linux-kernel - Re: [PATCH 1/3] mmc: sdhci: sdhci-pci-o2micro: Correctly set bus width when tuning

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Date:   Wed, 12 Jun 2019 15:36:25 +0200
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Raul E Rangel <rrangel@...omium.org>
Cc:     "linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
        "ernest.zhang" <ernest.zhang@...hubtech.com>,
        Daniel Kurtz <djkurtz@...omium.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Adrian Hunter <adrian.hunter@...el.com>
Subject: Re: [PATCH 1/3] mmc: sdhci: sdhci-pci-o2micro: Correctly set bus
 width when tuning

On Mon, 10 Jun 2019 at 20:54, Raul E Rangel <rrangel@...omium.org> wrote:
>
> sdhci_send_tuning uses mmc->ios.bus_width to determine the block size.
> Without this patch the block size would be set incorrectly when the
> bus_width == 8 which results in tuning failing.
>
> Signed-off-by: Raul E Rangel <rrangel@...omium.org>
> ---
>
>  drivers/mmc/host/sdhci-pci-o2micro.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/mmc/host/sdhci-pci-o2micro.c b/drivers/mmc/host/sdhci-pci-o2micro.c
> index b29bf4e7dcb48..dd21315922c87 100644
> --- a/drivers/mmc/host/sdhci-pci-o2micro.c
> +++ b/drivers/mmc/host/sdhci-pci-o2micro.c
> @@ -115,6 +115,7 @@ static int sdhci_o2_execute_tuning(struct mmc_host *mmc, u32 opcode)
>          */
>         if (mmc->ios.bus_width == MMC_BUS_WIDTH_8) {
>                 current_bus_width = mmc->ios.bus_width;
> +               mmc->ios.bus_width = MMC_BUS_WIDTH_4;

This looks wrong.

mmc->ios.bus_width is not supposed to be updated by a host driver, but
rather the value should only be read.

>                 sdhci_set_bus_width(host, MMC_BUS_WIDTH_4);
>         }
>
> @@ -126,8 +127,10 @@ static int sdhci_o2_execute_tuning(struct mmc_host *mmc, u32 opcode)
>
>         sdhci_end_tuning(host);
>
> -       if (current_bus_width == MMC_BUS_WIDTH_8)
> +       if (current_bus_width == MMC_BUS_WIDTH_8) {
> +               mmc->ios.bus_width = MMC_BUS_WIDTH_8;

Ditto.

>                 sdhci_set_bus_width(host, current_bus_width);
> +       }
>
>         host->flags &= ~SDHCI_HS400_TUNING;
>         return 0;
> --
> 2.22.0.rc2.383.gf4fbbf30c2-goog
>

Kind regards
Uffe