On Wed, Oct 04, 2023 at 02:49:56PM +0100, Robin Murphy wrote: > On 04/10/2023 2:02 pm, Lad, Prabhakar wrote: > > + CC linux-mm and Robin Murphy > > > > On Wed, Oct 4, 2023 at 12:42 PM Jisheng Zhang <jszhang@xxxxxxxxxx> wrote: > > > > > > On Mon, Oct 02, 2023 at 09:37:44PM -0700, Drew Fustini wrote: > > > > On Fri, Sep 22, 2023 at 05:48:21PM -0500, Robert Nelson wrote: > > > > > On Fri, Sep 22, 2023 at 2:08 PM Robert Nelson <robertcnelson@xxxxxxxxx> wrote: > > > > > > > > > > > > On Thu, Sep 21, 2023 at 8:51 PM Drew Fustini <dfustini@xxxxxxxxxxxx> wrote: > > > > > > > > > > > > > > This series adds support for the eMMC on the BeagleV Ahead and the > > > > > > > Sipeed LicheePi 4A. This allows the kernel to boot with the rootfs on > > > > > > > eMMC. > > > > > > > > > > > > > > I tested on top of v6.6-rc2 with this config [1]. I was able to boot > > > > > > > both the Ahead [2] and LPi4a [3] from eMMC. The following prerequisites > > > > > > > are required: > > > > > > > > > > > > > > [PATCH v2] riscv: dts: thead: set dma-noncoherent to soc bus [4] > > > > > > > > > > > > > > I pushed a branch [5] with this patch series and the above patch for > > > > > > > those that find a git branch easier to test. > > > > > > > > > > > > > > Please note that only the MMC controller connected to the eMMC device > > > > > > > is enabled in the device trees for these two boards. I did not yet > > > > > > > attempt to configure and use the microSD card slot. My preference is to > > > > > > > address that in a future patch series. > > > > > > > > > > > > > > References: > > > > > > > [1] https://gist.github.com/pdp7/5fbdcf2a65eb1abdd3a29d519c19cdd2 > > > > > > > [2] https://gist.github.com/pdp7/91a801a5f8d1070c53509eda9800ad78 > > > > > > > [3] https://gist.github.com/pdp7/1445c3c991e88fd69c60165cef65726a > > > > > > > [4] https://lore.kernel.org/linux-riscv/20230912072232.2455-1-jszhang@xxxxxxxxxx/ > > > > > > > [5] https://github.com/pdp7/linux/tree/b4/th1520-mmc > > > > > > > > > > > > This patchset came out very nice! > > > > > > > > > > > > v6.6-rc2 with Last RFC v2: > > > > > > > > > > > > [ 4.066630] mmc0: SDHCI controller on ffe7080000.mmc > > > > > > [ffe7080000.mmc] using PIO > > > > > > > > > > > > debian@BeagleV:~$ sudo hdparm -tT /dev/mmcblk0 > > > > > > > > > > > > /dev/mmcblk0: > > > > > > Timing cached reads: 1516 MB in 2.00 seconds = 758.09 MB/sec > > > > > > Timing buffered disk reads: 84 MB in 3.01 seconds = 27.94 MB/sec > > > > > > > > > > > > vs v6.6-rc2 with this patchset: > > > > > > > > > > > > [ 4.096837] mmc0: SDHCI controller on ffe7080000.mmc > > > > > > [ffe7080000.mmc] using DMA > > > > > > > > > > > > debian@BeagleV:~$ sudo hdparm -tT /dev/mmcblk0 > > > > > > > > > > > > /dev/mmcblk0: > > > > > > Timing cached reads: 1580 MB in 2.00 seconds = 790.97 MB/sec > > > > > > Timing buffered disk reads: 418 MB in 3.00 seconds = 139.11 MB/sec > > > > > > > > > > Drew pointed out on Slack, this was not quite right.. After more > > > > > digging by Drew, CONFIG_DMA_GLOBAL_POOL is causing a DMA limitation > > > > > with the multiplatform defconfig. so with, > > > > > > > > > > ./scripts/config --disable CONFIG_ARCH_R9A07G043 > > > > > > > > > > (to remove CONFIG_DMA_GLOBAL_POOL)... another 2x in buffered reads.. > > > > > > > > > > [ 4.059242] mmc0: SDHCI controller on ffe7080000.mmc > > > > > [ffe7080000.mmc] using ADMA 64-bit > > > > > > > > > > debian@BeagleV:~$ sudo hdparm -tT /dev/mmcblk0 > > > > > > > > > > /dev/mmcblk0: > > > > > Timing cached reads: 1600 MB in 2.00 seconds = 800.93 MB/sec > > > > > Timing buffered disk reads: 892 MB in 3.00 seconds = 297.06 MB/sec > > > > > > > > It seems CONFIG_DMA_GLOBAL_POOL=y causes ADMA buffer alloc to fail [1]: > > > > > > > > mmc0: Unable to allocate ADMA buffers - falling back to standard DMA > > > > > > > > Prabhakar's AX45MP non-coherent DMA support [2] series introduced the > > > > selection of DMA_GLOBAL_POOL for ARCH_R9A07G043 and the riscv defconfig > > > > selects ARCH_R9A07G043. > > > > > > > > Patch 5 in the series [3] states that: > > > > > > > > With DMA_GLOBAL_POOL enabled all DMA allocations happen from this > > > > region and synchronization callbacks are implemented to synchronize > > > > when doing DMA transactions. > > > > > > > > This example of a "shared-dma-pool" node was given: > > > > > > > > pma_resv0@58000000 { > > > > compatible = "shared-dma-pool"; > > > > reg = <0x0 0x58000000 0x0 0x08000000>; > > > > no-map; > > > > linux,dma-default; > > > > }; > > > > > > > > I've copied that to th1520-beaglev-ahead.dts. The address of 0x58000000 > > > > has no significance on th1520, but the existence of shared-dma-pool > > > > seems to fix the problem. ADMA mode [4] is now working even though > > > > CONFIG_DMA_GLOBAL_POOL=y. > > > > > > + Christoph, Lad > > > > > > IMHO, this is not TH1520 specific but a generic issue. > > > > > > I believe commit 484861e09f3e ("soc: renesas: Kconfig: Select the > > > required configs for RZ/Five SoC") can cause regression on all > > > non-dma-coherent riscv platforms with generic defconfig. This is > > > a common issue. The logic here is: generic riscv defconfig selects > > > ARCH_R9A07G043 which selects DMA_GLOBAL_POOL, which assumes all > > > non-dma-coherent riscv platforms have a dma global pool, this assumption > > > seems not correct. And I believe DMA_GLOBAL_POOL should not be > > > selected by ARCH_SOCFAMILIY, instead, only ARCH under some specific > > > conditions can select it globaly, for example NOMMU ARM and so on. > > > > > > Since this is a regression, what's proper fix? any suggestion is > > > appreciated. > > I think the answer is to not select DMA_GLOBAL_POOL, since that is only > designed for nommu cases where non-cacheable memory lives in a fixed place > in the physical address map, and regular kernel pages can't be remapped. As > far as I'm aware, RISCV_DMA_NONCOHERENT is the thing you want, such that > DMA_DIRECT_REMAP can dynamically provide non-cacheable coherent buffers for > non-hardware-coherent devices. Thank Robin! AFAIK, ARCH_R9A07G043 needs the dma global pool to handle its CMO. So it looks like ARCH_R9A07G043 can't be enabled in riscv generic defconfig. And we also need a special solution to prevent random config from selecting ARCH_R9A07G043 by chance for other platforms Thanks > > Thanks, > Robin. > > > > > > > Thanks > > > > > > > > > > > Thanks, > > > > Drew > > > > > > > > [1] https://gist.github.com/pdp7/73041ed808bbc7dd445836fb90574979 > > > > [2] https://lore.kernel.org/linux-riscv/20230818135723.80612-1-prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx/ > > > > [3] https://lore.kernel.org/linux-riscv/20230818135723.80612-6-prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx/ > > > > [4] https://gist.github.com/pdp7/91e72a663d3bb73eb28182337ad8bbcb
