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From: Justin Stitt <justinstitt@google.com>
To: Andi Shyti <andi.shyti@kernel.org>, Ray Jui <rjui@broadcom.com>,
	Scott Branden <sbranden@broadcom.com>,
	Broadcom internal kernel review list 
	<bcm-kernel-feedback-list@broadcom.com>
Cc: linux-i2c@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, llvm@lists.linux.dev,
	Nathan Chancellor <nathan@kernel.org>,
	Justin Stitt <justinstitt@google.com>
Subject: [PATCH 1/2] i2c: i2c-bcm-iproc: fix -Wvoid-pointer-to-enum-cast warning
Date: Wed, 09 Aug 2023 21:25:35 +0000	[thread overview]
Message-ID: <20230809-cbl-1903-v1-1-df9d66a3ba3e@google.com> (raw)
In-Reply-To: <20230809-cbl-1903-v1-0-df9d66a3ba3e@google.com>

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@google.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


WARNING: multiple messages have this Message-ID (diff)
From: Justin Stitt <justinstitt@google.com>
To: Andi Shyti <andi.shyti@kernel.org>, Ray Jui <rjui@broadcom.com>,
	 Scott Branden <sbranden@broadcom.com>,
	 Broadcom internal kernel review list
	<bcm-kernel-feedback-list@broadcom.com>
Cc: linux-i2c@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	 linux-kernel@vger.kernel.org, llvm@lists.linux.dev,
	 Nathan Chancellor <nathan@kernel.org>,
	Justin Stitt <justinstitt@google.com>
Subject: [PATCH 1/2] i2c: i2c-bcm-iproc: fix -Wvoid-pointer-to-enum-cast warning
Date: Wed, 09 Aug 2023 21:25:35 +0000	[thread overview]
Message-ID: <20230809-cbl-1903-v1-1-df9d66a3ba3e@google.com> (raw)
In-Reply-To: <20230809-cbl-1903-v1-0-df9d66a3ba3e@google.com>

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@google.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


_______________________________________________
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linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  reply	other threads:[~2023-08-09 21:25 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-08-09 21:25 [PATCH 0/2] i2c: fix -Wvoid-pointer-to-enum-cast warnings Justin Stitt
2023-08-09 21:25 ` Justin Stitt
2023-08-09 21:25 ` Justin Stitt [this message]
2023-08-09 21:25   ` [PATCH 1/2] i2c: i2c-bcm-iproc: fix -Wvoid-pointer-to-enum-cast warning Justin Stitt
2023-08-10  8:56   ` Andi Shyti
2023-08-10  8:56     ` Andi Shyti
2023-08-10 14:44     ` Nathan Chancellor
2023-08-10 14:44       ` Nathan Chancellor
2023-08-09 21:25 ` [PATCH 2/2] i2c: i2c-rcar: " Justin Stitt
2023-08-09 21:25   ` Justin Stitt

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