Re: use default speed of the eMMC

[Jaehoon Chung <jh80.chung@samsung.com>]

Hi,

On 05/24/2016 06:07 PM, 장민우 wrote:
> Dear linux-mmc.
> 
> Hello, I'm Minwoo Jang.
> 
> I have a question about using default speed of the eMMC.
> 
> When default speed is used, mmc_select_bus_width() is never called.
> 
> So, eMMC can not be set 4 bit or 8 bit bus width, I think.
> 
> Please, give me your opinions on the following diff codes.

In mmc_select_timing(), timing should be set to MMC_TIMING_HS or others.
Then mmc_select_bus_width() should be entered.

Best Regards,
Jaehoon Chung

> 
> Thank you.
> 
> =====================================================
> 
> diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
> index 94b4462..3b1cc4d 100644
> --- a/drivers/mmc/core/mmc.c
> +++ b/drivers/mmc/core/mmc.c
> @@ -952,6 +952,8 @@ static int mmc_select_bus_width(struct mmc_card *card)
> 
>                 if (!err) {
>                         err = bus_width;
> +                       pr_warn("%s: switch to bus width %d\n",
> +                               mmc_hostname(host), (1 << bus_width));
>                         break;
>                 } else {
>                         pr_warn("%s: switch to bus width %d failed\n",
> @@ -1500,6 +1502,14 @@ static int mmc_init_card(struct mmc_host *host, u32 ocr,
>                         if (err)
>                                 goto err;
>                 }
> +       } else {
> +               /* Select the bus width for normal speed mode */
> +               err = mmc_select_bus_width(card);
> +               if (IS_ERR_VALUE(err)) {
> +                       pr_warn("%s: Selecting bus width failed\n",
> +                               mmc_hostname(card->host));
> +                       goto err;
> +               }
>         }
> 
> Best regards,
> 
> MW Jang.
> --
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> 
>