Re: [PATCH] drm/i915: set proper N/CTS in modeset

[Jani Nikula <jani.nikula@linux.intel.com>]

On Fri, 11 Sep 2015, libin.yang@intel.com wrote:
> From: Libin Yang <libin.yang@intel.com>
>
> When modeset occurs and the TMDS frequency is set to some
> speical values, the N/CTS need to be set manually if audio
> is playing.
>
> Signed-off-by: Libin Yang <libin.yang@intel.com>
> ---
>  drivers/gpu/drm/i915/intel_audio.c | 56 ++++++++++++++++++++++++++++++++------
>  include/drm/i915_component.h       | 10 +++++++
>  2 files changed, 57 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_audio.c b/drivers/gpu/drm/i915/intel_audio.c
> index e3c32ce..a12bf57 100644
> --- a/drivers/gpu/drm/i915/intel_audio.c
> +++ b/drivers/gpu/drm/i915/intel_audio.c
> @@ -128,6 +128,20 @@ static int audio_config_get_n(const struct drm_display_mode *mode, int rate)
>  	return 0;
>  }
>  
> +static uint32_t audio_config_setup_n_reg(int n, uint32_t val)
> +{
> +	int n_low, n_up;
> +	uint32_t tmp = val;
> +
> +	n_low = n & 0xfff;
> +	n_up = (n >> 12) & 0xff;
> +	tmp &= ~(AUD_CONFIG_UPPER_N_MASK | AUD_CONFIG_LOWER_N_MASK);
> +	tmp |= ((n_up << AUD_CONFIG_UPPER_N_SHIFT) |
> +			(n_low << AUD_CONFIG_LOWER_N_SHIFT) |
> +			AUD_CONFIG_N_PROG_ENABLE);
> +	return tmp;
> +}
> +
>  /* check whether N/CTS/M need be set manually */
>  static bool audio_rate_need_prog(struct intel_crtc *crtc,
>  					struct drm_display_mode *mode)
> @@ -262,9 +276,14 @@ static void hsw_audio_codec_enable(struct drm_connector *connector,
>  	struct drm_i915_private *dev_priv = connector->dev->dev_private;
>  	struct intel_crtc *intel_crtc = to_intel_crtc(encoder->base.crtc);
>  	enum pipe pipe = intel_crtc->pipe;
> +	struct i915_audio_component *acomp = dev_priv->audio_component;
>  	const uint8_t *eld = connector->eld;
> +	struct intel_digital_port *intel_dig_port =
> +		enc_to_dig_port(&encoder->base);
> +	enum port port = intel_dig_port->port;
>  	uint32_t tmp;
>  	int len, i;
> +	int n, rate;
>  
>  	DRM_DEBUG_KMS("Enable audio codec on pipe %c, %u bytes ELD\n",
>  		      pipe_name(pipe), drm_eld_size(eld));
> @@ -302,12 +321,29 @@ static void hsw_audio_codec_enable(struct drm_connector *connector,
>  	/* Enable timestamps */
>  	tmp = I915_READ(HSW_AUD_CFG(pipe));
>  	tmp &= ~AUD_CONFIG_N_VALUE_INDEX;
> -	tmp &= ~AUD_CONFIG_N_PROG_ENABLE;
>  	tmp &= ~AUD_CONFIG_PIXEL_CLOCK_HDMI_MASK;
>  	if (intel_pipe_has_type(intel_crtc, INTEL_OUTPUT_DISPLAYPORT))
>  		tmp |= AUD_CONFIG_N_VALUE_INDEX;
>  	else
>  		tmp |= audio_config_hdmi_pixel_clock(mode);
> +
> +	tmp &= ~AUD_CONFIG_N_PROG_ENABLE;
> +	if (audio_rate_need_prog(intel_crtc, mode)) {
> +		if (!acomp)
> +			rate = 0;
> +		else if (port >= PORT_A && port <= PORT_E)
> +			rate = acomp->aud_sample_rate[port];
> +		else {
> +			DRM_ERROR("invalid port: %d\n", port);
> +			rate = 0;
> +		}
> +		n = audio_config_get_n(mode, rate);
> +		if (n != 0)
> +			tmp = audio_config_setup_n_reg(n, tmp);
> +		else
> +			DRM_DEBUG_KMS("no suitable N value is found\n");
> +	}
> +
>  	I915_WRITE(HSW_AUD_CFG(pipe), tmp);
>  
>  	mutex_unlock(&dev_priv->av_mutex);
> @@ -594,9 +630,10 @@ static int i915_audio_component_sync_audio_rate(struct device *dev,
>  	struct intel_digital_port *intel_dig_port;
>  	struct intel_crtc *crtc;
>  	struct drm_display_mode *mode;
> +	struct i915_audio_component *acomp = dev_priv->audio_component;
>  	enum pipe pipe = -1;
>  	u32 tmp;
> -	int n_low, n_up, n;
> +	int n;
>  
>  	/* HSW, BDW SKL need this fix */
>  	if (!IS_SKYLAKE(dev_priv) &&
> @@ -630,6 +667,9 @@ static int i915_audio_component_sync_audio_rate(struct device *dev,
>  				  pipe_name(pipe), port_name(port));
>  	mode = &crtc->config->base.adjusted_mode;
>  
> +	/* port must be valid now, otherwise the pipe will be invalid */
> +	acomp->aud_sample_rate[port] = rate;
> +
>  	/* 2. check whether to set the N/CTS/M manually or not */
>  	if (!audio_rate_need_prog(crtc, mode)) {
>  		tmp = I915_READ(HSW_AUD_CFG(pipe));
> @@ -649,15 +689,10 @@ static int i915_audio_component_sync_audio_rate(struct device *dev,
>  		mutex_unlock(&dev_priv->av_mutex);
>  		return 0;
>  	}
> -	n_low = n & 0xfff;
> -	n_up = (n >> 12) & 0xff;
>  
> -	/* 4. set the N/CTS/M */
> +	/* 3. set the N/CTS/M */
>  	tmp = I915_READ(HSW_AUD_CFG(pipe));
> -	tmp &= ~(AUD_CONFIG_UPPER_N_MASK | AUD_CONFIG_LOWER_N_MASK);
> -	tmp |= ((n_up << AUD_CONFIG_UPPER_N_SHIFT) |
> -			(n_low << AUD_CONFIG_LOWER_N_SHIFT) |
> -			AUD_CONFIG_N_PROG_ENABLE);
> +	tmp = audio_config_setup_n_reg(n, tmp);
>  	I915_WRITE(HSW_AUD_CFG(pipe), tmp);
>  
>  	mutex_unlock(&dev_priv->av_mutex);
> @@ -678,6 +713,7 @@ static int i915_audio_component_bind(struct device *i915_dev,
>  {
>  	struct i915_audio_component *acomp = data;
>  	struct drm_i915_private *dev_priv = dev_to_i915(i915_dev);
> +	int i;
>  
>  	if (WARN_ON(acomp->ops || acomp->dev))
>  		return -EEXIST;
> @@ -685,6 +721,8 @@ static int i915_audio_component_bind(struct device *i915_dev,
>  	drm_modeset_lock_all(dev_priv->dev);
>  	acomp->ops = &i915_audio_component_ops;
>  	acomp->dev = i915_dev;
> +	for (i = 0; i < I915_MAX_PORTS; i++)
> +		acomp->aud_sample_rate[i] = 0;
>  	dev_priv->audio_component = acomp;
>  	drm_modeset_unlock_all(dev_priv->dev);
>  
> diff --git a/include/drm/i915_component.h b/include/drm/i915_component.h
> index e6d35d7..89dc7d6 100644
> --- a/include/drm/i915_component.h
> +++ b/include/drm/i915_component.h
> @@ -24,8 +24,18 @@
>  #ifndef _I915_COMPONENT_H_
>  #define _I915_COMPONENT_H_
>  
> +/* MAX_PORT is the number of port
> + * It must be sync with I915_MAX_PORTS defined i915_drv.h
> + * 5 should be enough as only HSW, BDW, SKL need such fix.

You should probably add BUILD_BUG_ON(MAX_PORTS != I915_MAX_PORTS)
somewhere near the loop above. Or at least change I915_MAX_PORTS to
ARRAY_SIZE(acomp->aud_sample_rate) in the loop to not run over the array
if MAX_PORTS gets out of sync.

With that addressed one way or another, this is

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


> + */
> +#define MAX_PORTS 5
> +
>  struct i915_audio_component {
>  	struct device *dev;
> +	/**
> +	 * @aud_sample_rate: the array of audio sample rate per port
> +	 */
> +	int aud_sample_rate[MAX_PORTS];
>  
>  	const struct i915_audio_component_ops {
>  		struct module *owner;
> -- 
> 1.9.1
>

-- 
Jani Nikula, Intel Open Source Technology Center
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