RE: [PATCH 2/5] mmc: dw-mmc: ensure that the card is not busy when changing clock.

[Seungwon Jeon <tgih.jun@samsung.com>]

Hi Jaehoon,

On Thursday, August 23, 2012, Jaehoon Chung <jh80.chung@samsung.com> wrote:
> To avoid glitches in the card clock output,
> need to check whether card is busy or not.
Could you describe the problem more?
In which situation did you meet this?

Thanks,
Seungwon Jeon
> 
> Signed-off-by: Jaehoon Chung <jh80.chung@samsung.com>
> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
> ---
>  drivers/mmc/host/dw_mmc.c |   30 ++++++++++++++++++++++++------
>  drivers/mmc/host/dw_mmc.h |    1 +
>  2 files changed, 25 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
> index 36f98c0..8bef3c2 100644
> --- a/drivers/mmc/host/dw_mmc.c
> +++ b/drivers/mmc/host/dw_mmc.c
> @@ -623,6 +623,27 @@ static void mci_send_cmd(struct dw_mci_slot *slot, u32 cmd, u32 arg)
>  		cmd, arg, cmd_status);
>  }
> 
> +static void dw_mci_inform_ciu(struct dw_mci_slot *slot)
> +{
> +	struct dw_mci *host = slot->host;
> +	unsigned long timeout = jiffies + msecs_to_jiffies(500);
> +	u32 ctrl, status;
> +
> +	do {
> +		status = mci_readl(host, STATUS);
> +		if (!(status & SDMMC_DATA_BUSY))
> +			break;
> +		ctrl = mci_readl(host, CTRL);
> +		ctrl |= SDMMC_CTRL_RESET;
> +		mci_writel(host, CTRL, ctrl);
> +	} while (time_before(jiffies, timeout));
> +
> +	if (status & SDMMC_DATA_BUSY)
> +		dev_err(&slot->mmc->class_dev,"Card is busy..!\n");
> +
> +	mci_send_cmd(slot, SDMMC_CMD_UPD_CLK | SDMMC_CMD_PRV_DAT_WAIT, 0);
> +}
> +
>  static void dw_mci_setup_bus(struct dw_mci_slot *slot)
>  {
>  	struct dw_mci *host = slot->host;
> @@ -650,15 +671,13 @@ static void dw_mci_setup_bus(struct dw_mci_slot *slot)
>  		mci_writel(host, CLKSRC, 0);
> 
>  		/* inform CIU */
> -		mci_send_cmd(slot,
> -			     SDMMC_CMD_UPD_CLK | SDMMC_CMD_PRV_DAT_WAIT, 0);
> +		dw_mci_inform_ciu(slot);
> 
>  		/* set clock to desired speed */
>  		mci_writel(host, CLKDIV, div);
> 
>  		/* inform CIU */
> -		mci_send_cmd(slot,
> -			     SDMMC_CMD_UPD_CLK | SDMMC_CMD_PRV_DAT_WAIT, 0);
> +		dw_mci_inform_ciu(slot);
> 
>  		/* enable clock; only low power if no SDIO */
>  		clk_en_a = SDMMC_CLKEN_ENABLE << slot->id;
> @@ -667,8 +686,7 @@ static void dw_mci_setup_bus(struct dw_mci_slot *slot)
>  		mci_writel(host, CLKENA, clk_en_a);
> 
>  		/* inform CIU */
> -		mci_send_cmd(slot,
> -			     SDMMC_CMD_UPD_CLK | SDMMC_CMD_PRV_DAT_WAIT, 0);
> +		dw_mci_inform_ciu(slot);
> 
>  		host->current_speed = slot->clock;
>  	}
> diff --git a/drivers/mmc/host/dw_mmc.h b/drivers/mmc/host/dw_mmc.h
> index 15c27e1..b6a1a78 100644
> --- a/drivers/mmc/host/dw_mmc.h
> +++ b/drivers/mmc/host/dw_mmc.h
> @@ -127,6 +127,7 @@
>  #define SDMMC_CMD_INDX(n)		((n) & 0x1F)
>  /* Status register defines */
>  #define SDMMC_GET_FCNT(x)		(((x)>>17) & 0x1FFF)
> +#define SDMMC_DATA_BUSY			BIT(9)
>  /* Internal DMAC interrupt defines */
>  #define SDMMC_IDMAC_INT_AI		BIT(9)
>  #define SDMMC_IDMAC_INT_NI		BIT(8)
> --
> 1.7.4.1
> --
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