[PATCH] drm/exynos: fix size_t format string

[PATCH] drm/exynos: fix size_t format string

[Arnd Bergmann]

From: Arnd Bergmann <arnd@arndb.de>

The exynos_gem->base.size argument is a size_t rather than an
unsigned long, so adapt the printk() format string accordingly:

In file included from drivers/gpu/drm/exynos/exynos_drm_gem.c:16:
drivers/gpu/drm/exynos/exynos_drm_gem.c: In function 'exynos_drm_alloc_buf':
drivers/gpu/drm/exynos/exynos_drm_gem.c:69:49: error: format '%lx' expects argument of type 'long unsigned int', but argument 6 has type 'size_t' {aka 'unsigned int'} [-Werror=format=]
   69 |         DRM_DEV_DEBUG_KMS(drm_dev_dma_dev(dev), "dma_addr(0x%lx), size(0x%lx)\n",
      |                                                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   70 |                         (unsigned long)exynos_gem->dma_addr, exynos_gem->base.size);
      |                                                              ~~~~~~~~~~~~~~~~~~~~~
      |                                                                              |
      |                                                                              size_t {aka unsigned int}

The dma_addr in the same line is already printed using a cast
to unsigned long, so change that similarly to use the correct
%pad format.

Fixes: 11e898373fba ("drm/exynos: Drop exynos_drm_gem.size field")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/gpu/drm/exynos/exynos_drm_gem.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/exynos/exynos_drm_gem.c b/drivers/gpu/drm/exynos/exynos_drm_gem.c
index 297a93b087cd..8e357f2beb9e 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_gem.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_gem.c
@@ -66,8 +66,8 @@ static int exynos_drm_alloc_buf(struct exynos_drm_gem *exynos_gem, bool kvmap)
 	if (kvmap)
 		exynos_gem->kvaddr = exynos_gem->cookie;
 
-	DRM_DEV_DEBUG_KMS(drm_dev_dma_dev(dev), "dma_addr(0x%lx), size(0x%lx)\n",
-			(unsigned long)exynos_gem->dma_addr, exynos_gem->base.size);
+	DRM_DEV_DEBUG_KMS(drm_dev_dma_dev(dev), "dma_addr(%pad), size(0x%zx)\n",
+			  &exynos_gem->dma_addr, exynos_gem->base.size);
 	return 0;
 }
 
@@ -80,8 +80,8 @@ static void exynos_drm_free_buf(struct exynos_drm_gem *exynos_gem)
 		return;
 	}
 
-	DRM_DEV_DEBUG_KMS(dev->dev, "dma_addr(0x%lx), size(0x%lx)\n",
-			(unsigned long)exynos_gem->dma_addr, exynos_gem->base.size);
+	DRM_DEV_DEBUG_KMS(dev->dev, "dma_addr(0x%pad), size(0x%zx)\n",
+			  &exynos_gem->dma_addr, exynos_gem->base.size);
 
 	dma_free_attrs(drm_dev_dma_dev(dev), exynos_gem->base.size, exynos_gem->cookie,
 			(dma_addr_t)exynos_gem->dma_addr,
-- 
2.39.5

Re: [PATCH] drm/exynos: fix size_t format string

[Chen-Yu Tsai]

On Wed, May 27, 2026 at 9:45 PM Arnd Bergmann <arnd@kernel.org> wrote:
>
> From: Arnd Bergmann <arnd@arndb.de>
>
> The exynos_gem->base.size argument is a size_t rather than an
> unsigned long, so adapt the printk() format string accordingly:
>
> In file included from drivers/gpu/drm/exynos/exynos_drm_gem.c:16:
> drivers/gpu/drm/exynos/exynos_drm_gem.c: In function 'exynos_drm_alloc_buf':
> drivers/gpu/drm/exynos/exynos_drm_gem.c:69:49: error: format '%lx' expects argument of type 'long unsigned int', but argument 6 has type 'size_t' {aka 'unsigned int'} [-Werror=format=]
>    69 |         DRM_DEV_DEBUG_KMS(drm_dev_dma_dev(dev), "dma_addr(0x%lx), size(0x%lx)\n",
>       |                                                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>    70 |                         (unsigned long)exynos_gem->dma_addr, exynos_gem->base.size);
>       |                                                              ~~~~~~~~~~~~~~~~~~~~~
>       |                                                                              |
>       |                                                                              size_t {aka unsigned int}
>
> The dma_addr in the same line is already printed using a cast
> to unsigned long, so change that similarly to use the correct
> %pad format.
>
> Fixes: 11e898373fba ("drm/exynos: Drop exynos_drm_gem.size field")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

I posted the same patch [1] one and a half months ago when the culprit
patch was queued up and I got a report about this from the bots.

Inki hasn't picked up my fix yet.

And it seems the exynos-drm-next stuff was only merged into drm-next
yesterday, now causing the warnings to pop up all over.

ChenYu

[1] https://lore.kernel.org/all/20260408064936.1342321-1-wenst@chromium.org/

> ---
>  drivers/gpu/drm/exynos/exynos_drm_gem.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/exynos/exynos_drm_gem.c b/drivers/gpu/drm/exynos/exynos_drm_gem.c
> index 297a93b087cd..8e357f2beb9e 100644
> --- a/drivers/gpu/drm/exynos/exynos_drm_gem.c
> +++ b/drivers/gpu/drm/exynos/exynos_drm_gem.c
> @@ -66,8 +66,8 @@ static int exynos_drm_alloc_buf(struct exynos_drm_gem *exynos_gem, bool kvmap)
>         if (kvmap)
>                 exynos_gem->kvaddr = exynos_gem->cookie;
>
> -       DRM_DEV_DEBUG_KMS(drm_dev_dma_dev(dev), "dma_addr(0x%lx), size(0x%lx)\n",
> -                       (unsigned long)exynos_gem->dma_addr, exynos_gem->base.size);
> +       DRM_DEV_DEBUG_KMS(drm_dev_dma_dev(dev), "dma_addr(%pad), size(0x%zx)\n",
> +                         &exynos_gem->dma_addr, exynos_gem->base.size);
>         return 0;
>  }
>
> @@ -80,8 +80,8 @@ static void exynos_drm_free_buf(struct exynos_drm_gem *exynos_gem)
>                 return;
>         }
>
> -       DRM_DEV_DEBUG_KMS(dev->dev, "dma_addr(0x%lx), size(0x%lx)\n",
> -                       (unsigned long)exynos_gem->dma_addr, exynos_gem->base.size);
> +       DRM_DEV_DEBUG_KMS(dev->dev, "dma_addr(0x%pad), size(0x%zx)\n",
> +                         &exynos_gem->dma_addr, exynos_gem->base.size);
>
>         dma_free_attrs(drm_dev_dma_dev(dev), exynos_gem->base.size, exynos_gem->cookie,
>                         (dma_addr_t)exynos_gem->dma_addr,
> --
> 2.39.5
>

Claude review: drm/exynos: fix size_t format string

[Claude Code Review Bot]

Patch Review

**Correctness of the format changes:**

The two format changes are correct:

1. `%lx` → `%zx` for `exynos_gem->base.size` (which is `size_t`): Correct. `%zx` is the proper portable format specifier for `size_t`.

2. `%lx` with `(unsigned long)` cast → `%pad` with `&` for `exynos_gem->dma_addr` (which is `dma_addr_t`): Correct. `%pad` is the kernel's recommended format for `dma_addr_t` and takes a pointer to the value.

**Minor inconsistency between the two hunks:**

In `exynos_drm_alloc_buf`, the format string is:
```c
"dma_addr(%pad), size(0x%zx)\n"
```

But in `exynos_drm_free_buf`, the format string is:
```c
"dma_addr(0x%pad), size(0x%zx)\n"
```

The `0x` prefix before `%pad` in the second hunk is incorrect — `%pad` already includes the `0x` prefix in its output (it uses `phys_addr_t` formatting which prepends `0x`). This would result in output like `dma_addr(0x0x12345678)` in the free path. The first hunk correctly omits the `0x` prefix.

Looking at the diff more closely:

```
-	DRM_DEV_DEBUG_KMS(dev->dev, "dma_addr(0x%lx), size(0x%lx)\n",
-			(unsigned long)exynos_gem->dma_addr, exynos_gem->base.size);
+	DRM_DEV_DEBUG_KMS(dev->dev, "dma_addr(0x%pad), size(0x%zx)\n",
+			  &exynos_gem->dma_addr, exynos_gem->base.size);
```

The `0x` was left in front of `%pad` in the second hunk but correctly removed in the first hunk. This should be `"dma_addr(%pad), size(0x%zx)\n"` to be consistent and avoid the double-prefix.

**Alignment fix:** The patch also adjusts continuation line alignment from tabs to spaces to match the opening parenthesis, which is a nice cleanup.

**Recommendation:** The `0x%pad` in the second hunk should be changed to just `%pad` to match the first hunk and avoid doubled `0x` output. Otherwise the patch is correct and should be applied.

---
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Claude review: drm/exynos: fix size_t format string

[Claude Code Review Bot]

Overall Series Review

Subject: drm/exynos: fix size_t format string
Author: Arnd Bergmann <arnd@kernel.org>
Patches: 2
Reviewed: 2026-05-28T12:08:08.345241

---

This is a single-patch fix from Arnd Bergmann addressing a `-Werror=format` build warning/error in the Exynos DRM GEM code. The `exynos_gem->base.size` field is `size_t`, which is `unsigned int` on 32-bit ARM, but was being printed with `%lx` (expects `unsigned long`). The fix changes the format to `%zx` for size and `%pad` for the DMA address. The patch is correct and straightforward, though there is one minor inconsistency worth noting.

**Verdict: Looks good overall, one minor nit.**

---
Generated by Claude Code Patch Reviewer