[PATCH v2] mmc: meson-gx: replace WARN_ONCE with dev_warn_once about scatterlist size alignment in block mode

[PATCH v2] mmc: meson-gx: replace WARN_ONCE with dev_warn_once about scatterlist size alignment in block mode

[Neil Armstrong]

Since commit e085b51c74cc ("mmc: meson-gx: check for scatterlist size alignment in block mode"),
support for SDIO SD_IO_RW_EXTENDED transferts are properly filtered but some driver
like brcmfmac still gives a block sg buffer size not aligned with SDIO block,
triggerring a WARN_ONCE() with scary stacktrace even if the transfer works fine
but with possible degraded performances.

Simply replace with dev_warn_once() to inform user this should be fixed to avoid
degraded performance.

This should be ultimately fixed in brcmfmac, but since it's only a performance issue
the warning should be removed.

Fixes: e085b51c74cc ("mmc: meson-gx: check for scatterlist size alignment in block mode")
Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
---
Changes since v1:
- replace WARN_ONCE with dev_warn_once and explicit the warning message

 drivers/mmc/host/meson-gx-mmc.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/mmc/host/meson-gx-mmc.c b/drivers/mmc/host/meson-gx-mmc.c
index eb6c02bc4a02..b8b771b643cc 100644
--- a/drivers/mmc/host/meson-gx-mmc.c
+++ b/drivers/mmc/host/meson-gx-mmc.c
@@ -247,8 +247,9 @@ static void meson_mmc_get_transfer_mode(struct mmc_host *mmc,
 		 */
 		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);
+				dev_warn_once(mmc_dev(mmc),
+					      "unaligned sg len %u blksize %u, disabling descriptor DMA for transfer\n",
+					      sg->length, data->blksz);
 				return;
 			}
 		}
-- 
2.25.1


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Re: [PATCH v2] mmc: meson-gx: replace WARN_ONCE with dev_warn_once about scatterlist size alignment in block mode

[Ulf Hansson]

On Fri, 16 Apr 2021 at 11:43, Neil Armstrong <narmstrong@baylibre.com> wrote:
>
> Since commit e085b51c74cc ("mmc: meson-gx: check for scatterlist size alignment in block mode"),
> support for SDIO SD_IO_RW_EXTENDED transferts are properly filtered but some driver
> like brcmfmac still gives a block sg buffer size not aligned with SDIO block,
> triggerring a WARN_ONCE() with scary stacktrace even if the transfer works fine
> but with possible degraded performances.
>
> Simply replace with dev_warn_once() to inform user this should be fixed to avoid
> degraded performance.
>
> This should be ultimately fixed in brcmfmac, but since it's only a performance issue
> the warning should be removed.
>
> Fixes: e085b51c74cc ("mmc: meson-gx: check for scatterlist size alignment in block mode")
> Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
> Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>

Applied for next, thanks! (I move to fixes if there is another rc on Monday).

Kind regards
Uffe


> ---
> Changes since v1:
> - replace WARN_ONCE with dev_warn_once and explicit the warning message
>
>  drivers/mmc/host/meson-gx-mmc.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/mmc/host/meson-gx-mmc.c b/drivers/mmc/host/meson-gx-mmc.c
> index eb6c02bc4a02..b8b771b643cc 100644
> --- a/drivers/mmc/host/meson-gx-mmc.c
> +++ b/drivers/mmc/host/meson-gx-mmc.c
> @@ -247,8 +247,9 @@ static void meson_mmc_get_transfer_mode(struct mmc_host *mmc,
>                  */
>                 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);
> +                               dev_warn_once(mmc_dev(mmc),
> +                                             "unaligned sg len %u blksize %u, disabling descriptor DMA for transfer\n",
> +                                             sg->length, data->blksz);
>                                 return;
>                         }
>                 }
> --
> 2.25.1
>

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