On Mon, 26 Apr 2021 at 19:56, Neil Armstrong <narmstrong@xxxxxxxxxxxx> wrote:
>
> The brcmfmac driver can generate a scatterlist from a skb with each packets
> not aligned to the block size. This is not supported by the Amlogic Descriptor
> dma engine where each descriptor must match a multiple of the block size.
>
> The sg list is valid, since the sum of the sg buffers is a multiple of the
> block size, but we must discard those when in SD_IO_RW_EXTENDED mode since
> SDIO block mode can be used under the hood even with data->blocks == 1.
>
> Those transfers are very rare, thus can be replaced by a bounce buffer
> without real performance loss.
>
> Fixes: 7412dee9f1fd ("mmc: meson-gx: replace WARN_ONCE with dev_warn_once about scatterlist size alignment in block mode")
> Reported-by: Christian Hewitt <christianshewitt@xxxxxxxxx>
> Signed-off-by: Neil Armstrong <narmstrong@xxxxxxxxxxxx>
Applied for fixes and by adding a stable tag, thanks!
Kind regards
Uffe
> ---
> drivers/mmc/host/meson-gx-mmc.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/mmc/host/meson-gx-mmc.c b/drivers/mmc/host/meson-gx-mmc.c
> index 1c61f0f24c09..016a6106151a 100644
> --- a/drivers/mmc/host/meson-gx-mmc.c
> +++ b/drivers/mmc/host/meson-gx-mmc.c
> @@ -236,7 +236,8 @@ static void meson_mmc_get_transfer_mode(struct mmc_host *mmc,
> if (host->dram_access_quirk)
> return;
>
> - if (data->blocks > 1) {
> + /* SD_IO_RW_EXTENDED (CMD53) can also use block mode under the hood */
> + if (data->blocks > 1 || mrq->cmd->opcode == SD_IO_RW_EXTENDED) {
> /*
> * In block mode DMA descriptor format, "length" field indicates
> * number of blocks and there is no way to pass DMA size that
> --
> 2.25.1
>
