[PATCH v2 1/6] ASoC: qcom: qdsp6: q6afe: fix clk vote response type mismatch

[Val Packett <val@packett.cool>]

The response sent by the firmware when requesting a clock vote (opcode
AFE_CMD_RSP_REMOTE_LPASS_CORE_HW_VOTE_REQUEST) does not actually have
the same opcode + status payload as APR_BASIC_RSP_RESULT. Rather, it
returns one single u32 which is the client_handle that must be used in
future unvote requests for the same clock.

As a result of this type confusion, the status returned by the callback
to q6afe_vote_lpass_core_hw was actually an out-of-bounds read. It was
only interpreted as success (0) most of the time due to luck, but there
are some reports of random errors such as:

[   20.961100] qcom-q6afe aprsvc:service:4:4: AFE failed to vote (3)
[   20.961131] Failed to prepare clk 'core': -110

Fix by correctly interpreting the response as a single u32, and actually
store it as the client_handle to ensure unvote would work correctly.

Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/all/5976946.DvuYhMxLoT@antlia/
Fixes: 55e07531d922 ("ASoC: q6dsp: q6afe: add lpass hw voting support")
Reviewed-by: Srinivas Kandagatla <srinivas.kandagatla@oss.qualcomm.com>
Signed-off-by: Val Packett <val@packett.cool>
---
 sound/soc/qcom/qdsp6/q6afe.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/sound/soc/qcom/qdsp6/q6afe.c b/sound/soc/qcom/qdsp6/q6afe.c
index 40237267fda0..28b5b6b91897 100644
--- a/sound/soc/qcom/qdsp6/q6afe.c
+++ b/sound/soc/qcom/qdsp6/q6afe.c
@@ -379,6 +379,7 @@ struct q6afe {
 	struct q6core_svc_api_info ainfo;
 	struct mutex lock;
 	struct aprv2_ibasic_rsp_result_t result;
+	uint32_t vote_result;
 	wait_queue_head_t wait;
 	struct list_head port_list;
 	spinlock_t port_list_lock;
@@ -968,13 +969,14 @@ static int q6afe_callback(struct apr_device *adev, const struct apr_resp_pkt *da
 	const struct aprv2_ibasic_rsp_result_t *res;
 	const struct apr_hdr *hdr = &data->hdr;
 	struct q6afe_port *port;
+	uint32_t *vote_res;
 
 	if (!data->payload_size)
 		return 0;
 
-	res = data->payload;
 	switch (hdr->opcode) {
 	case APR_BASIC_RSP_RESULT: {
+		res = data->payload;
 		if (res->status) {
 			dev_err(afe->dev, "cmd = 0x%x returned error = 0x%x\n",
 				res->opcode, res->status);
@@ -1001,8 +1003,10 @@ static int q6afe_callback(struct apr_device *adev, const struct apr_resp_pkt *da
 	}
 		break;
 	case AFE_CMD_RSP_REMOTE_LPASS_CORE_HW_VOTE_REQUEST:
+		vote_res = data->payload;
 		afe->result.opcode = hdr->opcode;
-		afe->result.status = res->status;
+		afe->result.status = 0;
+		afe->vote_result = *vote_res;
 		wake_up(&afe->wait);
 		break;
 	default:
@@ -1899,6 +1903,8 @@ int q6afe_vote_lpass_core_hw(struct device *dev, uint32_t hw_block_id,
 			       AFE_CMD_RSP_REMOTE_LPASS_CORE_HW_VOTE_REQUEST);
 	if (ret)
 		dev_err(afe->dev, "AFE failed to vote (%d)\n", hw_block_id);
+	else
+		*client_handle = afe->vote_result;
 
 	return ret;
 }
-- 
2.53.0