 100644
> > --- a/drivers/gpu/drm/i915/i915_reg.h
> > +++ b/drivers/gpu/drm/i915/i915_reg.h
> > @@ -6236,6 +6236,11 @@ enum {
> > #define SLICE_ECO_CHICKEN0 _MMIO(0x7308)
> > #define PIXEL_MASK_CAMMING_DISABLE (1 << 14)
> >
> > +#define _CHICKEN_TRANS_A 0x420C0
> > +#define _CHICKEN_TRANS_B 0x420C4
> > +#define CHICKEN_TRANS(tran) _MMIO_TRANS(tran, _CHICKEN_TRANS_A, _CHICKEN_TRANS_B)
> > +#define SPARE_13 (1<<13)
> > +
> > /* WaCatErrorRejectionIssue */
> > #define GEN7_SQ_CHICKEN_MBCUNIT_CONFIG _MMIO(0x9030)
> > #define GEN7_SQ_CHICKEN_MBCUNIT_SQINTMOB (1<<11)
> > diff --git a/drivers/gpu/drm/i915/intel_audio.c b/drivers/gpu/drm/i915/intel_audio.c
> > index 7093cfb..894f11e 100644
> > --- a/drivers/gpu/drm/i915/intel_audio.c
> > +++ b/drivers/gpu/drm/i915/intel_audio.c
> > @@ -283,6 +283,8 @@ static void hsw_audio_codec_disable(struct intel_encoder *encoder)
> > {
> > struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
> > struct intel_crtc *intel_crtc = to_intel_crtc(encoder->base.crtc);
> > + struct intel_crtc_state *crtc_config = intel_crtc->config;
> > + enum transcoder cpu_transcoder = crtc_config->cpu_transcoder;
> > enum pipe pipe = intel_crtc->pipe;
> > uint32_t tmp;
> >
> > @@ -290,13 +292,21 @@ static void hsw_audio_codec_disable(struct intel_encoder *encoder)
> >
> > mutex_lock(&dev_priv->av_mutex);
> >
> > + /*Disable DP audio stall fix for HBR2*/
> > + if (IS_GEN9(dev_priv) && intel_crtc_has_dp_encoder(crtc_config) &&
> > + crtc_config->port_clock >= 540000) {
> > + tmp = I915_READ(CHICKEN_TRANS(cpu_transcoder));
> > + tmp &= ~SPARE_13;
> > + I915_WRITE(CHICKEN_TRANS(cpu_transcoder), tmp);
> > + }
> > +
> > /* Disable timestamps */
> > tmp = I915_READ(HSW_AUD_CFG(pipe));
> > tmp &= ~AUD_CONFIG_N_VALUE_INDEX;
> > tmp |= AUD_CONFIG_N_PROG_ENABLE;
> > tmp &= ~AUD_CONFIG_UPPER_N_MASK;
> > tmp &= ~AUD_CONFIG_LOWER_N_MASK;
> > - if (intel_crtc_has_dp_encoder(intel_crtc->config))
> > + if (intel_crtc_has_dp_encoder(crtc_config))
> > tmp |= AUD_CONFIG_N_VALUE_INDEX;
> > I915_WRITE(HSW_AUD_CFG(pipe), tmp);
> >
> > @@ -315,6 +325,8 @@ static void hsw_audio_codec_enable(struct drm_connector *connector,
> > {
> > struct drm_i915_private *dev_priv = to_i915(connector->dev);
> > struct intel_crtc *intel_crtc = to_intel_crtc(intel_encoder->base.crtc);
> > + struct intel_crtc_state *crtc_config = intel_crtc->config;
> > + enum transcoder cpu_transcoder = crtc_config->cpu_transcoder;
> > enum pipe pipe = intel_crtc->pipe;
> > enum port port = intel_encoder->port;
> > const uint8_t *eld = connector->eld;
> > @@ -326,6 +338,22 @@ static void hsw_audio_codec_enable(struct drm_connector *connector,
> >
> > mutex_lock(&dev_priv->av_mutex);
> >
> > + /* Enable DP audio stall fix for HBR2
> > + *
> > + * TODO: This workaround is applicable only for audio sample rates up
> > + * to 96kHz. For frequencies above 96kHz, this is insufficient and
> > + * cdclk should be increased to at least 432 MHz, just like BDW. Since,
> > + * the audio driver does not support sample rates > 48 kHz, we are safe
> > + * with this fix for now.
> > + */
> > +
> > + if (IS_GEN9(dev_priv) && intel_crtc_has_dp_encoder(crtc_config) &&
> > + crtc_config->port_clock >= 540000) {
> > + tmp = I915_READ(CHICKEN_TRANS(cpu_transcoder));
> > + tmp |= SPARE_13;
> > + I915_WRITE(CHICKEN_TRANS(cpu_transcoder), tmp);
> > + }
> > +
> > /* Enable audio presence detect, invalidate ELD */
> > tmp = I915_READ(HSW_AUD_PIN_ELD_CP_VLD);
> > tmp |= AUDIO_OUTPUT_ENABLE(pipe);
>
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