linux-kernel - 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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Date:   Tue, 2 Feb 2021 10:18:02 +0100
From:   "H. Nikolaus Schaller" <hns@...delico.com>
To:     Robin Murphy <robin.murphy@....com>,
        Yong Wu <yong.wu@...iatek.com>,
        Paul Kocialkowski <paul.kocialkowski@...tlin.com>,
        Rob Herring <robh@...nel.org>
Cc:     Frank Rowand <frowand.list@...il.com>,
        Rob Herring <robh@...nel.org>,
        Robin Murphy <robin.murphy@....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: BOG: commit 89c7cb1608ac3 ("of/device: Update dma_range_map only when dev has valid dma-ranges") seems to break Pinephone display or LCDC

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.

BR and thanks,
Nikolaus Schaller