Re: [PATCH 07/22] drm/i915/audio: Protect singleton register with a lock

[Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx>]

On Tue, 11 Oct 2022, Ville Syrjala <ville.syrjala@xxxxxxxxxxxxxxx> wrote:
> From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
>
> On the "ilk" platforms AUD_CNTL_ST2 is a singleton. Protect
> it with the audio mutex in case we ever want to do parallel
> RMW access to it.
>
> Currently that should not happen since we only do audio
> enable/disable from full modesets, and those are fully
> serialized. But we probably want to think about toggling
> audio on/off from fastsets too.
>
> The hsw codepaths alreayd already have the same locking.
> g4x should not need it since it can only do audio to a
> single port at a time, which means it's actually broken
> in more ways than this atm.

"alreayd already"

Reviewed-by: Jani Nikula <jani.nikula@xxxxxxxxx>

>
> Cc: Chaitanya Kumar Borah <chaitanya.kumar.borah@xxxxxxxxx>
> Cc: Kai Vehmanen <kai.vehmanen@xxxxxxxxxxxxxxx>
> Cc: Takashi Iwai <tiwai@xxxxxxx>
> Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> ---
>  drivers/gpu/drm/i915/display/intel_audio.c | 7 +++++++
>  1 file changed, 7 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_audio.c b/drivers/gpu/drm/i915/display/intel_audio.c
> index c6f0c8be82b2..9a286d70e281 100644
> --- a/drivers/gpu/drm/i915/display/intel_audio.c
> +++ b/drivers/gpu/drm/i915/display/intel_audio.c
> @@ -707,6 +707,8 @@ static void ilk_audio_codec_disable(struct intel_encoder *encoder,
>  
>  	ilk_audio_regs_init(i915, pipe, &regs);
>  
> +	mutex_lock(&i915->display.audio.mutex);
> +
>  	/* Disable timestamps */
>  	tmp = intel_de_read(i915, regs.aud_config);
>  	tmp &= ~AUD_CONFIG_N_VALUE_INDEX;
> @@ -721,6 +723,8 @@ static void ilk_audio_codec_disable(struct intel_encoder *encoder,
>  	tmp = intel_de_read(i915, regs.aud_cntrl_st2);
>  	tmp &= ~IBX_ELD_VALID(port);
>  	intel_de_write(i915, regs.aud_cntrl_st2, tmp);
> +
> +	mutex_unlock(&i915->display.audio.mutex);
>  }
>  
>  static void ilk_audio_codec_enable(struct intel_encoder *encoder,
> @@ -749,6 +753,7 @@ static void ilk_audio_codec_enable(struct intel_encoder *encoder,
>  
>  	ilk_audio_regs_init(i915, pipe, &regs);
>  
> +	mutex_lock(&i915->display.audio.mutex);
>  
>  	/* Invalidate ELD */
>  	tmp = intel_de_read(i915, regs.aud_cntrl_st2);
> @@ -781,6 +786,8 @@ static void ilk_audio_codec_enable(struct intel_encoder *encoder,
>  	else
>  		tmp |= audio_config_hdmi_pixel_clock(crtc_state);
>  	intel_de_write(i915, regs.aud_config, tmp);
> +
> +	mutex_unlock(&i915->display.audio.mutex);
>  }
>  
>  /**

-- 
Jani Nikula, Intel Open Source Graphics Center