Re: [PATCH 2/7] drm/i915: add DisplayPort amp unmute for LPE audio mode

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Tue, Jan 31, 2017 at 10:36:44PM +0100, Takashi Iwai wrote:
> From: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
> 
> Enable unmute/mute amp notification. This doesn't seem to affect
> HDMI support so this is done unconditionally.
> 
> An earlier version of this patch set a chicken bit at address 0x62F38
> prior to the mute/unmute but this register doesn't seem to do anything
> so this phase was removed.
> 
> Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
> Signed-off-by: Takashi Iwai <tiwai@suse.de>
> ---
>  drivers/gpu/drm/i915/i915_reg.h        | 10 ++++++++++
>  drivers/gpu/drm/i915/intel_lpe_audio.c | 17 +++++++++++++++++
>  2 files changed, 27 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index a9ffc8df241b..8fcc80cb864b 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -2061,6 +2061,16 @@ enum skl_disp_power_wells {
>  #define I915_HDMI_LPE_AUDIO_BASE	(VLV_DISPLAY_BASE + 0x65000)
>  #define I915_HDMI_LPE_AUDIO_SIZE	0x1000
>  
> +/* DisplayPort Audio w/ LPE */
> +#define VLV_AUD_PORT_EN_B_DBG		(VLV_DISPLAY_BASE + 0x62F20)
> +#define VLV_AUD_PORT_EN_C_DBG		(VLV_DISPLAY_BASE + 0x62F30)
> +#define VLV_AUD_PORT_EN_D_DBG		(VLV_DISPLAY_BASE + 0x62F34)
> +#define VLV_AUD_PORT_EN_DBG(port)	_MMIO_PORT3((port) - PORT_B,	   \
> +						    VLV_AUD_PORT_EN_B_DBG, \
> +						    VLV_AUD_PORT_EN_C_DBG, \
> +						    VLV_AUD_PORT_EN_D_DBG)
> +#define VLV_AMP_MUTE		        (1 << 1)
> +
>  #define GEN6_BSD_RNCID			_MMIO(0x12198)
>  
>  #define GEN7_FF_THREAD_MODE		_MMIO(0x20a0)
> diff --git a/drivers/gpu/drm/i915/intel_lpe_audio.c b/drivers/gpu/drm/i915/intel_lpe_audio.c
> index 245523e14418..f95624a46f27 100644
> --- a/drivers/gpu/drm/i915/intel_lpe_audio.c
> +++ b/drivers/gpu/drm/i915/intel_lpe_audio.c
> @@ -337,15 +337,25 @@ void intel_lpe_audio_notify(struct drm_i915_private *dev_priv,
>  {
>  	unsigned long irq_flags;
>  	struct intel_hdmi_lpe_audio_pdata *pdata = NULL;
> +	u32 audio_enable;
> +	i915_reg_t mmio;
>  
>  	if (!HAS_LPE_AUDIO(dev_priv))
>  		return;
>  
> +	if (port == PORT_A) {
> +		DRM_ERROR("PORT_A is not valid for HDMI/DP usages\n");
> +		return;
> +	}

Port A doesn't exists on these platforms at all. So this is
just dead code.

> +
>  	pdata = dev_get_platdata(
>  		&(dev_priv->lpe_audio.platdev->dev));
>  
>  	spin_lock_irqsave(&pdata->lpe_audio_slock, irq_flags);
>  
> +	mmio = VLV_AUD_PORT_EN_DBG(port);

I'm not a fan of these temporary reg offset variables. Makes it hard to
figure out later which register is being frobbed, especially when the
variable name doesn't say what it actually is (like in this case). So
I'd like to see this killed off.

> +	audio_enable = I915_READ(mmio);
> +
>  	if (eld != NULL) {
>  		memcpy(pdata->eld.eld_data, eld,
>  			HDMI_MAX_ELD_BYTES);
> @@ -357,11 +367,18 @@ void intel_lpe_audio_notify(struct drm_i915_private *dev_priv,
>  			pdata->tmds_clock_speed = tmds_clk_speed;
>  		if (link_rate)
>  			pdata->link_rate = link_rate;
> +
> +		/* Unmute the amp for both DP and HDMI */
> +		I915_WRITE(mmio, audio_enable & ~VLV_AMP_MUTE);
> +
>  	} else {
>  		memset(pdata->eld.eld_data, 0,
>  			HDMI_MAX_ELD_BYTES);
>  		pdata->hdmi_connected = false;
>  		pdata->dp_output = false;
> +
> +		/* Mute the amp for both DP and HDMI */
> +		I915_WRITE(mmio, audio_enable | VLV_AMP_MUTE);
>  	}
>  
>  	if (pdata->notify_audio_lpe)
> -- 
> 2.11.0

-- 
Ville Syrjälä
Intel OTC
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