Hi Paul, > Am 02.02.2021 um 10:56 schrieb Paul Kocialkowski > <paul.kocialkow...@bootlin.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.kocialkow...@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 and many thanks, Nikolaus > 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