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SubjectRe: [PATCH v2 2/2] drm: dw-hdmi: gate audio clock from the I2S enablement callbacks
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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@collabora.com>
>> ---
>> 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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a Linux Foundation Collaborative Project

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