linux-kernel - [PATCH] i2c: pxa: fix clang -Wvoid-pointer-to-enum-cast warning

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Message-ID: <20230816-void-drivers-i2c-busses-i2c-pxa-v1-1-931634b931ec@google.com>
Date:   Wed, 16 Aug 2023 19:48:23 +0000
From:   Justin Stitt <justinstitt@...gle.com>
To:     Andi Shyti <andi.shyti@...nel.org>,
        Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Tom Rix <trix@...hat.com>
Cc:     linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org,
        llvm@...ts.linux.dev, Justin Stitt <justinstitt@...gle.com>
Subject: [PATCH] i2c: pxa: fix clang -Wvoid-pointer-to-enum-cast warning

When building with clang 18 I see the following warning:
|       drivers/i2c/busses/i2c-pxa.c:1267:15: warning: cast to smaller integer
|       type 'enum pxa_i2c_types' from 'const void *' [-Wvoid-pointer-to-enum-cast]
|        1267 |         *i2c_types = (enum pxa_i2c_types)(of_id->data);

This is due to the fact that `of_id->data` is a void* while `enum pxa_i2c_types`
has the size of an int.

Cast `of_id->data` to a uintptr_t to silence the above warning for clang
builds using W=1

Link: https://github.com/ClangBuiltLinux/linux/issues/1910
Reported-by: Nathan Chancellor <nathan@...nel.org>
Signed-off-by: Justin Stitt <justinstitt@...gle.com>
---
Note: I think something like this may be more readable:
| 	*i2c_types = (enum pxa_i2c_types)(uintptr_t)of_id->data;

Thoughts on this approach against the one present in this patch?
---
 drivers/i2c/busses/i2c-pxa.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/i2c/busses/i2c-pxa.c b/drivers/i2c/busses/i2c-pxa.c
index 937f7eebe906..20d1132d3d69 100644
--- a/drivers/i2c/busses/i2c-pxa.c
+++ b/drivers/i2c/busses/i2c-pxa.c
@@ -1264,7 +1264,7 @@ static int i2c_pxa_probe_dt(struct platform_device *pdev, struct pxa_i2c *i2c,
 	i2c->use_pio = of_property_read_bool(np, "mrvl,i2c-polling");
 	i2c->fast_mode = of_property_read_bool(np, "mrvl,i2c-fast-mode");
 
-	*i2c_types = (enum pxa_i2c_types)(of_id->data);
+	*i2c_types = (uintptr_t)of_id->data;
 
 	return 0;
 }

---
base-commit: 2ccdd1b13c591d306f0401d98dedc4bdcd02b421
change-id: 20230816-void-drivers-i2c-busses-i2c-pxa-aaf94f5c39e0

Best regards,
--
Justin Stitt <justinstitt@...gle.com>