linux-kernel - [PATCH] leds: pca955x: fix -Wvoid-pointer-to-enum-cast warning

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Message-ID: <20230816-void-drivers-leds-leds-pca955x-v1-1-2967e4c1bdcc@google.com>
Date:   Wed, 16 Aug 2023 19:37:52 +0000
From:   Justin Stitt <justinstitt@...gle.com>
To:     Pavel Machek <pavel@....cz>, Lee Jones <lee@...nel.org>,
        Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Tom Rix <trix@...hat.com>
Cc:     linux-leds@...r.kernel.org, linux-kernel@...r.kernel.org,
        llvm@...ts.linux.dev, Justin Stitt <justinstitt@...gle.com>
Subject: [PATCH] leds: pca955x: fix -Wvoid-pointer-to-enum-cast warning

When building with clang 18 I see the following warning:
|      drivers/leds/leds-pca955x.c:487:15: warning: cast to smaller integer
|      type 'enum pca955x_type' from 'const void *' [-Wvoid-pointer-to-enum-cast]
|        487 |                 chip_type = (enum pca955x_type)md;

This is due to the fact that `md` is a void* while `enum pca995x_type` has the
size of an int.

Add uintptr_t cast to silence clang warning while also keeping enum cast
for readability and consistency with other `chip_type` assignment just a
few lines below:
|	chip_type = (enum pca955x_type)id->driver_data;

Link: https://github.com/ClangBuiltLinux/linux/issues/1910
Reported-by: Nathan Chancellor <nathan@...nel.org>
Signed-off-by: Justin Stitt <justinstitt@...gle.com>
---


leds: pca955x: fix -Wvoid-pointer-to-enum-cast warning
---
Note: I've opted to keep the initial `enum pca955x_type` cast and just
place the uintptr_t cast first to silence the warning. It seemed weird
to me to see the same variable being assigned to two different casted
values within just a few lines.
---
 drivers/leds/leds-pca955x.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/leds/leds-pca955x.c b/drivers/leds/leds-pca955x.c
index b10e1ef38db0..1d7fa0cd97bf 100644
--- a/drivers/leds/leds-pca955x.c
+++ b/drivers/leds/leds-pca955x.c
@@ -484,7 +484,7 @@ static int pca955x_probe(struct i2c_client *client)
 	const void *md = device_get_match_data(&client->dev);
 
 	if (md) {
-		chip_type = (enum pca955x_type)md;
+		chip_type = (enum pca955x_type)(uintptr_t)md;
 	} else {
 		const struct i2c_device_id *id = i2c_match_id(pca955x_id,
 							      client);

---
base-commit: 2ccdd1b13c591d306f0401d98dedc4bdcd02b421
change-id: 20230816-void-drivers-leds-leds-pca955x-7002cc67a291

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