Re: [PATCH 3/4] drm/vc4: use new helper to get ACR values

[Maxime Ripard]

On Sun, Mar 09, 2025 at 10:13:58AM +0200, Dmitry Baryshkov wrote:
> From: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
> 
> Use drm_hdmi_acr_get_n_cts() helper instead of calculating N and CTS
> values in the VC4 driver.
> 
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
> ---
>  drivers/gpu/drm/vc4/vc4_hdmi.c | 10 +++-------
>  drivers/gpu/drm/vc4/vc4_hdmi.h |  7 +++++++
>  2 files changed, 10 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
> index 37238a12baa58a06a5d6f40d1ab64abc7fac60d7..f24bcc2f3a2ac39aaea061b809940978341472f4 100644
> --- a/drivers/gpu/drm/vc4/vc4_hdmi.c
> +++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
> @@ -1637,6 +1637,7 @@ static void vc4_hdmi_encoder_atomic_mode_set(struct drm_encoder *encoder,
>  		      &crtc_state->adjusted_mode);
>  	vc4_hdmi->output_bpc = conn_state->hdmi.output_bpc;
>  	vc4_hdmi->output_format = conn_state->hdmi.output_format;
> +	vc4_hdmi->tmds_char_rate = conn_state->hdmi.tmds_char_rate;
>  	mutex_unlock(&vc4_hdmi->mutex);
>  }
>  
> @@ -1829,17 +1830,12 @@ static void vc4_hdmi_audio_set_mai_clock(struct vc4_hdmi *vc4_hdmi,
>  
>  static void vc4_hdmi_set_n_cts(struct vc4_hdmi *vc4_hdmi, unsigned int samplerate)
>  {
> -	const struct drm_display_mode *mode = &vc4_hdmi->saved_adjusted_mode;
> -	u32 n, cts;
> -	u64 tmp;
> +	unsigned int n, cts;
>  
>  	lockdep_assert_held(&vc4_hdmi->mutex);
>  	lockdep_assert_held(&vc4_hdmi->hw_lock);
>  
> -	n = 128 * samplerate / 1000;
> -	tmp = (u64)(mode->clock * 1000) * n;
> -	do_div(tmp, 128 * samplerate);
> -	cts = tmp;
> +	drm_hdmi_acr_get_n_cts(vc4_hdmi->tmds_char_rate, samplerate, &n, &cts);
>  
>  	HDMI_WRITE(HDMI_CRP_CFG,
>  		   VC4_HDMI_CRP_CFG_EXTERNAL_CTS_EN |
> diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.h b/drivers/gpu/drm/vc4/vc4_hdmi.h
> index e3d989ca302b72533c374dfa3fd0d5bd7fe64a82..0a775dbfe99d45521f3d0a2016555aefa81d7934 100644
> --- a/drivers/gpu/drm/vc4/vc4_hdmi.h
> +++ b/drivers/gpu/drm/vc4/vc4_hdmi.h
> @@ -211,6 +211,13 @@ struct vc4_hdmi {
>  	 * KMS hooks. Protected by @mutex.
>  	 */
>  	enum hdmi_colorspace output_format;
> +
> +	/**
> +	 * @tmds_char_rate: Copy of
> +	 * @drm_connector_state.hdmi.tmds_char_rate for use outside of
> +	 * KMS hooks. Protected by @mutex.
> +	 */
> +	unsigned long long tmds_char_rate;
>  };

This should be in drm_connector_hdmi if it's useful

Maxime

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