From: Jani Nikula <jani.nikula@linux.intel.com>
To: Lucas De Marchi <lucas.demarchi@intel.com>,
intel-gfx@lists.freedesktop.org
Subject: Re: [PATCH 3/3] drm/i915/bios: assume vbt is 4-byte aligned into oprom
Date: Fri, 29 Nov 2019 12:00:14 +0200 [thread overview]
Message-ID: <87o8wvkno1.fsf@intel.com> (raw)
In-Reply-To: <20191126225110.8127-4-lucas.demarchi@intel.com>
On Tue, 26 Nov 2019, Lucas De Marchi <lucas.demarchi@intel.com> wrote:
> The unaligned ioread32() will make us read byte by byte looking for the
> vbt. We could just as well have done a ioread8() + a shift and avoid the
> extra confusion on how we are looking for "$VBT".
>
> However when using ACPI it's guaranteed the VBT is 4-byte aligned
> per spec, so we can probably assume it here as well.
>
> v2: do not try to simplify the loop by eliminating the auxiliary counter
> (Jani and Ville)
>
> Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
> ---
> drivers/gpu/drm/i915/display/intel_bios.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_bios.c b/drivers/gpu/drm/i915/display/intel_bios.c
> index 56e566945e98..fec6752b1f56 100644
> --- a/drivers/gpu/drm/i915/display/intel_bios.c
> +++ b/drivers/gpu/drm/i915/display/intel_bios.c
> @@ -1909,7 +1909,7 @@ static struct vbt_header *oprom_get_vbt(struct drm_i915_private *dev_priv)
> return NULL;
>
> /* Scour memory looking for the VBT signature. */
> - for (i = 0; i + 4 < size; i++) {
> + for (i = 0; i + 4 < size; i += 4) {
> if (ioread32(oprom + i) != *((const u32 *)"$VBT"))
> continue;
--
Jani Nikula, Intel Open Source Graphics Center
_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/intel-gfx
WARNING: multiple messages have this Message-ID (diff)
From: Jani Nikula <jani.nikula@linux.intel.com>
To: Lucas De Marchi <lucas.demarchi@intel.com>,
intel-gfx@lists.freedesktop.org
Subject: Re: [Intel-gfx] [PATCH 3/3] drm/i915/bios: assume vbt is 4-byte aligned into oprom
Date: Fri, 29 Nov 2019 12:00:14 +0200 [thread overview]
Message-ID: <87o8wvkno1.fsf@intel.com> (raw)
Message-ID: <20191129100014.5Z5DsvJ6cypu1wPz3_kSm1ZWf-6m8ZhAOt2BvHYxoD4@z> (raw)
In-Reply-To: <20191126225110.8127-4-lucas.demarchi@intel.com>
On Tue, 26 Nov 2019, Lucas De Marchi <lucas.demarchi@intel.com> wrote:
> The unaligned ioread32() will make us read byte by byte looking for the
> vbt. We could just as well have done a ioread8() + a shift and avoid the
> extra confusion on how we are looking for "$VBT".
>
> However when using ACPI it's guaranteed the VBT is 4-byte aligned
> per spec, so we can probably assume it here as well.
>
> v2: do not try to simplify the loop by eliminating the auxiliary counter
> (Jani and Ville)
>
> Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
> ---
> drivers/gpu/drm/i915/display/intel_bios.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_bios.c b/drivers/gpu/drm/i915/display/intel_bios.c
> index 56e566945e98..fec6752b1f56 100644
> --- a/drivers/gpu/drm/i915/display/intel_bios.c
> +++ b/drivers/gpu/drm/i915/display/intel_bios.c
> @@ -1909,7 +1909,7 @@ static struct vbt_header *oprom_get_vbt(struct drm_i915_private *dev_priv)
> return NULL;
>
> /* Scour memory looking for the VBT signature. */
> - for (i = 0; i + 4 < size; i++) {
> + for (i = 0; i + 4 < size; i += 4) {
> if (ioread32(oprom + i) != *((const u32 *)"$VBT"))
> continue;
--
Jani Nikula, Intel Open Source Graphics Center
_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/intel-gfx
next prev parent reply other threads:[~2019-11-29 10:00 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-26 22:51 [PATCH 0/3] bios: dot not discard address space Lucas De Marchi
2019-11-26 22:51 ` [Intel-gfx] " Lucas De Marchi
2019-11-26 22:51 ` [PATCH 1/3] drm/i915/bios: do " Lucas De Marchi
2019-11-26 22:51 ` [Intel-gfx] " Lucas De Marchi
2019-11-26 22:51 ` [PATCH 2/3] drm/i915/bios: fold pci rom map/unmap into copy function Lucas De Marchi
2019-11-26 22:51 ` [Intel-gfx] " Lucas De Marchi
2019-11-26 22:51 ` [PATCH 3/3] drm/i915/bios: assume vbt is 4-byte aligned into oprom Lucas De Marchi
2019-11-26 22:51 ` [Intel-gfx] " Lucas De Marchi
2019-11-29 10:00 ` Jani Nikula [this message]
2019-11-29 10:00 ` Jani Nikula
2019-11-27 0:14 ` ✗ Fi.CI.BAT: failure for bios: dot not discard address space Patchwork
2019-11-27 0:14 ` [Intel-gfx] " Patchwork
2019-11-27 0:53 ` Lucas De Marchi
2019-11-27 0:53 ` [Intel-gfx] " Lucas De Marchi
2019-11-27 11:27 ` ✓ Fi.CI.BAT: success for bios: dot not discard address space (rev2) Patchwork
2019-11-27 11:27 ` [Intel-gfx] " Patchwork
2019-11-27 20:12 ` ✗ Fi.CI.IGT: failure " Patchwork
2019-11-27 20:12 ` [Intel-gfx] " Patchwork
2019-11-29 18:28 ` Lucas De Marchi
2019-11-29 18:28 ` [Intel-gfx] " Lucas De Marchi
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