Subject: [PATCH] mmc: dw_mmc: change to use recommended reset procedure

From: [email-masked] (Jaehoon Chung)
Date: Thu, 29 May 2014 14:17:25 +0900

Hi, Sonny.

On 05/29/2014 09:35 AM, Sonny Rao wrote:
> This patch changes the fifo reset code to follow the reset procedure
> outlined in the documentation of Synopsys Mobile storage host databook.
> 
> Signed-off-by: Sonny Rao <[email-masked]>
> Signed-off-by: Yuvaraj Kumar C D <[email-masked]>
> ---
> v2: Add Generic DMA support
>     per the documentation, move interrupt clear before wait
>     make the test for DMA host->use_dma rather than host->using_dma
>     add proper return values (although it appears no caller checks)
> v3: rename fifo reset function, and change callers
>     use this combined reset function in dw_mci_resume()
>     just one caller left (probe), so get rid of dw_mci_ctrl_all_reset()
>     use DMA reset bit for all systems which use DMA
>     remove extra IDMAC reset in dw_mci_work_routine_card()
>     do CIU clock update in error path, if CIU reset cleared
> 
>  drivers/mmc/host/dw_mmc.c | 85 +++++++++++++++++++++++++++++++++++------------
>  drivers/mmc/host/dw_mmc.h |  1 +
>  2 files changed, 64 insertions(+), 22 deletions(-)
> 
> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
> index 55cd110..988492c 100644
> --- a/drivers/mmc/host/dw_mmc.c
> +++ b/drivers/mmc/host/dw_mmc.c
> @@ -111,8 +111,7 @@ static const u8 tuning_blk_pattern_8bit[] = {
>  	0xff, 0x77, 0x77, 0xff, 0x77, 0xbb, 0xdd, 0xee,
>  };
>  
> -static inline bool dw_mci_fifo_reset(struct dw_mci *host);
> -static inline bool dw_mci_ctrl_all_reset(struct dw_mci *host);
> +static inline bool dw_mci_reset(struct dw_mci *host);
>  
>  #if defined(CONFIG_DEBUG_FS)
>  static int dw_mci_req_show(struct seq_file *s, void *v)
> @@ -1254,7 +1253,7 @@ static int dw_mci_data_complete(struct dw_mci *host, struct mmc_data *data)
>  		 * After an error, there may be data lingering
>  		 * in the FIFO
>  		 */
> -		dw_mci_fifo_reset(host);
> +		dw_mci_reset(host);
>  	} else {
>  		data->bytes_xfered = data->blocks * data->blksz;
>  		data->error = 0;
> @@ -1371,7 +1370,7 @@ static void dw_mci_tasklet_func(unsigned long priv)
>  
>  			/* CMD error in data command */
>  			if (mrq->cmd->error && mrq->data)
> -				dw_mci_fifo_reset(host);
> +				dw_mci_reset(host);
>  
>  			host->cmd = NULL;
>  			host->data = NULL;
> @@ -1982,14 +1981,9 @@ static void dw_mci_work_routine_card(struct work_struct *work)
>  			}
>  
>  			/* Power down slot */
> -			if (present == 0) {
> +			if (present == 0)
>  				/* Clear down the FIFO */
Didn't Need to change the Comment?
> -				dw_mci_fifo_reset(host);
> -#ifdef CONFIG_MMC_DW_IDMAC
> -				dw_mci_idmac_reset(host);
> -#endif
> -
> -			}
> +				dw_mci_reset(host);
>  
>  			spin_unlock_bh(&host->lock);
>  
> @@ -2323,8 +2317,11 @@ static bool dw_mci_ctrl_reset(struct dw_mci *host, u32 reset)
>  	return false;
>  }
>  
> -static inline bool dw_mci_fifo_reset(struct dw_mci *host)
> +static inline bool dw_mci_reset(struct dw_mci *host)
>  {
> +	u32 flags = SDMMC_CTRL_RESET | SDMMC_CTRL_FIFO_RESET;
> +	bool ret = false;
> +
>  	/*
>  	 * Reseting generates a block interrupt, hence setting
>  	 * the scatter-gather pointer to NULL.
> @@ -2334,15 +2331,57 @@ static inline bool dw_mci_fifo_reset(struct dw_mci *host)
>  		host->sg = NULL;
>  	}
>  
> -	return dw_mci_ctrl_reset(host, SDMMC_CTRL_FIFO_RESET);
> -}
> +	if (host->use_dma)
> +		flags |= SDMMC_CTRL_DMA_RESET;
>  
> -static inline bool dw_mci_ctrl_all_reset(struct dw_mci *host)
> -{
> -	return dw_mci_ctrl_reset(host,
> -				 SDMMC_CTRL_FIFO_RESET |
> -				 SDMMC_CTRL_RESET |
> -				 SDMMC_CTRL_DMA_RESET);
> +	if (dw_mci_ctrl_reset(host, flags)) {
> +		/*
> +		 * In all cases we clear the RAWINTS register to clear any
> +		 * interrupts.
> +		 */
> +		mci_writel(host, RINTSTS, 0xFFFFFFFF);
> +
> +		/* if using dma we wait for dma_req to clear */
> +		if (host->use_dma) {
> +			unsigned long timeout = jiffies + msecs_to_jiffies(500);
> +			u32 status;
> +			do {
> +				status = mci_readl(host, STATUS);
> +				if (!(status & SDMMC_STATUS_DMA_REQ))
> +					break;
> +				cpu_relax();
> +			} while (time_before(jiffies, timeout));
> +
> +			if (status & SDMMC_STATUS_DMA_REQ) {
> +				dev_err(host->dev,
> +					"%s: Timeout waiting for dma_req to "
> +					"clear during reset", __func__);
> +				goto ciu_out;
> +			}
> +
> +			/* when using DMA next we reset the fifo again */
> +			if (!dw_mci_ctrl_reset(host, SDMMC_CTRL_FIFO_RESET))
> +				goto ciu_out;
> +		}
> +	} else {
> +		dev_err(host->dev, "%s: Reset bits didn't clear", __func__);
> +
> +		/* if the controller reset bit did clear, then set clock regs */
I have some confusion at this point. you added the above error message "Reset bits didn't clear".
But this comment is "if the controller reset bit did clear..".

I think that dev_err message would be better to locate into "if (!(mci_read(host, CTRL) & ...)".

> +		if (!(mci_readl(host, CTRL) & SDMMC_CTRL_RESET))
> +			goto ciu_out;
> +	}
> +
> +	if (IS_ENABLED(CONFIG_MMC_DW_IDMAC))
> +		/* It is also recommended that we reset and reprogram idmac */
> +		dw_mci_idmac_reset(host);
> +
> +	ret = true;
> +
> +ciu_out:
> +	/* After a CTRL reset we need to have CIU set clock registers  */
> +	mci_send_cmd(host->cur_slot, SDMMC_CMD_UPD_CLK, 0);
> +
> +	return ret;
>  }
>  
>  #ifdef CONFIG_OF
> @@ -2432,6 +2471,7 @@ int dw_mci_probe(struct dw_mci *host)
>  	const struct dw_mci_drv_data *drv_data = host->drv_data;
>  	int width, i, ret = 0;
>  	u32 fifo_size;
> +	u32 flags;
>  	int init_slots = 0;
>  
>  	if (!host->pdata) {
> @@ -2555,7 +2595,8 @@ int dw_mci_probe(struct dw_mci *host)
>  	}
>  
>  	/* Reset all blocks */
> -	if (!dw_mci_ctrl_all_reset(host))
> +	flags = SDMMC_CTRL_RESET | SDMMC_CTRL_FIFO_RESET | SDMMC_CTRL_DMA_RESET;
how about adding the SDMMC_CTRL_ALL_RESET macro into header file?
#define SDMMC_CTRL_ALL_RESET (.....)

> +	if (!dw_mci_ctrl_reset(host, flags))
>  		return -ENODEV;
>  
>  	host->dma_ops = host->pdata->dma_ops;
> @@ -2744,7 +2785,7 @@ int dw_mci_resume(struct dw_mci *host)
>  		}
>  	}
>  
> -	if (!dw_mci_ctrl_all_reset(host)) {
> +	if (!dw_mci_reset(host)) {
>  		ret = -ENODEV;
>  		return ret;
>  	}
> diff --git a/drivers/mmc/host/dw_mmc.h b/drivers/mmc/host/dw_mmc.h
> index 6bf24ab..2505804 100644
> --- a/drivers/mmc/host/dw_mmc.h
> +++ b/drivers/mmc/host/dw_mmc.h
> @@ -129,6 +129,7 @@
>  #define SDMMC_CMD_INDX(n)		((n) & 0x1F)
>  /* Status register defines */
>  #define SDMMC_GET_FCNT(x)		(((x)>>17) & 0x1FFF)
> +#define SDMMC_STATUS_DMA_REQ		BIT(31)
>  /* FIFOTH register defines */
>  #define SDMMC_SET_FIFOTH(m, r, t)	(((m) & 0x7) << 28 | \
>  					 ((r) & 0xFFF) << 16 | \
>