linux-kernel - Re: [PATCH v5 05/12] drm: mediatek: Omit warning on probe defers

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Date:   Tue, 20 Nov 2018 11:19:00 +0100
From:   Matthias Brugger <matthias.bgg@...il.com>
To:     CK Hu <ck.hu@...iatek.com>
Cc:     matthias.bgg@...nel.org, robh+dt@...nel.org, mark.rutland@....com,
        p.zabel@...gutronix.de, airlied@...ux.ie, mturquette@...libre.com,
        sboyd@...eaurora.org, ulrich.hecht+renesas@...il.com,
        laurent.pinchart@...asonboard.com, sean.wang@...iatek.com,
        sean.wang@...nel.org, rdunlap@...radead.org, wens@...e.org,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-clk@...r.kernel.org,
        devicetree@...r.kernel.org, Matthias Brugger <mbrugger@...e.com>
Subject: Re: [PATCH v5 05/12] drm: mediatek: Omit warning on probe defers



On 20/11/2018 05:05, CK Hu wrote:
> Hi, Matthias:
> 
> On Mon, 2018-11-19 at 10:26 +0100, Matthias Brugger wrote:
>>
>> On 19/11/2018 06:38, CK Hu wrote:
>>> Hi, Matthias:
>>>
>>> On Fri, 2018-11-16 at 13:54 +0100, matthias.bgg@...nel.org wrote:
>>>> From: Matthias Brugger <mbrugger@...e.com>
>>>>
>>>> It can happen that the mmsys clock drivers aren't probed before the
>>>> platform driver gets invoked. The platform driver used to print a warning
>>>> that the driver failed to get the clocks. Omit this error on
>>>> the defered probe path.
>>>
>>> This patch looks good to me, but you have not modified the sub driver in
>>> HDMI path. We could let HDMI path print the warning and someone send
>>> another patch later, or you modify for HDMI path in this patch.
>>
>> Sure, I'll add this in v6. After inspecting the code, I think we will need to
>> also check for not initialized clocks in mtk_mdp_comp_init, as the driver for
>> now does not even check if the clocks are present. What do you think?
> 
> Yes, we do really need to consider mdp driver because mmsys clock
> include mdp clock. You remind me that mmsys control 4 major function:
> drm routing, drm clock, mdp routing, and mdp clock. Your design let the
> mmsys device as drm device (control drm routing) and create a sub device
> as clock device (control drm clock, mdp clock). If one day mdp device
> (may need control drm routing) need to control the register of mdp
> routing, would mdp device be a sub device? Or we need not to consider
> this because it need not to access mmsys register now?
> 

I think we should for now concentrate to fix the clock probing issue. If in the
future we will need to access drm routing from the mdp device, we can have a
look into this.

Sounds good?
Regards,
Matthias