On 2024-10-20 23:29, Aurelien Jarno wrote:
The Synopsys DesignWare mmc controller on the JH7110 SoC (dw_mmc-starfive.c driver) is using a 32-bit IDMAC address bus width, and thus requires the use of SWIOTLB.
The commit 8396c793ffdf ("mmc: dw_mmc: Fix IDMAC operation with pages bigger than 4K") increased the max_seq_size, even for 4K pages, causing "swiotlb buffer is full" to happen because swiotlb can only handle a memory size up to 256kB only.
Fix the issue, by making sure the dw_mmc driver doesn't use segments bigger than what SWIOTLB can handle.
Reported-by: Ron Economos re@w6rz.net Reported-by: Jing Luo jing@jing.rocks Fixes: 8396c793ffdf ("mmc: dw_mmc: Fix IDMAC operation with pages bigger than 4K") Cc: stable@vger.kernel.org Signed-off-by: Aurelien Jarno aurelien@aurel32.net
Feel free to add:
Tested-by: Jing Luo jing@jing.rocks
This patch not only fixes the kernel log spam by dwmmc_starfive reporting "swiotlb buffer is full", but also seems to have fixed a serious bug that causes data corruption on emmc (as I reported to Debian [1]), which at least can be observed on both Visionfive 2 and Star64 boards. To add a cherry on the top, with this patch applied, I see massive performance improvement (sequential rw speed) on emmc: with a quick-and-dirty test using `dd bs=1M`, on Visionfive 2, it goes from 28MB/s to 42MB/s (+50%); on Star64, it goes from 13MB/s to 46MB/s (+253%).
[1] https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1085425
Thanks & cheers,
Jing Luo
drivers/mmc/host/dw_mmc.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c index 41e451235f637..dc0d6201f7b73 100644 --- a/drivers/mmc/host/dw_mmc.c +++ b/drivers/mmc/host/dw_mmc.c @@ -2958,7 +2958,8 @@ static int dw_mci_init_slot(struct dw_mci *host) mmc->max_segs = host->ring_size; mmc->max_blk_size = 65535; mmc->max_req_size = DW_MCI_DESC_DATA_LENGTH * host->ring_size;
mmc->max_seg_size = mmc->max_req_size;
mmc->max_seg_size =min_t(size_t, mmc->max_req_size,dma_max_mapping_size(host->dev)); mmc->max_blk_count = mmc->max_req_size / 512; } else if (host->use_dma == TRANS_MODE_EDMAC) { mmc->max_segs = 64;