Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
MIME-Version: 1.0
References: <20210426175559.3110575-1-narmstrong@baylibre.com>
In-Reply-To: <20210426175559.3110575-1-narmstrong@baylibre.com>
From:   Ulf Hansson <ulf.hansson@linaro.org>
Date:   Tue, 11 May 2021 12:56:13 +0200
Message-ID: <CAPDyKFrJMFX5ztz6wiWVmwvVF+pms23_+qw8Ey_1pzrHqQ9vRg@mail.gmail.com>
Subject: Re: [PATCH 1/2] mmc: meson-gx: make replace WARN_ONCE with
 dev_warn_once about scatterlist offset alignment
To:     Neil Armstrong <narmstrong@baylibre.com>
Cc:     Kevin Hilman <khilman@baylibre.com>,
        linux-mmc <linux-mmc@vger.kernel.org>,
        "open list:ARM/Amlogic Meson..." <linux-amlogic@lists.infradead.org>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Christian Hewitt <christianshewitt@gmail.com>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Mon, 26 Apr 2021 at 19:56, Neil Armstrong <narmstrong@baylibre.com> wrote:
>
> Some drivers like ath10k can sometimg give an sg buffer with an offset whose alignment
> is not compatible with the Amlogic DMA descriptor engine requirements.
>
> Simply replace with dev_warn_once() to inform user this should be fixed to avoid
> degraded performance.
>
> This should be ultimately fixed in ath10k, but since it's only a performance issue
> the warning should be removed.
>
> Fixes: 79ed05e329c3 ("mmc: meson-gx: add support for descriptor chain 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 | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/mmc/host/meson-gx-mmc.c b/drivers/mmc/host/meson-gx-mmc.c
> index b8b771b643cc..1c61f0f24c09 100644
> --- a/drivers/mmc/host/meson-gx-mmc.c
> +++ b/drivers/mmc/host/meson-gx-mmc.c
> @@ -258,7 +258,9 @@ static void meson_mmc_get_transfer_mode(struct mmc_host *mmc,
>         for_each_sg(data->sg, sg, data->sg_len, i) {
>                 /* check for 8 byte alignment */
>                 if (sg->offset % 8) {
> -                       WARN_ONCE(1, "unaligned scatterlist buffer\n");
> +                       dev_warn_once(mmc_dev(mmc),
> +                                     "unaligned sg offset %u, disabling descriptor DMA for transfer\n",
> +                                     sg->offset);
>                         return;
>                 }
>         }
> --
> 2.25.1
>