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/[email protected]/ If not, it's worth a try to add it. If it is, it's worth doing a revert. My understanding is like DE2 does not need a particular DMA range and has DRAM starting at 0x40000000 (just like the CPU) but it will map DRAM in a loop before and after this address. I suspect the issue shows because the pinephone has 2 GiB RAM while for other boards with < 2 GiB RAM, removing 0x40000000 to the DMA addresses still points to the same location. So IMO the MBUS dma-ranges shouldn't apply to DE2. I think this is already the case in dt, but the mbus driver may add it if you don't have that patch. I think I have a few A64 boards around, but probably not with 2 GiB RAM. If adding the patch doesn't help, I'll try to make a few test. Cheers! Paul -- Paul Kocialkowski, Bootlin Embedded Linux and kernel engineering https://bootlin.com
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