2021-09-27 12:22:18

by Arnd Bergmann

Subject: [PATCH] drm/amdgpu: fix clang out-of-range warning

From: Arnd Bergmann <[email protected]>

clang-14 points out that comparing an 'unsigned int' against a large
64-bit constantn is pointless:

drivers/gpu/drm/amd/amdgpu/amdgpu_device.c:1206:18: error: result of comparison of constant 4294967296 with expression of type 'resource_size_t' (aka 'unsigned int') is always false [-Werror,-Wtautological-constant-out-of-range-compare]
res->start > 0x100000000ull)

Rephrase the comparison using the upper_32_bits() macro, which should
keep it legible while avoiding the warning.

Fixes: 31b8adab3247 ("drm/amdgpu: require a root bus window above 4GB for BAR resize")
Signed-off-by: Arnd Bergmann <[email protected]>
---
drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
index ab3794c42d36..741a55031ca1 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
@@ -1203,7 +1203,7 @@ int amdgpu_device_resize_fb_bar(struct amdgpu_device *adev)

pci_bus_for_each_resource(root, res, i) {
if (res && res->flags & (IORESOURCE_MEM | IORESOURCE_MEM_64) &&
- res->start > 0x100000000ull)
+ upper_32_bits(res->start) != 0)
break;
}

--
2.29.2

2021-09-27 12:27:36

by Christian König

Subject: Re: [PATCH] drm/amdgpu: fix clang out-of-range warning

In general that change looks good. But what configuration is that?

Background is that it doesn't make much sense to compile the amdgpu
driver on systems where resource_size_t is only 32bit.

Christian.

Am 27.09.21 um 14:19 schrieb Arnd Bergmann:
> From: Arnd Bergmann <[email protected]>
>
> clang-14 points out that comparing an 'unsigned int' against a large
> 64-bit constantn is pointless:
>
> drivers/gpu/drm/amd/amdgpu/amdgpu_device.c:1206:18: error: result of comparison of constant 4294967296 with expression of type 'resource_size_t' (aka 'unsigned int') is always false [-Werror,-Wtautological-constant-out-of-range-compare]
> res->start > 0x100000000ull)
>
> Rephrase the comparison using the upper_32_bits() macro, which should
> keep it legible while avoiding the warning.
>
> Fixes: 31b8adab3247 ("drm/amdgpu: require a root bus window above 4GB for BAR resize")
> Signed-off-by: Arnd Bergmann <[email protected]>
> ---
> drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> index ab3794c42d36..741a55031ca1 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> @@ -1203,7 +1203,7 @@ int amdgpu_device_resize_fb_bar(struct amdgpu_device *adev)
>
> pci_bus_for_each_resource(root, res, i) {
> if (res && res->flags & (IORESOURCE_MEM | IORESOURCE_MEM_64) &&
> - res->start > 0x100000000ull)
> + upper_32_bits(res->start) != 0)
> break;
> }
>