Re: [PATCH 1/4] ASoC: qcom: audioreach: compute active channel maps from channel_map

[Srinivas Kandagatla <srini@kernel.org>]

On 6/10/26 8:41 AM, Neil Armstrong wrote:
> The Qualcom SM8650 based Ayaneo Pocket S2 gaming device has a set
> of 2 WSA speakers connected on the WSA2 lines.
> 
> But the Audioreach DSP only handles WSA2 in pair with the WSA
> interface by using the upper bits of the active_channels_mask
> for WSA2 and the lower bits for WSA:
> 
> /-------------------------------------------------\
> | Bits  |     3    |     2    |   1     |     0   |
> |-------------------------------------------------|
> | Line  | WSA2 Ch2 | WSA2 Ch1 | WSA Ch2 | WSA Ch1 |
> \-------------------------------------------------/
> 
No, this is not totally correct, if the setup only has WSA2, then
channel 0 and 1 should be WSA2 channels.

What is the backend dai id that is in DT, it should be

	sound-dai = <&q6apmbedai WSA2_CODEC_DMA_RX_0>;

I also noticed that you are using
https://github.com/linux-msm/audioreach-topology/blob/main/SM8550-HDK.m4
which has WSA as backend dai, that is not correct, you should have WSA2.


> Setting only the WSA2 upper bits is perfectly valid and
> functional but the current Audioreach code builds the bitmask
> from the channels count with:
> 	active_channels_mask = (1 << num_channels) - 1;
> 
> In order to enable the WSA2 bits the channel count should be 4,
> but the lower WSA bits are then also enabled and the DSP errors
> out when trying to play on the disabled WSA interface.
> 
> A solution would've been to add a fake WSA2 topology element which
> would be translated into the top bits only, but it's not clean and
> add some special exceptions in the generic Audioreach code.
> 
> The solution suggested by Srinivas is to use the channel mapping to
> set this bitmask.
> 
> This works but makes all the other calls using the channel mapping fail
> because the DSP requires the channel_mapping table to start from index 0
> and using num_channel length in order to apply the mapping on the
> active_channels_mask bits in order.
> 
> So we need to skip the empty channel mapping entries in all other
> users of the channel_map to build valid channel_mapping tables.
> 
> This should not break any other usecases since the default channel
> mapping always start from index 0, and will add flexibilty to allow
> some special non linear mapping for other interfaces as well.
> 
> Suggested-by: Srinivas Kandagatla <srinivas.kandagatla@oss.qualcomm.com>
> Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
> ---
>  sound/soc/qcom/qdsp6/audioreach.c | 47 ++++++++++++++++++++++++++++++---------
>  1 file changed, 37 insertions(+), 10 deletions(-)
> 
> diff --git a/sound/soc/qcom/qdsp6/audioreach.c b/sound/soc/qcom/qdsp6/audioreach.c
> index a13f753eff98..9b80cfa56e8a 100644
> --- a/sound/soc/qcom/qdsp6/audioreach.c
> +++ b/sound/soc/qcom/qdsp6/audioreach.c
> @@ -703,6 +703,7 @@ static int audioreach_codec_dma_set_media_format(struct q6apm_graph *graph,
>  	int pm_sz = APM_HW_EP_PMODE_CFG_PSIZE;
>  	int size = ic_sz + ep_sz + fs_sz + pm_sz;
>  	void *p;
> +	int i;
>  
>  	struct gpr_pkt *pkt __free(kfree) = audioreach_alloc_apm_cmd_pkt(size, APM_CMD_SET_CFG, 0);
>  	if (IS_ERR(pkt))
> @@ -741,7 +742,12 @@ static int audioreach_codec_dma_set_media_format(struct q6apm_graph *graph,
>  
>  	intf_cfg->cfg.lpaif_type = module->hw_interface_type;
>  	intf_cfg->cfg.intf_index = module->hw_interface_idx;
> -	intf_cfg->cfg.active_channels_mask = (1 << cfg->num_channels) - 1;
> +	intf_cfg->cfg.active_channels_mask = 0;
> +	/* Convert the physical channel mapping into a bit field */
> +	for (i = 0; i < AR_PCM_MAX_NUM_CHANNEL; i++)
> +		if (cfg->channel_map[i])
> +			intf_cfg->cfg.active_channels_mask |= BIT(i);
> +

This one looks good, this should be a bug fix patch.

>  	p += ic_sz;
>  
>  	pm_cfg = p;
> @@ -840,7 +846,7 @@ static int audioreach_mfc_set_media_format(struct q6apm_graph *graph,
>  	uint32_t num_channels = cfg->num_channels;
>  	int payload_size = APM_MFC_CFG_PSIZE(media_format, num_channels) +
>  				APM_MODULE_PARAM_DATA_SIZE;
> -	int i;
> +	int i, j;
>  	void *p;
>  
>  	struct gpr_pkt *pkt __free(kfree) = audioreach_alloc_apm_cmd_pkt(payload_size, APM_CMD_SET_CFG, 0);
> @@ -860,8 +866,12 @@ static int audioreach_mfc_set_media_format(struct q6apm_graph *graph,
>  	media_format->sample_rate = cfg->sample_rate;
>  	media_format->bit_width = cfg->bit_width;
>  	media_format->num_channels = cfg->num_channels;
> -	for (i = 0; i < num_channels; i++)
> -		media_format->channel_mapping[i] = cfg->channel_map[i];
> +	/* Convert the physical mapping to a logical mapping of the channels */
> +	for (i = 0, j = 0; i < AR_PCM_MAX_NUM_CHANNEL && j < cfg->num_channels; i++) {
> +		if (!cfg->channel_map[i])
> +			continue;
> +		media_format->channel_mapping[j++] = cfg->channel_map[i];
Each element i of the channel_mapping[i] array, describes the channel i
inside the buffer where i is less than num_channels.  An unused channel
is set to 0.

For some reason I get impression that user is trying to set a 4 channels
instead of 2 channel.

Can you fix the backend-dai id and play it directly on WSA2 instead of WSA.
Or was there a reason for not doing it otherwise?

--srini

> +	}
>  
>  	return q6apm_send_cmd_sync(graph->apm, pkt, 0);
>  }
> @@ -1080,6 +1090,7 @@ static int audioreach_pcm_set_media_format(struct q6apm_graph *graph,
>  	struct apm_pcm_module_media_fmt_cmd *cfg;
>  	struct apm_module_param_data *param_data;
>  	int payload_size;
> +	int i, j;
>  
>  	if (num_channels > 4) {
>  		dev_err(graph->dev, "Error: Invalid channels (%d)!\n", num_channels);
> @@ -1113,7 +1124,12 @@ static int audioreach_pcm_set_media_format(struct q6apm_graph *graph,
>  	media_cfg->num_channels = mcfg->num_channels;
>  	media_cfg->q_factor = mcfg->bit_width - 1;
>  	media_cfg->bits_per_sample = mcfg->bit_width;
> -	memcpy(media_cfg->channel_mapping, mcfg->channel_map, mcfg->num_channels);
> +	/* Convert the physical mapping to a logical mapping of the channels */
> +	for (i = 0, j = 0; i < AR_PCM_MAX_NUM_CHANNEL && j < mcfg->num_channels; i++) {
> +		if (!mcfg->channel_map[i])
> +			continue;
> +		media_cfg->channel_mapping[j++] = mcfg->channel_map[i];
> +	}
>  
>  	return q6apm_send_cmd_sync(graph->apm, pkt, 0);
>  }
> @@ -1127,6 +1143,7 @@ static int audioreach_shmem_set_media_format(struct q6apm_graph *graph,
>  	struct payload_media_fmt_pcm *cfg;
>  	struct media_format *header;
>  	int rc, payload_size;
> +	int i, j;
>  	void *p;
>  
>  	if (num_channels > 4) {
> @@ -1166,7 +1183,12 @@ static int audioreach_shmem_set_media_format(struct q6apm_graph *graph,
>  		cfg->q_factor = mcfg->bit_width - 1;
>  		cfg->endianness = PCM_LITTLE_ENDIAN;
>  		cfg->num_channels = mcfg->num_channels;
> -		memcpy(cfg->channel_mapping, mcfg->channel_map, mcfg->num_channels);
> +		/* Convert the physical mapping to a logical mapping of the channels */
> +		for (i = 0, j = 0; i < AR_PCM_MAX_NUM_CHANNEL && j < cfg->num_channels; i++) {
> +			if (!mcfg->channel_map[i])
> +				continue;
> +			cfg->channel_mapping[j++] = mcfg->channel_map[i];
> +		}
>  	} else {
>  		rc = audioreach_set_compr_media_format(header, p, mcfg);
>  		if (rc)
> @@ -1243,7 +1265,7 @@ static int audioreach_speaker_protection_vi(struct q6apm_graph *graph,
>  	struct apm_module_sp_vi_ex_mode_cfg *ex_cfg;
>  	int op_sz, cm_sz, ex_sz;
>  	struct apm_module_param_data *param_data;
> -	int rc, i, payload_size;
> +	int rc, i, payload_size, j;
>  	struct gpr_pkt *pkt;
>  	void *p;
>  
> @@ -1284,14 +1306,19 @@ static int audioreach_speaker_protection_vi(struct q6apm_graph *graph,
>  	param_data->param_size = cm_sz - APM_MODULE_PARAM_DATA_SIZE;
>  
>  	cm_cfg->cfg.num_channels = num_channels * 2;
> -	for (i = 0; i < num_channels; i++) {
> +	/* Convert the physical mapping to a logical mapping of the channels */
> +	for (i = 0, j = 0; i < AR_PCM_MAX_NUM_CHANNEL && j < num_channels; i++) {
> +		if (!mcfg->channel_map[i])
> +			continue;
>  		/*
>  		 * Map speakers into Vsense and then Isense of each channel.
>  		 * E.g. for PCM_CHANNEL_FL and PCM_CHANNEL_FR to:
>  		 * [1, 2, 3, 4]
>  		 */
> -		cm_cfg->cfg.channel_mapping[2 * i] = (mcfg->channel_map[i] - 1) * 2 + 1;
> -		cm_cfg->cfg.channel_mapping[2 * i + 1] = (mcfg->channel_map[i] - 1) * 2 + 2;
> +		cm_cfg->cfg.channel_mapping[2 * j] = (mcfg->channel_map[i] - 1) * 2 + 1;
> +		cm_cfg->cfg.channel_mapping[2 * j + 1] = (mcfg->channel_map[i] - 1) * 2 + 2;
> +
> +		++j;
>  	}
>  
>  	p += cm_sz;
>