[PATCH v2] mmc: sunxi: Don't start commands while the card is busy

[Ulf Hansson]

On 10 July 2015 at 17:14, Hans de Goede <hdegoede at redhat.com> wrote:
> Some sdio wifi modules have not been working reliable with the sunxi-mmc
> host code. This turns out to be caused by it starting new commands while
> the card signals that it is still busy processing a previous command.

Which are those commands? Or more interesting, which response types do
these commands expect?
I don't think this is a sunxi specific issue, I have seen similar
issues for other host controllers.

I am thinking that perhaps this should be managed by the mmc core
instead of local hacks to sunxi. Potentially we could make the core to
invoke the already existing host_ops->card_busy() callback when
needed...

Within this context, could I ask whether you controller supports IRQ
based HW-busy detection? Or you need polling of the status register?

>
> This commit fixes this, thereby fixing the wifi reliability issues on
> the Cubietruck and other sunxi boards using sdio wifi.
>
> Reported-by: Eugene K <sigintmailru at gmail.com>
> Suggested-by: Eugene K <sigintmailru at gmail.com>
> Cc: Eugene K <sigintmailru at gmail.com>
> Cc: Arend van Spriel <arend at broadcom.com>
> Signed-off-by: Hans de Goede <hdegoede at redhat.com>
> ---
> Changes in v2:
> -Properly accredit Eugene K for coming up with the fix for this
> ---
>  drivers/mmc/host/sunxi-mmc.c | 32 ++++++++++++++++++++++++++++++++
>  1 file changed, 32 insertions(+)
>
> diff --git a/drivers/mmc/host/sunxi-mmc.c b/drivers/mmc/host/sunxi-mmc.c
> index 4d3e1ff..daa90b7 100644
> --- a/drivers/mmc/host/sunxi-mmc.c
> +++ b/drivers/mmc/host/sunxi-mmc.c
> @@ -289,6 +289,24 @@ static int sunxi_mmc_init_host(struct mmc_host *mmc)
>         return 0;
>  }
>
> +/* Wait for card to report ready before starting a new cmd */
> +static int sunxi_mmc_wait_card_ready(struct sunxi_mmc_host *host)
> +{
> +       unsigned long expire = jiffies + msecs_to_jiffies(500);
> +       u32 rval;
> +
> +       do {
> +               rval = mmc_readl(host, REG_STAS);
> +       } while (time_before(jiffies, expire) && (rval & SDXC_CARD_DATA_BUSY));
> +
> +       if (rval & SDXC_CARD_DATA_BUSY) {
> +               dev_err(mmc_dev(host->mmc), "Error R1 ready timeout\n");
> +               return -EIO;
> +       }
> +
> +       return 0;
> +}
> +
>  static void sunxi_mmc_init_idma_des(struct sunxi_mmc_host *host,
>                                     struct mmc_data *data)
>  {
> @@ -383,6 +401,8 @@ static void sunxi_mmc_send_manual_stop(struct sunxi_mmc_host *host,
>         u32 arg, cmd_val, ri;
>         unsigned long expire = jiffies + msecs_to_jiffies(1000);
>
> +       sunxi_mmc_wait_card_ready(host);
> +
>         cmd_val = SDXC_START | SDXC_RESP_EXPIRE |
>                   SDXC_STOP_ABORT_CMD | SDXC_CHECK_RESPONSE_CRC;
>
> @@ -597,6 +617,11 @@ static int sunxi_mmc_oclk_onoff(struct sunxi_mmc_host *host, u32 oclk_en)
>  {
>         unsigned long expire = jiffies + msecs_to_jiffies(250);
>         u32 rval;
> +       int ret;
> +
> +       ret = sunxi_mmc_wait_card_ready(host);
> +       if (ret)
> +               return ret;
>
>         rval = mmc_readl(host, REG_CLKCR);
>         rval &= ~(SDXC_CARD_CLOCK_ON | SDXC_LOW_POWER_ON);
> @@ -785,6 +810,13 @@ static void sunxi_mmc_request(struct mmc_host *mmc, struct mmc_request *mrq)
>                 return;
>         }
>
> +       ret = sunxi_mmc_wait_card_ready(host);
> +       if (ret) {
> +               mrq->cmd->error = ret;
> +               mmc_request_done(mmc, mrq);
> +               return;
> +       }
> +
>         if (data) {
>                 ret = sunxi_mmc_map_dma(host, data);
>                 if (ret < 0) {
> --
> 2.4.3
>

Kind regards
Uffe