From: Thomas Hellstrom <thomas@shipmail.org>
To: april <aapril03@gmail.com>
Cc: dri-devel@lists.freedesktop.org
Subject: Re: seems ttm_bo_handle_move_mem not flush cache, if BO move SYS->VRAM?
Date: Wed, 01 Dec 2010 17:28:26 +0100 [thread overview]
Message-ID: <4CF677AA.4090207@shipmail.org> (raw)
In-Reply-To: <AANLkTinFOdC6uS+a8nua=pEu_mfa9h392UK_Qg6u+5gR@mail.gmail.com>
On 12/01/2010 04:58 AM, april wrote:
> hi all:
>
> I have a question:
>
> If a BO in VRAM (WC) evict to SYS memory(may be cached), and user
> process still can access it event it is in SYS memory (may be cached)
> .
> when this BO volidate to VRAM, It seems "ttm_bo_handle_move_mem" not
> flush cache (If evict to SYS memory with cached).
>
> But flush cache is needed, If driver use DMA to handle BO
> move(SYS->VRAM), should "ttm_bo_handle_move_mem" handle this? or
> driver do it in "driver->move_notify" before "driver->move" called?
>
>
April, in order to understand your proble, Can you be a bit more
specific about.
1) Which cache should be flushed? Cpu cache or GPU cache.
2) Why should it be flushed? For CPU caches, TTM only flushes when
transitioning the same page from cached to write-combined. If you use
DMA from system memory to VRAM, and need to flush the system pages
before performing the DMA operation, that should be done in the driver
move function.
/Thomas
> Thanks
> _______________________________________________
> dri-devel mailing list
> dri-devel@lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/dri-devel
>
next prev parent reply other threads:[~2010-12-01 16:28 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-12-01 3:58 seems ttm_bo_handle_move_mem not flush cache, if BO move SYS->VRAM? april
2010-12-01 14:34 ` Jerome Glisse
2010-12-01 16:28 ` Thomas Hellstrom [this message]
2010-12-02 2:49 ` april
2010-12-02 7:35 ` Thomas Hellstrom
2010-12-03 2:25 ` Jerome Glisse
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