diff mbox series

[2/2] mmc: meson-gx: also check SD_IO_RW_EXTENDED for scatterlist size alignment

Message ID 20210426175559.3110575-2-narmstrong@baylibre.com (mailing list archive)
State New
Headers show
Series [1/2] mmc: meson-gx: make replace WARN_ONCE with dev_warn_once about scatterlist offset alignment | expand

Commit Message

Neil Armstrong April 26, 2021, 5:55 p.m. UTC
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@gmail.com>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
---
 drivers/mmc/host/meson-gx-mmc.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Comments

Ulf Hansson May 11, 2021, 10:56 a.m. UTC | #1
On Mon, 26 Apr 2021 at 19:56, Neil Armstrong <narmstrong@baylibre.com> 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@gmail.com>
> Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>

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
>
diff mbox series

Patch

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