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Message-ID: <CANqRtoTMf4TP2gcEuF4y5qdRz0fdf9-sebS=ymg+4zAGMj8dSA@mail.gmail.com>
Date: Fri, 20 Nov 2015 16:16:15 +0900
From: Magnus Damm <magnus.damm@...il.com>
To: Laurent Pinchart <laurent.pinchart@...asonboard.com>
Cc: SH-Linux <linux-sh@...r.kernel.org>,
Linus Walleij <linus.walleij@...aro.org>,
linux-kernel <linux-kernel@...r.kernel.org>,
Koji Matsuoka <koji.matsuoka.xm@...esas.com>,
linux-gpio <linux-gpio@...r.kernel.org>,
"Simon Horman [Horms]" <horms@...ge.net.au>, geert@...der.be
Subject: Re: [PATCH 00/04] pinctrl: sh-pfc: r8a7794: DU support
Hi Laurent,
On Fri, Nov 20, 2015 at 11:46 AM, Laurent Pinchart
<laurent.pinchart@...asonboard.com> wrote:
> Hi Magnus,
>
> Thank you for the patch.
>
> On Tuesday 17 November 2015 12:18:32 Magnus Damm wrote:
>> pinctrl: sh-pfc: r8a7794: DU support
>>
>> [PATCH 01/04] pinctrl: sh-pfc: r8a7794: Add DU pin groups
>> [PATCH 02/04] pinctrl: sh-pfc: r8a7794: Separate DU CDE and DISP
>> [PATCH 03/04] pinctrl: sh-pfc: r8a7794: Add missing dot clock signals
>> [PATCH 04/04] pinctrl: sh-pfc: r8a7794: Break out ODDF from sync
>>
>> These patches take the r8a7794 PFC DU support code from the BSP
>> and reworks it to fit the r8a7794 ALT board. Tested with the ALT
>> VGA port - by default PFC is not used however enabling PFC using
>> an incremental (yet to be posted) patch works well.
>>
>> It is worth noting that patch 2-4 modifies the pin groups. This
>> means that the upstream DT ABI for PFC DU will differ compared
>> to the unreviewed BSP code.
>>
>> In general it is not considered good practice to change the pin
>> groups and break compatibility since they are part of the DT ABI.
>>
>> For this particular case upstream never have had PFC DU support
>> for r8a7794, so treating the BSP bindings as experimental and
>> migrate away seems reasonable.
>
> If we start considering DT bindings that never went upstream as stable we'll
> have a big problem. I mean even bigger than the upstream DT bindings stability
> problem :-)
I'm not saying that local DT hacks should be considered stable, more
that it as usual makes sense to follow upstream first with proper DT
review process early on.
>> Signed-off-by: Magnus Damm <damm+renesas@...nsource.se>
>
> Wouldn't it make sense to merge the 4 patches together ?
Yeah, I guess so. My feeling is also that it would be good to verify
HDMI on ALT before commiting to DT bindings. Right now only one DU
channel is tested.
Cheers,
/ magnus
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