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SubjectRe: [PATCH 3/3] drm/bridge: sii902x: make audio mclk optional
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On 02.07.2019 17:47, Olivier Moysan wrote:
> The master clock on i2s bus is not mandatory,
> as sii902X internal PLL can be used instead.
> Make use of mclk optional.
>
> Fixes: ff5781634c41 ("drm/bridge: sii902x: Implement HDMI audio support")
>
> Signed-off-by: Olivier Moysan <olivier.moysan@st.com>
> ---
> drivers/gpu/drm/bridge/sii902x.c | 39 +++++++++++++++++++++++----------------
> 1 file changed, 23 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/sii902x.c b/drivers/gpu/drm/bridge/sii902x.c
> index 36acc256e67e..a08bd9fdc046 100644
> --- a/drivers/gpu/drm/bridge/sii902x.c
> +++ b/drivers/gpu/drm/bridge/sii902x.c
> @@ -562,19 +562,21 @@ static int sii902x_audio_hw_params(struct device *dev, void *data,
> }
> }
>
> - ret = clk_prepare_enable(sii902x->audio.mclk);
> - if (ret) {
> - dev_err(dev, "Enabling mclk failed: %d\n", ret);
> - return ret;
> - }
> + if (sii902x->audio.mclk) {
> + ret = clk_prepare_enable(sii902x->audio.mclk);
> + if (ret) {
> + dev_err(dev, "Enabling mclk failed: %d\n", ret);
> + return ret;
> + }
>
> - mclk_rate = clk_get_rate(sii902x->audio.mclk);
> + mclk_rate = clk_get_rate(sii902x->audio.mclk);
>
> - ret = sii902x_select_mclk_div(&i2s_config_reg, params->sample_rate,
> - mclk_rate);
> - if (mclk_rate != ret * params->sample_rate)
> - dev_dbg(dev, "Inaccurate reference clock (%ld/%d != %u)\n",
> - mclk_rate, ret, params->sample_rate);
> + ret = sii902x_select_mclk_div(&i2s_config_reg,
> + params->sample_rate, mclk_rate);
> + if (mclk_rate != ret * params->sample_rate)
> + dev_dbg(dev, "Inaccurate reference clock (%ld/%d != %u)\n",
> + mclk_rate, ret, params->sample_rate);
> + }
>
> mutex_lock(&sii902x->mutex);
>
> @@ -640,7 +642,8 @@ static int sii902x_audio_hw_params(struct device *dev, void *data,
> mutex_unlock(&sii902x->mutex);
>
> if (ret) {
> - clk_disable_unprepare(sii902x->audio.mclk);
> + if (sii902x->audio.mclk)
> + clk_disable_unprepare(sii902x->audio.mclk);


"if" clause is not necessary


> dev_err(dev, "%s: hdmi audio enable failed: %d\n", __func__,
> ret);
> }
> @@ -659,7 +662,8 @@ static void sii902x_audio_shutdown(struct device *dev, void *data)
>
> mutex_unlock(&sii902x->mutex);
>
> - clk_disable_unprepare(sii902x->audio.mclk);
> + if (sii902x->audio.mclk)

ditto

> + clk_disable_unprepare(sii902x->audio.mclk);
> }
>
> int sii902x_audio_digital_mute(struct device *dev, void *data, bool enable)
> @@ -752,9 +756,12 @@ static int sii902x_audio_codec_init(struct sii902x *sii902x,
>
> sii902x->audio.mclk = devm_clk_get(dev, "mclk");
> if (IS_ERR(sii902x->audio.mclk)) {
> - dev_err(dev, "%s: No clock (audio mclk) found: %ld\n",
> - __func__, PTR_ERR(sii902x->audio.mclk));
> - return 0;
> + if (PTR_ERR(sii902x->audio.mclk) != -ENOENT) {
> + dev_err(dev, "%s: No clock (audio mclk) found: %ld\n",
> + __func__, PTR_ERR(sii902x->audio.mclk));
> + return PTR_ERR(sii902x->audio.mclk);
> + }
> + sii902x->audio.mclk = NULL;


devm_clk_get_optional should be used here.

Summarizing, clk framework supports NULL clocks so you can adjust code
to benefit from it: no need to checks "if (sii902x->audio.mclk)". The
only place you should care is near clk_get_rate, for null clock it will
return 0, so you should react appropriately.

With that changed:

Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>

 --
Regards
Andrzej


> }
>
> sii902x->audio.pdev = platform_device_register_data(


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