Re: [PATCH] drm: bridge/dw_hdmi: add audio sample channel status setting

[Cheng-yi Chiang <cychiang@chromium.org>]

Hi,

On Tue, Sep 3, 2019 at 5:53 PM Neil Armstrong <narmstrong@baylibre.com> wrote:
>
> Hi,
>
> On 03/09/2019 07:51, Cheng-Yi Chiang wrote:
> > From: Yakir Yang <ykk@rock-chips.com>
> >
> > When transmitting IEC60985 linear PCM audio, we configure the
> > Audio Sample Channel Status information of all the channel
> > status bits in the IEC60958 frame.
> > Refer to 60958-3 page 10 for frequency, original frequency, and
> > wordlength setting.
> >
> > This fix the issue that audio does not come out on some monitors
> > (e.g. LG 22CV241)
> >
> > Signed-off-by: Yakir Yang <ykk@rock-chips.com>
> > Signed-off-by: Cheng-Yi Chiang <cychiang@chromium.org>
> > ---
> >  drivers/gpu/drm/bridge/synopsys/dw-hdmi.c | 59 +++++++++++++++++++++++
> >  drivers/gpu/drm/bridge/synopsys/dw-hdmi.h | 20 ++++++++
> >  2 files changed, 79 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> > index bd65d0479683..34d46e25d610 100644
> > --- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> > +++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> > @@ -582,6 +582,63 @@ static unsigned int hdmi_compute_n(unsigned int freq, unsigned long pixel_clk)
> >       return n;
> >  }
> >
> > +static void hdmi_set_schnl(struct dw_hdmi *hdmi)
> > +{
> > +     u8 aud_schnl_samplerate;
> > +     u8 aud_schnl_8;
> > +
> > +     /* These registers are on RK3288 using version 2.0a. */
> > +     if (hdmi->version != 0x200a)
> > +             return;
>
> Are these limited to the 2.0a version *in* RK3288, or 2.0a version on all
> SoCs ?
>

In the original patch by Yakir,

https://lore.kernel.org/patchwork/patch/539653/   (sorry, I should
have added this link in the "after the cut" note)

The fix is limited to version 2.0.
Since I am only testing on RK3288 with 2.0a, I change the check to 2.0a only.
I can not test 2.0a version on other SoCs.
The databook I have at hand is 2.0a (not specific to RK3288) so I
think all 2.0a should have this register.

As for other version like version 1.3 on iMX6, there is no such
register, as stated by Russell

http://lkml.iu.edu/hypermail/linux/kernel/1501.3/06268.html.

So at least we should check the version.
Maybe we can set the criteria as version 2.0 or above to make it a safe patch ?
If there is the same need on other SoC with version < 2.0, it can be
added later.
Presumably, there will be databook of that version to help confirming
this setting.

Thanks!
> > +
> > +     switch (hdmi->sample_rate) {
> > +     case 32000:
> > +             aud_schnl_samplerate = HDMI_FC_AUDSCHNLS7_SMPRATE_32K;
> > +             break;
> > +     case 44100:
> > +             aud_schnl_samplerate = HDMI_FC_AUDSCHNLS7_SMPRATE_44K1;
> > +             break;
> > +     case 48000:
> > +             aud_schnl_samplerate = HDMI_FC_AUDSCHNLS7_SMPRATE_48K;
> > +             break;
> > +     case 88200:
> > +             aud_schnl_samplerate = HDMI_FC_AUDSCHNLS7_SMPRATE_88K2;
> > +             break;
> > +     case 96000:
> > +             aud_schnl_samplerate = HDMI_FC_AUDSCHNLS7_SMPRATE_96K;
> > +             break;
> > +     case 176400:
> > +             aud_schnl_samplerate = HDMI_FC_AUDSCHNLS7_SMPRATE_176K4;
> > +             break;
> > +     case 192000:
> > +             aud_schnl_samplerate = HDMI_FC_AUDSCHNLS7_SMPRATE_192K;
> > +             break;
> > +     case 768000:
> > +             aud_schnl_samplerate = HDMI_FC_AUDSCHNLS7_SMPRATE_768K;
> > +             break;
> > +     default:
> > +             dev_warn(hdmi->dev, "Unsupported audio sample rate (%u)\n",
> > +                      hdmi->sample_rate);
> > +             return;
> > +     }
> > +
> > +     /* set channel status register */
> > +     hdmi_modb(hdmi, aud_schnl_samplerate, HDMI_FC_AUDSCHNLS7_SMPRATE_MASK,
> > +               HDMI_FC_AUDSCHNLS7);
> > +
> > +     /*
> > +      * Set original frequency to be the same as frequency.
> > +      * Use one-complement value as stated in IEC60958-3 page 13.
> > +      */
> > +     aud_schnl_8 = (~aud_schnl_samplerate) <<
> > +                     HDMI_FC_AUDSCHNLS8_ORIGSAMPFREQ_OFFSET;
> > +
> > +     /* This means word length is 16 bit. Refer to IEC60958-3 page 12. */
> > +     aud_schnl_8 |= 2 << HDMI_FC_AUDSCHNLS8_WORDLEGNTH_OFFSET;
> > +
> > +     hdmi_writeb(hdmi, aud_schnl_8, HDMI_FC_AUDSCHNLS8);
> > +}
> > +
> >  static void hdmi_set_clk_regenerator(struct dw_hdmi *hdmi,
> >       unsigned long pixel_clk, unsigned int sample_rate)
> >  {
> > @@ -620,6 +677,8 @@ static void hdmi_set_clk_regenerator(struct dw_hdmi *hdmi,
> >       hdmi->audio_cts = cts;
> >       hdmi_set_cts_n(hdmi, cts, hdmi->audio_enable ? n : 0);
> >       spin_unlock_irq(&hdmi->audio_lock);
> > +
> > +     hdmi_set_schnl(hdmi);
> >  }
> >
> >  static void hdmi_init_clk_regenerator(struct dw_hdmi *hdmi)
> > diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.h b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.h
> > index 6988f12d89d9..619ebc1c8354 100644
> > --- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.h
> > +++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.h
> > @@ -158,6 +158,17 @@
> >  #define HDMI_FC_SPDDEVICEINF                    0x1062
> >  #define HDMI_FC_AUDSCONF                        0x1063
> >  #define HDMI_FC_AUDSSTAT                        0x1064
> > +#define HDMI_FC_AUDSV                           0x1065
> > +#define HDMI_FC_AUDSU                           0x1066
> > +#define HDMI_FC_AUDSCHNLS0                      0x1067
> > +#define HDMI_FC_AUDSCHNLS1                      0x1068
> > +#define HDMI_FC_AUDSCHNLS2                      0x1069
> > +#define HDMI_FC_AUDSCHNLS3                      0x106a
> > +#define HDMI_FC_AUDSCHNLS4                      0x106b
> > +#define HDMI_FC_AUDSCHNLS5                      0x106c
> > +#define HDMI_FC_AUDSCHNLS6                      0x106d
> > +#define HDMI_FC_AUDSCHNLS7                      0x106e
> > +#define HDMI_FC_AUDSCHNLS8                      0x106f
> >  #define HDMI_FC_DATACH0FILL                     0x1070
> >  #define HDMI_FC_DATACH1FILL                     0x1071
> >  #define HDMI_FC_DATACH2FILL                     0x1072
> > @@ -706,6 +717,15 @@ enum {
> >  /* HDMI_FC_AUDSCHNLS7 field values */
> >       HDMI_FC_AUDSCHNLS7_ACCURACY_OFFSET = 4,
> >       HDMI_FC_AUDSCHNLS7_ACCURACY_MASK = 0x30,
> > +     HDMI_FC_AUDSCHNLS7_SMPRATE_MASK = 0x0f,
> > +     HDMI_FC_AUDSCHNLS7_SMPRATE_192K = 0xe,
> > +     HDMI_FC_AUDSCHNLS7_SMPRATE_176K4 = 0xc,
> > +     HDMI_FC_AUDSCHNLS7_SMPRATE_96K = 0xa,
> > +     HDMI_FC_AUDSCHNLS7_SMPRATE_768K = 0x9,
> > +     HDMI_FC_AUDSCHNLS7_SMPRATE_88K2 = 0x8,
> > +     HDMI_FC_AUDSCHNLS7_SMPRATE_32K = 0x3,
> > +     HDMI_FC_AUDSCHNLS7_SMPRATE_48K = 0x2,
> > +     HDMI_FC_AUDSCHNLS7_SMPRATE_44K1 = 0x0,
> >
> >  /* HDMI_FC_AUDSCHNLS8 field values */
> >       HDMI_FC_AUDSCHNLS8_ORIGSAMPFREQ_MASK = 0xf0,
> >
>