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

[Takashi Iwai]

On Tue, 31 Jan 2017 22:36:44 +0100,
Takashi Iwai wrote:
> 
> From: Pierre-Louis Bossart <pierre-louis.bossart at 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.

Sorry, this seems like a wrong result.  It worked yesterday, but when
I retested the latest code today, it didn't work any longer.
Then, after setting the chicken bit, it starts working again.

But now I can't make it broken again.  Turn off the monitor, turn off
the machine, DPMS off, suspend/resume...  All still works without
chicken bit set.

Also, the chicken bit of the register 0x62f38 couldn't be read back.
The register always returns zero when read.

So the chicken bit helps definitely something on a device here, but
it's still mystery how it works.

I'll send an additional patch to re-add the audio chicken bit stuff.


thanks,

Takashi

> 
> Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart at linux.intel.com>
> Signed-off-by: Takashi Iwai <tiwai at 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;
> +	}
> +
>  	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);
> +	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
>