Re: [PATCH v4 1/2] drm/i915/dp: Enable DP audio stall fix for gen9 platforms

From: Jani Nikula <jani.nikula@intel.com>
To: "Peter Frühberger" <fritsch@kodi.tv>,
	"Pandiyan, Dhinakaran" <dhinakaran.pandiyan@intel.com>
Cc: "intel-gfx@lists.freedesktop.org" <intel-gfx@lists.freedesktop.org>
Subject: Re: [PATCH v4 1/2] drm/i915/dp: Enable DP audio stall fix for gen9 platforms
Date: Wed, 04 Jan 2017 11:34:53 +0200	[thread overview]
Message-ID: <87r34jgoci.fsf@intel.com> (raw)
In-Reply-To: <CAFu8+fkf7tkHf4uQbhpjbdLR59YYagG8meS9eAL4=Lcn8_hdfA@mail.gmail.com>

On Wed, 04 Jan 2017, Peter Frühberger <fritsch@kodi.tv> wrote:
> Hi
>
> On Sun, Nov 6, 2016 at 1:23 AM, Pandiyan, Dhinakaran <
> dhinakaran.pandiyan@intel.com> wrote:
>
>> On Sat, 2016-11-05 at 21:40 +0200, Jani Nikula wrote:
>> > On Fri, 04 Nov 2016, "Pandiyan, Dhinakaran" <
>> dhinakaran.pandiyan@intel.com> wrote:
>> > > On Fri, 2016-11-04 at 17:48 +0200, Jani Nikula wrote:
>> > >> On Wed, 26 Oct 2016, Dhinakaran Pandiyan <
>> dhinakaran.pandiyan@intel.com> 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.
>> >
>> > Hmm, what about 5.4 Gbps link with 1 or 2 lanes?
>> >
>> > BR,
>> > Jani.
>> >
>>
>> Good point, I think it will depend on the audio sampling rate. But, I
>> have to figure out a way to play high sampling rate audio (> 96 KHz) and
>> test 5.4 Gbps with 1 or 2 lanes.
>>
>> The other option is to play safe and apply this patch with even lesser
>> restrictions, say link rate >= 2.7 Gbps.
>>
>>
>> -DK
>>
>
> as we are currently talking about high samplerates in this context. I
> wanted to post a perhaps related issue. On my Apollo Lake (J4205) I have
> two outputs. One DVI and one HDMI 2.0 via internal DP. Via DVI the
> following works without issues, via DP it fails. As the original commit
> mentions HBR, I think there is still something missing. We submit TrueHD,
> DTS-HD via 192 khz and 16 bit format while setting AES0=2
>
> You can easily reproduce with (you obviously need a DTS-HD, TrueHD capable
> AVR attached to your HDMI 2.0 (DP) out):

Just to clarify, is the DP -> HDMI2.0 converter internal to the machine?
LSPCON related messages in the dmesg with drm.debug=14? Do you have a DP
or an HDMI physical connector in the chassis?

BR,
Jani.

>
> #TrueHD
> aplay -D 'hdmi:CARD=PCH,DEV=0,AES0=2' -c8 -fs16_le -r192000
> testi.truehd.anssi1.ff.60s.spdif
> #DTS-HD
> aplay -D 'hdmi:CARD=PCH,DEV=0,AES0=2' -c8 -fs16_le -r192000
> testi.dtshd.anssi1.ma-71-24.spdif
> Samples:
> http://www.avenard.org/files/media/mediatest/audiotest/HDAUDIO/Passthrough/
>
> For the old HDMI 1.x chips it was fixed via:
> https://bugs.freedesktop.org/show_bug.cgi?id=49055
>
> Is this also planned for DP within that patch series?
>
> Best regards
> Peter
>
>>
>> > >
>> > > -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@intel.com>
>> > >> > ---
>> > >> >  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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>> Intel-gfx@lists.freedesktop.org
>> https://lists.freedesktop.org/mailman/listinfo/intel-gfx
>>

-- 
Jani Nikula, Intel Open Source Technology Center
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