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@xxxxxxxx>
Reported-by: Jing Luo <jing@jing.rocks>
Fixes: 8396c793ffdf ("mmc: dw_mmc: Fix IDMAC operation with pages
bigger than 4K")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Aurelien Jarno <aurelien@xxxxxxxxxxx>
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;
