2024-02-28 12:28:28

by Arnd Bergmann

Subject: [PATCH] xe: avoid using writeq() on 32-bit

From: Arnd Bergmann <[email protected]>

32-bit kernels do not provide a writeq(), failing the build:

drivers/gpu/drm/xe/xe_ggtt.c:78:2: error: use of undeclared identifier 'writeq'
78 | writeq(pte, &ggtt->gsm[addr >> XE_PTE_SHIFT]);

Using lo_hi_writeq() instead will write the lower 32 bits to the address
before writing the upper 32 bits to the following word, which is likely
the correct replacement to do on 32-bit targets.

Include the linux/io-64-nonatomic-lo-hi.h header to automatically pick
the regular writeq() on 64-bit machines but fall back to lo_hi_writeq()
on 32-bit ones.

Fixes: 237412e45390 ("drm/xe: Enable 32bits build")
Signed-off-by: Arnd Bergmann <[email protected]>
---
drivers/gpu/drm/xe/xe_ggtt.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/xe/xe_ggtt.c b/drivers/gpu/drm/xe/xe_ggtt.c
index 5d46958e3144..1ffcc63ca86d 100644
--- a/drivers/gpu/drm/xe/xe_ggtt.c
+++ b/drivers/gpu/drm/xe/xe_ggtt.c
@@ -6,6 +6,7 @@
#include "xe_ggtt.h"

#include <linux/sizes.h>
+#include <linux/io-64-nonatomic-lo-hi.h>

#include <drm/drm_managed.h>
#include <drm/i915_drm.h>
--
2.39.2

2024-02-28 14:45:50

by Thomas Hellström

Subject: Re: [PATCH] xe: avoid using writeq() on 32-bit

Hi, Arnd,

On Wed, 2024-02-28 at 13:27 +0100, Arnd Bergmann wrote:
> From: Arnd Bergmann <[email protected]>
>
> 32-bit kernels do not provide a writeq(), failing the build:
>
> drivers/gpu/drm/xe/xe_ggtt.c:78:2: error: use of undeclared
> identifier 'writeq'
>    78 |         writeq(pte, &ggtt->gsm[addr >> XE_PTE_SHIFT]);
>
> Using lo_hi_writeq() instead will write the lower 32 bits to the
> address
> before writing the upper 32 bits to the following word, which is
> likely
> the correct replacement to do on 32-bit targets.
>
> Include the linux/io-64-nonatomic-lo-hi.h header to automatically
> pick
> the regular writeq() on 64-bit machines but fall back to
> lo_hi_writeq()
> on 32-bit ones.
>
> Fixes: 237412e45390 ("drm/xe: Enable 32bits build")
> Signed-off-by: Arnd Bergmann <[email protected]>

Thanks for the patch.
We have a patch already on the list pending review comments that fixes
this.

https://patchwork.freedesktop.org/patch/579781/?series=130347&rev=1

/Thomas


> ---
>  drivers/gpu/drm/xe/xe_ggtt.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/drivers/gpu/drm/xe/xe_ggtt.c
> b/drivers/gpu/drm/xe/xe_ggtt.c
> index 5d46958e3144..1ffcc63ca86d 100644
> --- a/drivers/gpu/drm/xe/xe_ggtt.c
> +++ b/drivers/gpu/drm/xe/xe_ggtt.c
> @@ -6,6 +6,7 @@
>  #include "xe_ggtt.h"
>  
>  #include <linux/sizes.h>
> +#include <linux/io-64-nonatomic-lo-hi.h>
>  
>  #include <drm/drm_managed.h>
>  #include <drm/i915_drm.h>