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

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Message-ID: <CAPDyKFpu3bz64R-t9KxEkobKKoOY6Dy6H9j2W2LEzeoz4-D4Yw@mail.gmail.com>
Date:   Fri, 16 Apr 2021 15:13:27 +0200
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Neil Armstrong <narmstrong@...libre.com>
Cc:     linux-mmc <linux-mmc@...r.kernel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        "open list:ARM/Amlogic Meson..." <linux-amlogic@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Dmitry Lebed <lebed.dmitry@...il.com>,
        Marek Szyprowski <m.szyprowski@...sung.com>
Subject: Re: [PATCH v2] mmc: meson-gx: replace WARN_ONCE with dev_warn_once
 about scatterlist size alignment in block mode

On Fri, 16 Apr 2021 at 11:43, Neil Armstrong <narmstrong@...libre.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@...sung.com>
> Signed-off-by: Neil Armstrong <narmstrong@...libre.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
>