linux-kernel - Re: [PATCH v2 5/7] drm/ltdc: Use the panel-bridge helper.

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Message-ID: <536995e1-f805-bbec-c17c-ba318e5783c1@st.com>
Date:   Thu, 1 Jun 2017 09:53:27 +0000
From:   Philippe CORNU <philippe.cornu@...com>
To:     Archit Taneja <architt@...eaurora.org>,
        Boris Brezillon <boris.brezillon@...e-electrons.com>
CC:     Eric Anholt <eric@...olt.net>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        Andrzej Hajda <a.hajda@...sung.com>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        CK Hu <ck.hu@...iatek.com>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Yannick FERTRE <yannick.fertre@...com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 5/7] drm/ltdc: Use the panel-bridge helper.



On 05/31/2017 10:35 AM, Archit Taneja wrote:
> 
> 
> On 05/31/2017 01:37 PM, Boris Brezillon wrote:
>> Hi Archit,
>>
>> Le Wed, 31 May 2017 13:31:16 +0530,
>> Archit Taneja <architt@...eaurora.org> a écrit :
>>
>>> Hi Boris,
>>>
>>> On 05/31/2017 11:56 AM, Boris Brezillon wrote:
>>>> Hi Philippe,
>>>>
>>>> Le Tue, 30 May 2017 16:55:42 +0000,
>>>> Philippe CORNU <philippe.cornu@...com> a écrit :
>>>>
>>>>> Hi Eric,
>>>>>
>>>>> I took your patch for the panel-bridge and it works perfectly in both
>>>>> DPI mode (panel RGB //) and DSI mode (bridge dw mipi dsi), bravo :-)
>>>>
>>>> I still don't understand how it can work without a call to
>>>> drm_bridge_attach() (which is used to link the RGB encoder to the DPI
>>>> connector). I'm probably missing something obvious. Maybe someone can
>>>> point it out :-).
>>>
>>> I think the expectation is that there will be a follow-up patch that
>>> would add bridge support. Philippe had posted a patch for adding bridges
>>> to ltdc before:
>>>
>>> https://patchwork.kernel.org/patch/9724835/
>>>
>>> He can now redo his patch over Eric's panel-bridge patch-set.
>>
>> But by doing that you're breaking bisectability, or is it working when
>> applying only Eric's patchset?
>>
>> If applying this patch breaks the driver, why not applying it after
>> bridge support has been added to this driver?
> 
> Yeah, it would break the driver. Philippe can create a patch that adds
> bridge support using the panel-bridge glue layer using Eric's patch as a
> reference. In the end, there should only be a single patch.
> 
> Thanks,
> Archit
> 
>>
>> Regards,
>>
>> Boris
>>
> 

Hi Boris & Archit,

Sorry, I should have been clearer about what I did. Let me explain more 
below:

1 - I applied Eric's patch named "drm/bridge: Refactor out the panel 
wrapper from the lvds-encoder bridge" (https://lkml.org/lkml/2017/5/11/784)

2 - I did a patch on ltdc.c combining Eric's patch named "drm/ltdc: Use 
the panel-bridge helper" (https://lkml.org/lkml/2017/5/11/783) and my 
own preamble patch for STM32 DSI named "drm/stm: ltdc: Add bridge 
support" (https://patchwork.kernel.org/patch/9738427/)

And tests are successful in both DPI mode (panel RGB //) and DSI mode 
(bridge dw mipi dsi).

As suggested in the last Archit's email, there will be a single patch 
that will add bridge support to ltdc.c and I will send it in the "STM32 
DSI HOST" v3 version, if you all agree of course :)

Many thanks for all your great comments,
Philippe