On 12/09/2019 21:32, Stefan Wahren wrote: > > Am 12.09.19 um 19:18 schrieb Matthias Brugger: >> >> On 10/09/2019 11:27, Matthias Brugger wrote: >>> >>> On 09/09/2019 21:33, Stefan Wahren wrote: >>>> Hi Nicolas, >>>> >>>> Am 09.09.19 um 11:58 schrieb Nicolas Saenz Julienne: >>>>> Hi all, >>>>> this series attempts to address some issues we found while bringing up >>>>> the new Raspberry Pi 4 in arm64 and it's intended to serve as a follow >>>>> up of these discussions: >>>>> v4: https://lkml.org/lkml/2019/9/6/352 >>>>> v3: https://lkml.org/lkml/2019/9/2/589 >>>>> v2: https://lkml.org/lkml/2019/8/20/767 >>>>> v1: https://lkml.org/lkml/2019/7/31/922 >>>>> RFC: https://lkml.org/lkml/2019/7/17/476 >>>>> >>>>> The new Raspberry Pi 4 has up to 4GB of memory but most peripherals can >>>>> only address the first GB: their DMA address range is >>>>> 0xc0000000-0xfc000000 which is aliased to the first GB of physical >>>>> memory 0x00000000-0x3c000000. Note that only some peripherals have these >>>>> limitations: the PCIe, V3D, GENET, and 40-bit DMA channels have a wider >>>>> view of the address space by virtue of being hooked up trough a second >>>>> interconnect. >>>>> >>>>> Part of this is solved on arm32 by setting up the machine specific >>>>> '.dma_zone_size = SZ_1G', which takes care of reserving the coherent >>>>> memory area at the right spot. That said no buffer bouncing (needed for >>>>> dma streaming) is available at the moment, but that's a story for >>>>> another series. >>>>> >>>>> Unfortunately there is no such thing as 'dma_zone_size' in arm64. Only >>>>> ZONE_DMA32 is created which is interpreted by dma-direct and the arm64 >>>>> arch code as if all peripherals where be able to address the first 4GB >>>>> of memory. >>>>> >>>>> In the light of this, the series implements the following changes: >>>>> >>>>> - Create both DMA zones in arm64, ZONE_DMA will contain the first 1G >>>>> area and ZONE_DMA32 the rest of the 32 bit addressable memory. So far >>>>> the RPi4 is the only arm64 device with such DMA addressing limitations >>>>> so this hardcoded solution was deemed preferable. >>>>> >>>>> - Properly set ARCH_ZONE_DMA_BITS. >>>>> >>>>> - Reserve the CMA area in a place suitable for all peripherals. >>>>> >>>>> This series has been tested on multiple devices both by checking the >>>>> zones setup matches the expectations and by double-checking physical >>>>> addresses on pages allocated on the three relevant areas GFP_DMA, >>>>> GFP_DMA32, GFP_KERNEL: >>>>> >>>>> - On an RPi4 with variations on the ram memory size. But also forcing >>>>> the situation where all three memory zones are nonempty by setting a 3G >>>>> ZONE_DMA32 ceiling on a 4G setup. Both with and without NUMA support. >>>>> >>>> i like to test this series on Raspberry Pi 4 and i have some questions >>>> to get arm64 running: >>>> >>>> Do you use U-Boot? Which tree? >>> If you want to use U-Boot, try v2019.10-rc4, it should have everything you need >>> to boot your kernel. >>> >> Ok, here is a thing. In the linux kernel we now use bcm2711 as SoC name, but the >> RPi4 devicetree provided by the FW uses mostly bcm2838. > > Do you mean the DTB provided at runtime? > Yes. > You mean the merged U-Boot changes, doesn't work with my Raspberry Pi > series? > Unfortunately that is exactly the state right now. >> U-Boot in its default >> config uses the devicetree provided by the FW, mostly because this way you don't >> have to do anything to find out how many RAM you really have. Secondly because >> this will allow us, in the near future, to have one U-boot binary for both RPi3 >> and RPi4 (and as a side effect one binary for RPi1 and RPi2). >> >> Anyway, I found at least, that the following compatibles need to be added: >> >> "brcm,bcm2838-cprman" >> "brcm,bcm2838-gpio" >> >> Without at least the cprman driver update, you won't see anything. >> >> "brcm,bcm2838-rng200" is also a candidate. >> >> I also suppose we will need to add "brcm,bcm2838" to >> arch/arm/mach-bcm/bcm2711.c, but I haven't verified this. > How about changing this in the downstream kernel? Which is much easier. >> >> Regards, >> Matthias >> >>> Regards, >>> Matthias >>> >>>> Are there any config.txt tweaks necessary? >>>> >>>> >>> _______________________________________________ >>> linux-arm-kernel mailing list >>> linux-arm-kernel@xxxxxxxxxxxxxxxxxxx >>> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel >>> >> _______________________________________________ >> linux-arm-kernel mailing list >> linux-arm-kernel@xxxxxxxxxxxxxxxxxxx >> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel >
