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From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Takashi Iwai <tiwai@suse.de>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>,
	Jean-Christophe Plagniol-Villard <plagnioj@jcrosoft.com>,
	Cedric Le Goater <clg@fr.ibm.com>,
	linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] offb: Fix little-endian support
Date: Mon, 16 Jun 2014 23:54:07 +0000	[thread overview]
Message-ID: <1402962847.7661.82.camel@pasglop> (raw)
In-Reply-To: <1402904135.7661.34.camel@pasglop>

On Mon, 2014-06-16 at 17:35 +1000, Benjamin Herrenschmidt wrote:

> I somewhat doubt that this (and 5:5:5) actually work, do they ? the
> green gets split into two separate fields, which we can't express
> properly here...

So the conclusion of further investigation is:

 - The right fix is to fix qemu to flip endian

 - There's an open discussion as to whether qemu could do it
automatically when the guest endian changes on powerpc as a quick fix,
the long run approach is to have a register to control it, I'm working
on it. offb can then "learn" to flick it like it does the palette hack
today.

 - If we want to ever support foreign endian offb with X, we need to do
things a bit differently based on the foreign endian bit that is already
there.

 - We must revert the existing cmap swap patch from the kernel, it's
broken and will break things when we fix qemu (and breaks with real HW
in LE mode). I've sent a revert request to Linus and CC'ed stable.

Cheers,
Ben.



WARNING: multiple messages have this Message-ID (diff)
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Takashi Iwai <tiwai@suse.de>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>,
	Jean-Christophe Plagniol-Villard <plagnioj@jcrosoft.com>,
	Cedric Le Goater <clg@fr.ibm.com>,
	linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] offb: Fix little-endian support
Date: Tue, 17 Jun 2014 09:54:07 +1000	[thread overview]
Message-ID: <1402962847.7661.82.camel@pasglop> (raw)
In-Reply-To: <1402904135.7661.34.camel@pasglop>

On Mon, 2014-06-16 at 17:35 +1000, Benjamin Herrenschmidt wrote:

> I somewhat doubt that this (and 5:5:5) actually work, do they ? the
> green gets split into two separate fields, which we can't express
> properly here...

So the conclusion of further investigation is:

 - The right fix is to fix qemu to flip endian

 - There's an open discussion as to whether qemu could do it
automatically when the guest endian changes on powerpc as a quick fix,
the long run approach is to have a register to control it, I'm working
on it. offb can then "learn" to flick it like it does the palette hack
today.

 - If we want to ever support foreign endian offb with X, we need to do
things a bit differently based on the foreign endian bit that is already
there.

 - We must revert the existing cmap swap patch from the kernel, it's
broken and will break things when we fix qemu (and breaks with real HW
in LE mode). I've sent a revert request to Linus and CC'ed stable.

Cheers,
Ben.



  reply	other threads:[~2014-06-16 23:54 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-05-14 13:21 [PATCH] offb: Fix little-endian support Takashi Iwai
2014-05-14 13:21 ` Takashi Iwai
2014-05-14 14:01 ` Cedric Le Goater
2014-05-14 14:01   ` Cedric Le Goater
2014-05-14 14:24   ` Takashi Iwai
2014-05-14 14:24     ` Takashi Iwai
2014-05-14 17:04     ` Cedric Le Goater
2014-05-14 17:04       ` Cedric Le Goater
2014-05-14 17:57       ` Takashi Iwai
2014-05-14 17:57         ` Takashi Iwai
2014-06-16  7:23         ` Benjamin Herrenschmidt
2014-06-16  7:23           ` Benjamin Herrenschmidt
2014-06-16  7:32         ` Benjamin Herrenschmidt
2014-06-16  7:32           ` Benjamin Herrenschmidt
2014-05-14 16:56   ` Geert Uytterhoeven
2014-05-14 16:56     ` Geert Uytterhoeven
2014-06-16  7:35 ` Benjamin Herrenschmidt
2014-06-16  7:35   ` Benjamin Herrenschmidt
2014-06-16 23:54   ` Benjamin Herrenschmidt [this message]
2014-06-16 23:54     ` Benjamin Herrenschmidt
2014-06-17 10:01     ` Takashi Iwai
2014-06-17 10:01       ` Takashi Iwai

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