linux-kernel - [PATCH 1/2] i2c: i2c-bcm-iproc: fix -Wvoid-pointer-to-enum-cast warning

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Date:   Wed, 09 Aug 2023 21:25:35 +0000
From:   Justin Stitt <justinstitt@...gle.com>
To:     Andi Shyti <andi.shyti@...nel.org>, Ray Jui <rjui@...adcom.com>,
        Scott Branden <sbranden@...adcom.com>,
        Broadcom internal kernel review list 
        <bcm-kernel-feedback-list@...adcom.com>
Cc:     linux-i2c@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, llvm@...ts.linux.dev,
        Nathan Chancellor <nathan@...nel.org>,
        Justin Stitt <justinstitt@...gle.com>
Subject: [PATCH 1/2] i2c: i2c-bcm-iproc: fix -Wvoid-pointer-to-enum-cast warning

When building with W=1 we see the following warning:

|  drivers/i2c/busses/i2c-bcm-iproc.c:1039:3: error: cast to smaller \
|       integer type 'enum bcm_iproc_i2c_type' from 'const void *' [-Werror,-Wvoid-pointer-to-enum-cast]
|   1039 |                 (enum bcm_iproc_i2c_type)of_device_get_match_data(&pdev->dev);
|        |                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

This is due to the fact that the `bcm_iproc_i2c_type` enum members are
int-width and a cast from pointer-width down to int will cause
truncation and possible data loss. Although in this case `bcm_iproc_i2c_type`
has only a few enumerated fields and thus there is likely no data loss
occurring. Nonetheless, this patch is necessary to the goal of promoting
this warning out of W=1.

Link: https://github.com/ClangBuiltLinux/linux/issues/1903
Signed-off-by: Justin Stitt <justinstitt@...gle.com>
---
 drivers/i2c/busses/i2c-bcm-iproc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/i2c/busses/i2c-bcm-iproc.c b/drivers/i2c/busses/i2c-bcm-iproc.c
index 2d8342fdc25d..3464f3a376a5 100644
--- a/drivers/i2c/busses/i2c-bcm-iproc.c
+++ b/drivers/i2c/busses/i2c-bcm-iproc.c
@@ -1036,7 +1036,7 @@ static int bcm_iproc_i2c_probe(struct platform_device *pdev)
 	platform_set_drvdata(pdev, iproc_i2c);
 	iproc_i2c->device = &pdev->dev;
 	iproc_i2c->type =
-		(enum bcm_iproc_i2c_type)of_device_get_match_data(&pdev->dev);
+		(unsigned long) of_device_get_match_data(&pdev->dev);
 	init_completion(&iproc_i2c->done);
 
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);

-- 
2.41.0.640.ga95def55d0-goog