From: "Michel Dänzer" <michel@daenzer.net>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: xorg-driver-ati@lists.x.org,
Cedric Cano <ccano@interfaceconcept.com>,
dri-devel@lists.freedesktop.org
Subject: Re: [PATCH 3/6] drm/radeon: Writeback endian fixes
Date: Thu, 14 Jul 2011 17:19:24 +0200 [thread overview]
Message-ID: <1310656765.22333.10.camel@thor.local> (raw)
In-Reply-To: <1310538497.4968.93.camel@pasglop>
On Mit, 2011-07-13 at 16:28 +1000, Benjamin Herrenschmidt wrote:
> The writeback ring pointer and IH ring pointer are read using le32_to_cpu
> so we do not want the chip to byteswap them on big-endian.
>
> We still want to byteswap the ring itself and the IBs, so we don't touch
> that but we remove setting of the byteswap bits in CP_RB_RPTR_ADDR and
> IH_CNTL.
>
> In general, for things like that where we control all the accessors easily,
> we are better off doing the swap in SW rather than HW. Paradoxally, it does
> keep the code closer to x86 and avoid using poorly tested HW features.
Absolutely. Unfortunately, when I fixed the CP writeback code to use
le32_to_cpu(), I didn't realize the code for some GPU families was
already using HW swappers for this.
> I also changed the use of RADEON_ to R600_ in a couple of cases to be more
> consistent with the surrounding code.
That should probably be in a separate patch. Either way, though:
Reviewed-by: Michel Dänzer <michel@daenzer.net>
--
Earthling Michel Dänzer | http://www.amd.com
Libre software enthusiast | Debian, X and DRI developer
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next prev parent reply other threads:[~2011-07-14 15:19 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-07-13 6:28 [PATCH 3/6] drm/radeon: Writeback endian fixes Benjamin Herrenschmidt
2011-07-13 14:42 ` Alex Deucher
[not found] ` <CADnq5_M2v5CdVNxGqsTfKYT37=p2A5dQ3zcP9NkH42rOVBHDEQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2011-07-13 21:41 ` Benjamin Herrenschmidt
2011-07-14 2:24 ` Alex Deucher
2011-07-14 15:19 ` Michel Dänzer [this message]
2011-07-14 15:34 ` Benjamin Herrenschmidt
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