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

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Date:   Tue, 20 Nov 2018 18:23:23 +0800
From:   CK Hu <ck.hu@...iatek.com>
To:     Matthias Brugger <matthias.bgg@...il.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

Hi, Matthias:

On Tue, 2018-11-20 at 11:19 +0100, Matthias Brugger wrote:
> 
> 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?

Sounds good to me.

Regards,
CK

> Regards,
> Matthias