Subject: Re: [PATCH] net: mdio: fix -Wvoid-pointer-to-enum-cast warning

From: "Russell King (Oracle)" <[email-masked]>
Date: Wed, 16 Aug 2023 10:51:41 +0100

On Tue, Aug 15, 2023 at 10:41:39PM +0200, Andrew Lunn wrote:
> On Tue, Aug 15, 2023 at 08:35:59PM +0000, Justin Stitt wrote:
> > When building with clang 18 I see the following warning:
> > |       drivers/net/mdio/mdio-xgene.c:338:13: warning: cast to smaller integer
> > |               type 'enum xgene_mdio_id' from 'const void *' [-Wvoid-pointer-to-enum-cast]
> > |         338 |                 mdio_id = (enum xgene_mdio_id)of_id->data;
> > 
> > This is due to the fact that `of_id->data` is a void* while `enum
> > xgene_mdio_id` has the size of an int. This leads to truncation and
> > possible data loss.
> > 
> > Link: https://github.com/ClangBuiltLinux/linux/issues/1910
> > Reported-by: Nathan Chancellor <[email-masked]>
> > Signed-off-by: Justin Stitt <[email-masked]>
> 
> Reviewed-by: Andrew Lunn <[email-masked]>

I wonder whether it would be better to use device_get_match_data()
here? The whole of_match_device()...acpi_match_device() dance could
become:

+	mdio_id = (uintptr_t)device_get_match_data(&pdev->dev);
	if (!mdio_id)
		return -ENODEV;

It's probably something for a follow-up patch though.

Reviewed-by: Russell King (Oracle) <[email-masked]>

Thanks!

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