Re: [PATCH v2 1/3] driver core: platform: Add the helper function devm_platform_get_and_ioremap_resource_byname()

On Thu, Sep 02, 2021 at 04:05:39PM +0800, Cai Huoqing wrote:

On 02 Sep 21 08:52:45, Greg KH wrote:

quoted

On Thu, Sep 02, 2021 at 02:37:00PM +0800, Cai Huoqing wrote:

quoted

Since provide the helper function devm_platform_ioremap_resource_byname()
which is wrap platform_get_resource_byname() and devm_ioremap_resource().
But sometimes, many drivers still need to use the resource variables
obtained by platform_get_resource(). In these cases, provide this helper
function devm_platform_get_and_ioremap_resource_byname().

Signed-off-by: Cai Huoqing <redacted>
---
v1->v2: Resend this patch as part of a patch series that uses
	the new function. 

 drivers/base/platform.c         | 30 ++++++++++++++++++++++++++----
 include/linux/platform_device.h |  3 +++
 2 files changed, 29 insertions(+), 4 deletions(-)

diff --git a/drivers/base/platform.c b/drivers/base/platform.c
index 652531f67135..34bb581338d9 100644
--- a/drivers/base/platform.c
+++ b/drivers/base/platform.c

@@ -124,6 +124,31 @@ void __iomem *devm_platform_ioremap_resource(struct platform_device *pdev,
 }
 EXPORT_SYMBOL_GPL(devm_platform_ioremap_resource);
 
+/**
+ * devm_platform_get_and_ioremap_resource_byname - call devm_ioremap_resource() for a
+ *						   platform device and get resource
+ *
+ * @pdev: platform device to use both for memory resource lookup as well as
+ *        resource management
+ * @name: name of the resource
+ * @res: optional output parameter to store a pointer to the obtained resource.
+ *
+ * Return: a pointer to the remapped memory or an ERR_PTR() encoded error code
+ * on failure.
+ */
+void __iomem *
+devm_platform_get_and_ioremap_resource_byname(struct platform_device *pdev,
+					      const char *name, struct resource **res)
+{
+	struct resource *r;
+
+	r = platform_get_resource_byname(pdev, IORESOURCE_MEM, name);
+	if (res)
+		*res = r;

You forgot to check the return value of this call :(

devm_ioremap_resource wiil check it and print error message, here:
./lib/devres.c:136:__devm_ioremap_resource(

	if (!res || resource_type(res) != IORESOURCE_MEM) {
		dev_err(dev, "invalid resource\n");
		return IOMEM_ERR_PTR(-EINVAL);

And then you move on and use the resource :(

Please properly test your code.

quoted

Which means you did not test this?  Why not?

But step back, _WHY_ is this needed at all?  How deep are we going to
get with the "devm_platform_get_and_do_this_and_that_and_that" type
functions here?

  the function name seems too long, how can I rename it:)

You have not shown a requirement that this new function is needed at
all.

Why are you making this change?  Why do you want to do this?  What is it
helping out with?

thanks,

greg k-h

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