linux-kernel - Re: BOG: commit 89c7cb1608ac3 ("of/device: Update dma_range_map only when dev has valid dma-ranges") seems to break Pinephone display or LCDC

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Message-ID: <YB1f2kYMtHnM5ye1@aptenodytes>
Date:   Fri, 5 Feb 2021 16:10:18 +0100
From:   Paul Kocialkowski <paul.kocialkowski@...tlin.com>
To:     "H. Nikolaus Schaller" <hns@...delico.com>
Cc:     Robin Murphy <robin.murphy@....com>,
        Yong Wu <yong.wu@...iatek.com>, Rob Herring <robh@...nel.org>,
        Frank Rowand <frowand.list@...il.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        Discussions about the Letux Kernel 
        <letux-kernel@...nphoenux.org>
Subject: Re: BOG: commit 89c7cb1608ac3 ("of/device: Update dma_range_map only
 when dev has valid dma-ranges") seems to break Pinephone display or LCDC

Hey,

On Tue 02 Feb 21, 16:07, H. Nikolaus Schaller wrote:
> Hi Paul,
> 
> > Am 02.02.2021 um 14:42 schrieb Paul Kocialkowski <paul.kocialkowski@...tlin.com>:
> > 
> > Hi Nikolaus,
> > 
> > On Tue 02 Feb 21, 11:50, H. Nikolaus Schaller wrote:
> >> Hi Paul,
> >> 
> >>> Am 02.02.2021 um 10:56 schrieb Paul Kocialkowski <paul.kocialkowski@...tlin.com>:
> >>> 
> >>> Hi Nikolaus,
> >>> 
> >>> On Tue 02 Feb 21, 10:18, H. Nikolaus Schaller wrote:
> >>>> Hi,
> >>>> since v5.11-rc6 my Pinephone display shows some moiré pattern.
> >>>> 
> >>>> I did a bisect between v5.11-rc5 and v5.11-rc6 and it told me that
> >>>> the commit mentioned in the subject is the reason.
> >>>> 
> >>>> Reverting it makes the display work again and re-reverting fail again.
> >>>> 
> >>>> IMHO it seems as if the display DMA of the pinephone (allwinner suni-a54)
> >>>> got influenced and stopped to scan the framebuffer.
> >>>> 
> >>>> The only dma-ranges I could find are defined here:
> >>>> 
> >>>> 	arch/arm64/boot/dts/allwinner/sun50i-a64.dtsi
> >>>> 
> >>>> 	dma-ranges = <0x00000000 0x40000000 0xc0000000>;
> >>>> 
> >>>> but I can't tell if they are "valid" or not.
> >>>> 
> >>>> Any insights are welcome. And please direct to the right people/mailing lists
> >>>> if they are missing.
> >>> 
> >>> This may not be strictly the same thing, but is this patch in your tree:
> >>> https://patchwork.kernel.org/project/linux-arm-kernel/patch/20210115175831.1184260-2-paul.kocialkowski@bootlin.com/
> >>> 
> >>> If not, it's worth a try to add it.
> >> 
> >> No, it hasn't arrived in v5.11-rc6 (or linux-next) yet.
> >> 
> >> But it fixes the issue.
> > 
> > Great! The patch should already be on its way to the next RC.
> 
> Fine!
> 
> > 
> > And nice to see you're active on Pinephone as well!
> 
> I have a developer unit and the LetuxOS kernel already supports it a little. This is why I observed the issue with -rc6
> 
> > You might remember me from
> > the Replicant project, as I've worked a bit on the GTA04 :)
> 
> Sure, you are well remembered :)
> 
> I still have the dream to revitalize Replicant 4.2 for the GTA04 just for fun. I can already boot to Replicant touch screen with a v5.4 kernel. v5.10 fails when trying to spawn zygote...

Oh I see! I think Android has made some significant progress is its ability
to use mainline (4.2 was an early stage and I remember having to backport
patches to use some mainline features back then).

Maybe it would be easier with Replicant 6, but you'd have to go through the
device bringup phase again, which is never nice.

Cheers,

Paul

-- 
Paul Kocialkowski, Bootlin
Embedded Linux and kernel engineering
https://bootlin.com

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