Re: [PATCH 1/2] ASoC: qcom: q6apm: Guard callbacks until probe data is ready

[Srinivas Kandagatla <srinivas.kandagatla@oss.qualcomm.com>]

On 10/22/26 3:41 PM, Mohit Sharma wrote:
> The GPR bus needs to make response callbacks available before invoking a
> client probe because clients can issue synchronous commands from probe.
> This creates a short interval where a callback can run before the client
> has published its private data.
> 
> Make q6apm publish its driver data only after all callback-visible state
> has been initialized. Have the q6apm and q6prm callbacks ignore packets
> received before driver data is available.
> 
> Fixes: ec1471a898cc ("soc: qcom: apr: Add GPR support")
> Cc: stable@vger.kernel.org
> Co-developed-by: Ajay Kumar Nandam <ajay.nandam@oss.qualcomm.com>
> Signed-off-by: Ajay Kumar Nandam <ajay.nandam@oss.qualcomm.com>
> Signed-off-by: Mohit Sharma <mohit.sharma@oss.qualcomm.com>
> ---
>  sound/soc/qcom/qdsp6/q6apm.c | 6 ++++--
>  sound/soc/qcom/qdsp6/q6prm.c | 3 +++
>  2 files changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/sound/soc/qcom/qdsp6/q6apm.c b/sound/soc/qcom/qdsp6/q6apm.c
> index 3ec3c5a18c7a..dbebb643cd5e 100644
> --- a/sound/soc/qcom/qdsp6/q6apm.c
> +++ b/sound/soc/qcom/qdsp6/q6apm.c
> @@ -872,8 +872,6 @@ static int apm_probe(gpr_device_t *gdev)
>  	if (!apm)
>  		return -ENOMEM;
>  
> -	dev_set_drvdata(dev, apm);
> -
>  	mutex_init(&apm->lock);
>  	apm->dev = dev;
>  	apm->gdev = gdev;
> @@ -887,6 +885,7 @@ static int apm_probe(gpr_device_t *gdev)
>  
>  	idr_init(&apm->modules_idr);
>  
> +	dev_set_drvdata(dev, apm);
>  	g_apm = apm;
>  
>  	q6apm_get_apm_state(apm);
> @@ -930,6 +929,9 @@ static int apm_callback(const struct gpr_resp_pkt *data, void *priv, int op)
>  	const struct gpr_hdr *hdr = &data->hdr;
>  	int graph_id, is_pos_buf;
>  
> +	if (!apm)
> +		return 0;
This is going to silently drop the responses. What are these packets?

> +
>  	result = data->payload;
>  
>  	switch (hdr->opcode) {
> diff --git a/sound/soc/qcom/qdsp6/q6prm.c b/sound/soc/qcom/qdsp6/q6prm.c
> index 2042ff1e8ff1..5c927ebd81f4 100644
> --- a/sound/soc/qcom/qdsp6/q6prm.c
> +++ b/sound/soc/qcom/qdsp6/q6prm.c
> @@ -194,6 +194,9 @@ static int prm_callback(const struct gpr_resp_pkt *data, void *priv, int op)
>  	const struct gpr_ibasic_rsp_result_t *result;
>  	const struct gpr_hdr *hdr = &data->hdr;
>  
> +	if (!prm)
> +		return 0;

This is going to silently drop the responses.
> +
>  	switch (hdr->opcode) {
>  	case PRM_CMD_RSP_REQUEST_HW_RSC:
>  	case PRM_CMD_RSP_RELEASE_HW_RSC: