From: Dave Airlie <airlied@gmail.com>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Jerome Glisse <j.glisse@gmail.com>,
linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
linux-fbdev@vger.kernel.org
Subject: Re: [PATCH 3/7] drm: Update drm_addmap and drm_mmap to use PAT WC instead of MTRRs
Date: Tue, 07 May 2013 03:09:48 +0000 [thread overview]
Message-ID: <CAPM=9twx2VL2_Xo2-byhWcZ5csbYzyV18trEOzAqmHT8javGrg@mail.gmail.com> (raw)
In-Reply-To: <CALCETrXO7OVxjw5nJ+HrBP7yAoAXk14w1cMbWBC4ZdBmZ6-3JQ@mail.gmail.com>
>>
>> From memory, even on pat system we need mtrr for VRAM is PCI BAR. We
>> cover it with a write combine MTRR. The whole ioctl is use by some ddx
>> or maybe even directly the XServer to do this mtrr mess in userspace.
>
> Egads! So we have a _DRM_WRITE_COMBINING flag, which will continue to
> work fine, but almost nothing uses it.
>
> I'm amazed this stuff works in the current code, though. Apparently
> the memory type (WC or UC) of a drm mapping is determined by the mtrr
> the driver set, but if one part of the BAR is textures or the
> framebuffer and another part is an outgoing command ring, won't one of
> them end up with the wrong memory type?
Nobody sane puts the command ring in VRAM.
Dave.
next prev parent reply other threads:[~2013-05-07 3:09 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-05-03 23:00 [PATCH 0/7] Clean up write-combining MTRR addition Andy Lutomirski
2013-05-03 23:00 ` [PATCH 1/7] x86: Add mtrr_{add,del}_wc_if_needed Andy Lutomirski
2013-05-03 23:00 ` [PATCH 2/7] drm (ast,cirrus,mgag200,nouveau,savage,vmwgfx): Rework drm_mtrr_{add,del} Andy Lutomirski
2013-05-04 17:45 ` [PATCH 2/7] drm (ast, cirrus, mgag200, nouveau, savage, vmwgfx): Rework drm_mtrr_{add, del} Daniel Vetter
2013-05-04 17:48 ` Andy Lutomirski
2013-05-03 23:00 ` [PATCH 3/7] drm: Update drm_addmap and drm_mmap to use PAT WC instead of MTRRs Andy Lutomirski
2013-05-06 21:22 ` Andy Lutomirski
2013-05-06 23:04 ` Jerome Glisse
2013-05-06 23:39 ` Andy Lutomirski
2013-05-07 3:09 ` Dave Airlie [this message]
2013-05-07 14:08 ` Alex Deucher
2013-05-07 16:45 ` Andy Lutomirski
2013-05-03 23:00 ` [PATCH 4/7] drm: Use drm_mtrr_add_wc for the AGP aperture Andy Lutomirski
2013-05-03 23:00 ` [PATCH 5/7] i915: Use drm_mtrr_{add,del}_wc Andy Lutomirski
2013-05-03 23:00 ` [PATCH 6/7] radeon: Switch to drm_mtrr_add_wc and add a missing drm_mtrr_del_wc Andy Lutomirski
2013-05-03 23:00 ` [PATCH 7/7] uvesafb: Clean up MTRR code Andy Lutomirski
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