Re: [PATCH v2 2/2] drm: dw-hdmi: gate audio clock from the I2S enablement callbacks

[Archit Taneja]

On 04/19/2017 10:21 AM, Archit Taneja wrote:
> On 04/14/2017 02:01 PM, Romain Perier wrote:
> > Currently, the audio sampler clock is enabled from dw_hdmi_setup() at
> > step E. and is kept enabled for later use. This clock should be enabled
> > and disabled along with the actual audio stream and not always on (that
> > is bad for PM). Futhermore, as described by the datasheet, the I2S
>
> s/Futhermore/Furthermore
>
> > variant need to gate/ungate the clock when the stream is
>
> s/need/needs
>
> > enabled/disabled.
> >
> > This commit adds a parameter to hdmi_audio_enable_clk() that controls
> > when the audio sample clock must be enabled or disabled. Then, it adds
> > the call to this function from dw_hdmi_i2s_audio_enable() and
> > dw_hdmi_i2s_audio_disable().
> >
> > Signed-off-by: Romain Perier <romain.perier@xxxxxxxxxxxxx>
> > ---
> >  drivers/gpu/drm/bridge/synopsys/dw-hdmi.c | 20 ++++++++++++++------
> >  1 file changed, 14 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> > index 5b328c0..a6da634 100644
> > --- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> > +++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> > @@ -544,6 +544,12 @@ void dw_hdmi_set_sample_rate(struct dw_hdmi *hdmi, unsigned int rate)
> >  }
> >  EXPORT_SYMBOL_GPL(dw_hdmi_set_sample_rate);
> >
> > +static void hdmi_enable_audio_clk(struct dw_hdmi *hdmi, bool enable)
> > +{
> > +    hdmi_modb(hdmi, enable ? 0 : HDMI_MC_CLKDIS_AUDCLK_DISABLE,
> > +          HDMI_MC_CLKDIS_AUDCLK_DISABLE, HDMI_MC_CLKDIS);
> > +}
> > +
> >  void dw_hdmi_ahb_audio_enable(struct dw_hdmi *hdmi)
> >  {
> >      hdmi_set_cts_n(hdmi, hdmi->audio_cts, hdmi->audio_n);
> > @@ -557,6 +563,12 @@ void dw_hdmi_ahb_audio_disable(struct dw_hdmi *hdmi)
> >  void dw_hdmi_i2s_audio_enable(struct dw_hdmi *hdmi)
> >  {
> >      hdmi_set_cts_n(hdmi, hdmi->audio_cts, hdmi->audio_n);
> > +    hdmi_enable_audio_clk(hdmi, true);
> > +}
> > +
> > +void dw_hdmi_i2s_audio_disable(struct dw_hdmi *hdmi)
> > +{
> > +    hdmi_enable_audio_clk(hdmi, false);
> >  }
>
> This should be static too.
>
> If you're okay with the suggestions, I can fix these myself and push. Let
> me know if that's okay.

Took the liberty of going ahead with the fixes. Queued both patches to
drm-misc-next.

Thanks,
Archit

> Thanks,
> Archit
>
> >  void dw_hdmi_audio_enable(struct dw_hdmi *hdmi)
> > @@ -1592,11 +1604,6 @@ static void dw_hdmi_enable_video_path(struct dw_hdmi *hdmi)
> >                  HDMI_MC_FLOWCTRL);
> >  }
> >
> > -static void hdmi_enable_audio_clk(struct dw_hdmi *hdmi)
> > -{
> > -    hdmi_modb(hdmi, 0, HDMI_MC_CLKDIS_AUDCLK_DISABLE, HDMI_MC_CLKDIS);
> > -}
> > -
> >  /* Workaround to clear the overflow condition */
> >  static void dw_hdmi_clear_overflow(struct dw_hdmi *hdmi)
> >  {
> > @@ -1710,7 +1717,7 @@ static int dw_hdmi_setup(struct dw_hdmi *hdmi, struct drm_display_mode *mode)
> >
> >          /* HDMI Initialization Step E - Configure audio */
> >          hdmi_clk_regenerator_update_pixel_clock(hdmi);
> > -        hdmi_enable_audio_clk(hdmi);
> > +        hdmi_enable_audio_clk(hdmi, true);
> >      }
> >
> >      /* not for DVI mode */
> > @@ -2438,6 +2445,7 @@ __dw_hdmi_probe(struct platform_device *pdev,
> >          audio.write    = hdmi_writeb;
> >          audio.read    = hdmi_readb;
> >          hdmi->enable_audio = dw_hdmi_i2s_audio_enable;
> > +        hdmi->disable_audio = dw_hdmi_i2s_audio_disable;
> >
> >          pdevinfo.name = "dw-hdmi-i2s-audio";
> >          pdevinfo.data = &audio;

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