Re: [PATCH 00/04] pinctrl: sh-pfc: r8a7794: DU support

Magnus Damm
2015-11-20T07:16:18Z

Hi Laurent,

On Fri, Nov 20, 2015 at 11:46 AM, Laurent Pinchart
<laurent.pinchart@ideasonboard.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@opensource.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