Am 18.12.2020 um 08:53 schrieb Dmitry Lebed:
> Enable SGDMA support for SD_IO_RW_EXTENDED and add proper check
> for scatterlist size alignment in block mode.
>
> According to documentation, in SDIO block mode meson-gx DMA could
> only handle buffers with sizes that are multiples of SDIO block size.
>
> Some SDIO drivers like brcmfmac use scatterlist API, but do not enforce
> proper scatterlist buffer size alignemnt, this looks like a root cause
> of non-working CMD53.
>
It's been too long ago that I worked on this to provide real feedback.
Just one comment: Your commit description sounds like there's a problem
in drivers like brcmfmac. Wouldn't it be better then to first fix these
drivers?
> Some minor style fixes.
>
> Signed-off-by: Dmitry Lebed <lebed.dmitry@xxxxxxxxx>
> ---
> drivers/mmc/host/meson-gx-mmc.c | 37 ++++++++++++++++++++-------------
> 1 file changed, 22 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/mmc/host/meson-gx-mmc.c b/drivers/mmc/host/meson-gx-mmc.c
> index 13f6a2c0ed04..eb6c02bc4a02 100644
> --- a/drivers/mmc/host/meson-gx-mmc.c
> +++ b/drivers/mmc/host/meson-gx-mmc.c
> @@ -227,7 +227,6 @@ static void meson_mmc_get_transfer_mode(struct mmc_host *mmc,
> struct mmc_data *data = mrq->data;
> struct scatterlist *sg;
> int i;
> - bool use_desc_chain_mode = true;
>
> /*
> * When Controller DMA cannot directly access DDR memory, disable
> @@ -237,25 +236,33 @@ static void meson_mmc_get_transfer_mode(struct mmc_host *mmc,
> if (host->dram_access_quirk)
> return;
>
> - /*
> - * Broken SDIO with AP6255-based WiFi on Khadas VIM Pro has been
> - * reported. For some strange reason this occurs in descriptor
> - * chain mode only. So let's fall back to bounce buffer mode
> - * for command SD_IO_RW_EXTENDED.
> - */
> - if (mrq->cmd->opcode == SD_IO_RW_EXTENDED)
> - return;
> + if (data->blocks > 1) {
> + /*
> + * In block mode DMA descriptor format, "length" field indicates
> + * number of blocks and there is no way to pass DMA size that
> + * is not multiple of SDIO block size, making it impossible to
> + * tie more than one memory buffer with single SDIO block.
> + * Block mode sg buffer size should be aligned with SDIO block
> + * size, otherwise chain mode could not be used.
> + */
> + for_each_sg(data->sg, sg, data->sg_len, i) {
> + if (sg->length % data->blksz) {
> + WARN_ONCE(1, "unaligned sg len %u blksize %u\n",
> + sg->length, data->blksz);
> + return;
> + }
> + }
> + }
>
> - for_each_sg(data->sg, sg, data->sg_len, i)
> + for_each_sg(data->sg, sg, data->sg_len, i) {
> /* check for 8 byte alignment */
> - if (sg->offset & 7) {
> + if (sg->offset % 8) {
> WARN_ONCE(1, "unaligned scatterlist buffer\n");
> - use_desc_chain_mode = false;
> - break;
> + return;
> }
> + }
>
> - if (use_desc_chain_mode)
> - data->host_cookie |= SD_EMMC_DESC_CHAIN_MODE;
> + data->host_cookie |= SD_EMMC_DESC_CHAIN_MODE;
> }
>
> static inline bool meson_mmc_desc_chain_mode(const struct mmc_data *data)
>
