[Intel-gfx] [PATCH] drm/i915/display: compute config for audio
Jani Nikula
jani.nikula at linux.intel.com
Wed Aug 24 13:56:56 UTC 2022
On Wed, 24 Aug 2022, "Borah, Chaitanya Kumar" <chaitanya.kumar.borah at intel.com> wrote:
> In certain scenarios, we might have to filter out some audio
> configuration depending on HW limitation. For example, in
> GLK DP port more than 2 channels are not supported for audio.
> A monitor provides information of it's supported audio configurations
> through SAD (Short Audio Descriptors) which are part of the ELD/EDID.
> In this patch we add a bit mask to indicate which SADs are supported.
> The bit mask is updated in the function intel_eld_compute_config().
> Based on this bit mask, we prune SADs which are not supported in
> the function i915_audio_component_get_eld() before sending out the
> data to the audio driver.
>
> We use a bit mask instead of operating on the eld data directly as
> eld data can get updated after intel_eld_compute_config() and before
> i915_audio_component_get_eld() is called
>
> fixes: https://gitlab.freedesktop.org/drm/intel/-/issues/5368
>
> Signed-off-by: Borah, Chaitanya Kumar <chaitanya.kumar.borah at intel.com>
> ---
> drivers/gpu/drm/drm_edid.c | 36 ++++++++++
> drivers/gpu/drm/i915/display/intel_audio.c | 65 ++++++++++++++++++-
> drivers/gpu/drm/i915/display/intel_audio.h | 3 +
> drivers/gpu/drm/i915/display/intel_ddi.c | 2 +
> .../drm/i915/display/intel_display_types.h | 9 +++
> include/drm/drm_edid.h | 9 +++
First of all, drm_edid.[ch] and i915 changes need to be separated.
> 6 files changed, 123 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> index 90a5e26eafa8..3495af8d8596 100644
> --- a/drivers/gpu/drm/drm_edid.c
> +++ b/drivers/gpu/drm/drm_edid.c
> @@ -6988,3 +6988,39 @@ static void _drm_update_tile_info(struct drm_connector *connector,
> connector->tile_group = NULL;
> }
> }
> +
> +/*
> + * drm_sad_to_format - extract format of an SAD
> + * @sad: pointer to an sad
> + *
> + * extract the format of an SAD from byte 0
> + */
> +int drm_sad_to_format(const u8 *sad)
> +{
> + return (sad[0] & DRM_ELD_SAD_FORMAT_MASK) >> DRM_ELD_SAD_FORMAT_SHIFT;
> +}
> +EXPORT_SYMBOL(drm_sad_to_format);
> +
> +/*
> + * drm_sad_to_format - extract channels of an SAD
> + * @sad: pointer to an sad
> + *
> + * extract number of supported channels from byte 0 of SAD
> + */
> +int drm_sad_to_channels(const u8 *sad)
> +{
> + return (sad[0] & DRM_ELD_SAD_CHANNELS_MASK) + 1;
> +}
> +EXPORT_SYMBOL(drm_sad_to_channels);
> +
> +/*
> + * drm_sad_to_format - extract supported rates of an SAD
> + * @sad: pointer to an sad
> + *
> + * extract supported rates from byte 1 of SAD
> + */
> +int drm_sad_to_rates(const u8 *sad)
> +{
> + return sad[1] & DRM_ELD_SAD_RATES_MASK;
> +}
> +EXPORT_SYMBOL(drm_sad_to_rates);
Not enthusiastic about adding a bunch of new functions to inspect the
sad here. Makes me think this should be parsed and stored in
drm_display_info in drm_edid_to_eld() instead if it's generally useful
data.
> diff --git a/drivers/gpu/drm/i915/display/intel_audio.c b/drivers/gpu/drm/i915/display/intel_audio.c
> index 6c9ee905f132..ac425b652331 100644
> --- a/drivers/gpu/drm/i915/display/intel_audio.c
> +++ b/drivers/gpu/drm/i915/display/intel_audio.c
> @@ -1235,7 +1235,33 @@ static int i915_audio_component_get_eld(struct device *kdev, int port,
> if (*enabled) {
> eld = intel_encoder->audio_connector->eld;
> ret = drm_eld_size(eld);
> - memcpy(buf, eld, min(max_bytes, ret));
> +
> + if (intel_encoder->sad_mask_valid) {
> + int i;
> + u8 *temp_buf;
> + u8 *sad;
> +
> + temp_buf = kzalloc(ret, GFP_KERNEL);
> +
> + if (!temp_buf) {
> + mutex_unlock(&dev_priv->audio.mutex);
> + return -ENOMEM;
Please no error returns like this; use goto and common exit handling
with the unlock.
> + }
> +
> + memcpy(temp_buf, eld, ret);
> +
> + sad = (u8 *)drm_eld_sad(temp_buf);
This may return NULL. And cringe about casting const away.
> +
> + for (i = 0; i < drm_eld_sad_count(temp_buf); i++, sad += 3) {
> + if (!(intel_encoder->supported_sads & (1 << i)))
> + memset(&sad[0], 0, 3);
Here's the main question I have about the change, really. The ELD
(literally EDID-like-data) and SAD are supposed to describe the *sink*
capabilities. Why are we filtering the data here, telling the audio
controller driver this is what the *sink* supports, when the limitation
comes from the *source*?
I could just be clueless about how audio works, but semantically this
feels the same as modifying the EDID based on what the *source*
supports.
> + }
> +
> + memcpy(buf, temp_buf, min(max_bytes, ret));
> + kfree(temp_buf);
> + } else {
> + memcpy(buf, eld, min(max_bytes, ret));
> + }
> }
>
> mutex_unlock(&dev_priv->audio.mutex);
> @@ -1408,3 +1434,40 @@ void intel_audio_deinit(struct drm_i915_private *dev_priv)
> else
> i915_audio_component_cleanup(dev_priv);
> }
> +
> +void intel_eld_compute_config(struct intel_encoder *encoder,
> + const struct intel_crtc_state *pipe_config,
> + const struct drm_connector_state *conn_state)
It should probably be named intel_audio_compute_config().
> +{
> + struct drm_connector *connector = conn_state->connector;
> + u8 *eld = connector->eld;
> + const u8 *sad = drm_eld_sad(eld);
> + struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
Should be named i915 for all new code.
> + u32 *supported_sads = &encoder->supported_sads;
> + int i, channels;
> +
> + mutex_lock(&dev_priv->audio.mutex);
> +
> + /* reset information about supported sads to default */
> + *supported_sads = 0;
> + encoder->sad_mask_valid = false;
> +
> + /* Currently filtering SADs is necessary only for GLK due to it's
> + * hardware limitations. However, this function can be scaled
> + * to any scenario where display driver has to filter out certain
> + * SADs before exposing them to the audio driver.
> + */
> + if (IS_GEMINILAKE(dev_priv) &&
> + intel_crtc_has_type(pipe_config, INTEL_OUTPUT_DP)) {
> + encoder->sad_mask_valid = true;
> +
> + for (i = 0; i < drm_eld_sad_count(eld); i++, sad += 3) {
> + channels = drm_sad_to_channels(sad);
> +
> + if (channels <= 2)
> + (*supported_sads) |= 1 << i;
> + }
> + }
It's wrong to modify the encoder members in compute config. Just imagine
compute config failing after this; you've already changed the encoder
and you can't get it back.
> + drm_dbg_kms(&dev_priv->drm, "supported_sads 0x%x\n", *supported_sads);
> + mutex_unlock(&dev_priv->audio.mutex);
The indentation is off in the function.
BR,
Jani.
> +}
> diff --git a/drivers/gpu/drm/i915/display/intel_audio.h b/drivers/gpu/drm/i915/display/intel_audio.h
> index 63b22131dc45..17c468a9e07e 100644
> --- a/drivers/gpu/drm/i915/display/intel_audio.h
> +++ b/drivers/gpu/drm/i915/display/intel_audio.h
> @@ -22,5 +22,8 @@ void intel_audio_cdclk_change_pre(struct drm_i915_private *dev_priv);
> void intel_audio_cdclk_change_post(struct drm_i915_private *dev_priv);
> void intel_audio_init(struct drm_i915_private *dev_priv);
> void intel_audio_deinit(struct drm_i915_private *dev_priv);
> +void intel_eld_compute_config(struct intel_encoder *encoder,
> + const struct intel_crtc_state *pipe_config,
> + const struct drm_connector_state *conn_state);
>
> #endif /* __INTEL_AUDIO_H__ */
> diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c b/drivers/gpu/drm/i915/display/intel_ddi.c
> index 6c43a5124cb8..e7807500c88d 100644
> --- a/drivers/gpu/drm/i915/display/intel_ddi.c
> +++ b/drivers/gpu/drm/i915/display/intel_ddi.c
> @@ -3678,6 +3678,8 @@ static int intel_ddi_compute_config(struct intel_encoder *encoder,
>
> intel_ddi_compute_min_voltage_level(dev_priv, pipe_config);
>
> + intel_eld_compute_config(encoder, pipe_config, conn_state);
> +
> return 0;
> }
>
> diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h
> index 0da9b208d56e..5b6a694ff0cc 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_types.h
> +++ b/drivers/gpu/drm/i915/display/intel_display_types.h
> @@ -265,6 +265,15 @@ struct intel_encoder {
> /* for communication with audio component; protected by av_mutex */
> const struct drm_connector *audio_connector;
>
> + /* bitmask to track supported SADs for current audio connector.
> + * According to HDA spec Rev 1.0a, ELD SAD limit is 15. Using
> + * a 32 bit mask for future proofing; protected by av_mutex
> + */
> + u32 supported_sads;
> +
> + /* indicates if the supported_sads is a valid bitmask; protected by av_mutex */
> + bool sad_mask_valid;
> +
> /* VBT information for this encoder (may be NULL for older platforms) */
> const struct intel_bios_encoder_data *devdata;
> };
> diff --git a/include/drm/drm_edid.h b/include/drm/drm_edid.h
> index 2181977ae683..363f4487cdd6 100644
> --- a/include/drm/drm_edid.h
> +++ b/include/drm/drm_edid.h
> @@ -318,6 +318,11 @@ struct detailed_timing {
>
> #define DRM_ELD_CEA_SAD(mnl, sad) (20 + (mnl) + 3 * (sad))
>
> +#define DRM_ELD_SAD_FORMAT_MASK 0x78
> +#define DRM_ELD_SAD_FORMAT_SHIFT 3
> +#define DRM_ELD_SAD_CHANNELS_MASK 0x7
> +#define DRM_ELD_SAD_RATES_MASK 0x7f
> +
> struct edid {
> u8 header[8];
> /* Vendor & product info */
> @@ -378,6 +383,10 @@ int drm_edid_to_speaker_allocation(const struct edid *edid, u8 **sadb);
> int drm_av_sync_delay(struct drm_connector *connector,
> const struct drm_display_mode *mode);
>
> +int drm_sad_to_format(const u8 *sad);
> +int drm_sad_to_channels(const u8 *sad);
> +int drm_sad_to_rates(const u8 *sad);
> +
> #ifdef CONFIG_DRM_LOAD_EDID_FIRMWARE
> struct edid *drm_load_edid_firmware(struct drm_connector *connector);
> int __drm_set_edid_firmware_path(const char *path);
--
Jani Nikula, Intel Open Source Graphics Center
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