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From: Arun R Murthy <arun.r.murthy@intel.com>
To: "ville.syrjala@linux.intel.com" <ville.syrjala@linux.intel.com>,
	"intel-gfx@lists.freedesktop.org"
	<intel-gfx@lists.freedesktop.org>
Subject: Re: [PATCH 2/3] drm/i915: Align DSPSURF to 128k on VLV/CHV
Date: Fri, 12 Jun 2015 10:17:00 +0530	[thread overview]
Message-ID: <557A6444.50604@intel.com> (raw)
In-Reply-To: <1434029476-958-2-git-send-email-ville.syrjala@linux.intel.com>


On Thursday 11 June 2015 07:01 PM, ville.syrjala@linux.intel.com wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
>
> VLV/CHV have problems with 4k aligned linear scanout buffers. The VLV
> docs got updated at some point to say that we need to align them to
> 128k, just like we do on gen4.
>
> So far I've seen the problem manifest when the stride is an odd multiple
> of 512 bytes, and the surface address meets the following pattern
> '(addr & 0xf000) == 0x1000' (also == 0x2000 is problematic on VLV). The
> result is a starcase effect (so some pages get dropped maybe?), with a
> few pages here and there clearly getting scannout out at the wrong position.
>
> I've not actually been able to reproduce this problem on gen4, so it's
> not clear of the issue is any way related to the 128k restrictions
> supposedly inherited from gen4. But let's hope the 128k alignment is
> sufficient to hide it all.
>
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Arun R Murthy <arun.r.murthy@intel.com>

Thanks and Regards,
Arun R Murthy
-------------------

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  parent reply	other threads:[~2015-06-12  4:47 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-06-11 13:31 [PATCH 1/3] drm/i915: Actually respect DSPSURF alignment restrictions ville.syrjala
2015-06-11 13:31 ` [PATCH 2/3] drm/i915: Align DSPSURF to 128k on VLV/CHV ville.syrjala
2015-06-12  0:46   ` Clint Taylor
2015-06-12  4:47   ` Arun R Murthy [this message]
2015-06-11 13:31 ` [PATCH 3/3] drm/i915: Drop the 64k linear scanout alignment on gen2/3 ville.syrjala
2015-06-11 13:52   ` Chris Wilson
2015-06-14 23:18   ` shuang.he
2015-06-11 13:51 ` [PATCH 1/3] drm/i915: Actually respect DSPSURF alignment restrictions Chris Wilson
2015-06-12 10:50   ` Ville Syrjälä
2015-06-15 16:04     ` Daniel Vetter

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