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. 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
