Re: [PATCH V2 1/2] soc: qcom: aoss: Expose send for generic usecase

From: Deepak Kumar Singh
Date: Wed May 05 2021 - 03:44:53 EST

On 4/14/2021 2:42 AM, Bjorn Andersson wrote:
On Thu 08 Apr 23:39 CDT 2021, Deepak Kumar Singh wrote:
+ * qmp_get() - get a qmp handle from a device
+ * @dev: client device pointer
+ *
+ * Return: handle to qmp device on success, ERR_PTR() on failure
+ */
+struct qmp *qmp_get(struct device *dev)
+ struct platform_device *pdev;
+ struct device_node *np;
+ struct qmp *qmp;
+ if (!dev || !dev->of_node)
+ return ERR_PTR(-EINVAL);
+ np = of_parse_phandle(dev->of_node, "qcom,qmp", 0);
+ if (!np)
+ return ERR_PTR(-ENODEV);
+ pdev = of_find_device_by_node(np);
+ if (!pdev)
+ return ERR_PTR(-EINVAL);
+ qmp = platform_get_drvdata(pdev);
+ return qmp ? qmp : ERR_PTR(-EPROBE_DEFER);
+void qmp_put(struct platform_device *pdev)
+ platform_device_put(pdev);
I was expecting that the devres allocated struct qmp would stick around
until the struct device's release callback came. As described in my
answer to Mani yesterday I was wrong.

As such you need to make sure that struct qmp stays around until
qmp_remove() and all qmp_put() calls has been made.

I presume a reasonable way to achieve this is to not use devm to
allocate our struct qmp, add a kref to the object. So this would have to
be a kref_put() on that instead of the platform_device_put() I asked you
to implement here.

Sorry about that.

The rest of the patch looks good.


Hi Bjorn,

Even if we use kref_put(), would it not require platform_device_put()? As per my understanding of_find_device_by_node(np) will increment node/pdev kobj refcount which both needs to be decremented.