[PATCH] mmc: dw_mmc: take SWIOTLB memory size limitation into account

[Anand Moon]

Hi Aurelien,

On Sun, 20 Oct 2024 at 20:01, Aurelien Jarno <aurelien at aurel32.net> 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 at w6rz.net>
> Reported-by: Jing Luo <jing at jing.rocks>
> Fixes: 8396c793ffdf ("mmc: dw_mmc: Fix IDMAC operation with pages bigger than 4K")
> Cc: stable at vger.kernel.org
> Signed-off-by: Aurelien Jarno <aurelien at aurel32.net>
> ---
Please add my

Tested-by: Anand Moon <linux.amoon at gmail.com>

Thanks for fixing the warning below.

[  511.837216][  T148] dwmmc_starfive 16020000.mmc: swiotlb buffer is
full (sz: 290816 bytes), total 65536 (slots), used 246 (slots)
[  511.837423][    C0] dwmmc_starfive 16020000.mmc: swiotlb buffer is
full (sz: 278528 bytes), total 65536 (slots), used 222 (slots)
[  511.916951][    C0] dwmmc_starfive 16020000.mmc: swiotlb buffer is
full (sz: 290816 bytes), total 65536 (slots), used 24 (slots)
[  516.803916][  T575] dwmmc_starfive 16020000.mmc: swiotlb buffer is
full (sz: 507904 bytes), total 65536 (slots), used 122 (slots)
[  516.805450][    C0] dwmmc_starfive 16020000.mmc: swiotlb buffer is
full (sz: 507904 bytes), total 65536 (slots), used 364 (slots)

Thanks
-Anand

>  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;
> --
> 2.45.2
>
>
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