media: venus: Limit HFI sessions to the maximum supported

Currently we rely on firmware to return error when we reach the maximum
supported number of sessions. But this errors are happened at reqbuf
time which is a bit later. The more reasonable way looks like is to
return the error on driver open.

To achieve that modify hfi_session_create to return error when we reach
maximum count of sessions and thus refuse open.
Tested-by: Fritz Koenig <frkoenig@chromium.org>
Signed-off-by: Stanimir Varbanov <stanimir.varbanov@linaro.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

drivers/media/platform/qcom/venus/core.h

@@ -96,6 +96,7 @@ struct venus_format {
 #define MAX_CAP_ENTRIES		32
 #define MAX_ALLOC_MODE_ENTRIES	16
 #define MAX_CODEC_NUM		32
+#define MAX_SESSIONS		16
 
 struct raw_formats {
 	u32 buftype;

drivers/media/platform/qcom/venus/hfi.c

@@ -175,6 +175,8 @@ static int wait_session_msg(struct venus_inst *inst)
 int hfi_session_create(struct venus_inst *inst, const struct hfi_inst_ops *ops)
 {
 	struct venus_core *core = inst->core;
+	bool max;
+	int ret;
 
 	if (!ops)
 		return -EINVAL;
@@ -184,11 +186,19 @@ int hfi_session_create(struct venus_inst *inst, const struct hfi_inst_ops *ops)
 	inst->ops = ops;
 
 	mutex_lock(&core->lock);
-	list_add_tail(&inst->list, &core->instances);
-	atomic_inc(&core->insts_count);
+
+	max = atomic_add_unless(&core->insts_count, 1,
+				core->max_sessions_supported);
+	if (!max) {
+		ret = -EAGAIN;
+	} else {
+		list_add_tail(&inst->list, &core->instances);
+		ret = 0;
+	}
+
 	mutex_unlock(&core->lock);
 
-	return 0;
+	return ret;
 }
 EXPORT_SYMBOL_GPL(hfi_session_create);
 

drivers/media/platform/qcom/venus/hfi_parser.c

@@ -276,6 +276,9 @@ u32 hfi_parser(struct venus_core *core, struct venus_inst *inst, void *buf,
 		words_count--;
 	}
 
+	if (!core->max_sessions_supported)
+		core->max_sessions_supported = MAX_SESSIONS;
+
 	parser_fini(inst, codecs, domain);
 
 	return HFI_ERR_NONE;