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Message-ID: <cde2ba78716ae4903f9893f018796c79554bb168.camel@linux.intel.com>
Subject: Re: [PATCH] xe: avoid using writeq() on 32-bit
From: Thomas =?ISO-8859-1?Q?Hellstr=F6m?= <thomas.hellstrom@linux.intel.com>
To: Arnd Bergmann <arnd@kernel.org>, Lucas De Marchi
 <lucas.demarchi@intel.com>,  Oded Gabbay <ogabbay@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>, Maarten Lankhorst
 <maarten.lankhorst@linux.intel.com>, Maxime Ripard <mripard@kernel.org>, 
 Thomas Zimmermann <tzimmermann@suse.de>, David Airlie <airlied@gmail.com>,
 Daniel Vetter <daniel@ffwll.ch>, Rodrigo Vivi <rodrigo.vivi@intel.com>,
 Matt Roper <matthew.d.roper@intel.com>, Matthew Auld
 <matthew.auld@intel.com>, Matthew Brost <matthew.brost@intel.com>, Michal
 Wajdeczko <michal.wajdeczko@intel.com>, intel-xe@lists.freedesktop.org, 
 dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org
Date: Wed, 28 Feb 2024 15:44:14 +0100
In-Reply-To: <20240228122746.3091608-1-arnd@kernel.org>
References: <20240228122746.3091608-1-arnd@kernel.org>
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Hi, Arnd,

On Wed, 2024-02-28 at 13:27 +0100, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
>=20
> 32-bit kernels do not provide a writeq(), failing the build:
>=20
> drivers/gpu/drm/xe/xe_ggtt.c:78:2: error: use of undeclared
> identifier 'writeq'
> =C2=A0=C2=A0 78 |=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 writeq(=
pte, &ggtt->gsm[addr >> XE_PTE_SHIFT]);
>=20
> 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.
>=20
> 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.
>=20
> Fixes: 237412e45390 ("drm/xe: Enable 32bits build")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

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=3D130347&rev=3D1

/Thomas


> ---
> =C2=A0drivers/gpu/drm/xe/xe_ggtt.c | 1 +
> =C2=A01 file changed, 1 insertion(+)
>=20
> 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 @@
> =C2=A0#include "xe_ggtt.h"
> =C2=A0
> =C2=A0#include <linux/sizes.h>
> +#include <linux/io-64-nonatomic-lo-hi.h>
> =C2=A0
> =C2=A0#include <drm/drm_managed.h>
> =C2=A0#include <drm/i915_drm.h>