From: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
To: Rodrigo Vivi <rodrigo.vivi@intel.com>, intel-gfx@lists.freedesktop.org
Subject: Re: [PATCH] drm/i915/cnl: Avoid ioremap_wc on Cannonlake as well.
Date: Wed, 30 Aug 2017 14:13:29 +0300 [thread overview]
Message-ID: <1504091609.8378.7.camel@linux.intel.com> (raw)
In-Reply-To: <20170829230907.21363-1-rodrigo.vivi@intel.com>
On Tue, 2017-08-29 at 16:09 -0700, Rodrigo Vivi wrote:
> Driver’s CPU access to GTT is via the GTTMMADR BAR.
>
> The current HW implementation of that BAR is to only
> support <= DW (and maybe QW) writes—not 16/32/64B writes
> that could occur with WC and/or SSE/AVX moves.
>
> GTTMMADR must be marked uncacheable (UC).
> Accesses to GTTMMADR(GTT), must be 64 bits or less (ie. 1 GTT entry).
>
> v2: Get clarification on the reasons and spec is getting
> updated to reflect it now.
>
> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
> Suggested-by: Ben Widawsky <benjamin.widawsky@intel.com>
> Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Rodrigo, can you double-check how this interacts with the patch from
Zhi that adds the WB flag to PPAT_CACHE_INDEX on CNL.
If that doesn't help with the problem, this is;
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Regards, Joonas
--
Joonas Lahtinen
Open Source Technology Center
Intel Corporation
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next prev parent reply other threads:[~2017-08-30 11:13 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-11 23:39 [PATCH] drm/i915/cnl: Avoid ioremap_wc on Cannonlake as well Rodrigo Vivi
2017-08-12 0:11 ` ✓ Fi.CI.BAT: success for " Patchwork
2017-08-12 0:36 ` [PATCH] " Rodrigo Vivi
2017-08-14 12:13 ` Joonas Lahtinen
2017-08-14 17:24 ` Vivi, Rodrigo
2017-08-29 23:09 ` Rodrigo Vivi
2017-08-30 11:13 ` Joonas Lahtinen [this message]
2017-08-30 11:26 ` Chris Wilson
2017-08-30 11:38 ` Joonas Lahtinen
2017-08-30 17:58 ` Vivi, Rodrigo
2017-08-31 8:27 ` Joonas Lahtinen
2017-08-31 16:45 ` Vivi, Rodrigo
2017-08-30 0:16 ` ✓ Fi.CI.BAT: success for drm/i915/cnl: Avoid ioremap_wc on Cannonlake as well. (rev2) Patchwork
2017-08-30 4:33 ` ✗ Fi.CI.IGT: warning " Patchwork
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