[PATCH] mci: mmci: Fix read FIFO handling

[Sascha Hauer]

On Fri, Sep 02, 2016 at 10:50:37AM +0200, Michael Olbrich wrote:
> According to the Linux kernel and the qemu code, the MMCIFIFOCNT contains
> the remaining number of words to read, excluding those that are already in
> the FIFO. So the current number of bytes in the FIFO is
> host_remain - (readl(base + MMCIFIFOCNT) << 2).
> 
> Also writing to MMCIDATACTRL will reset the read counter. As a result,
> MCI_DATABLOCKEND is never set and read_bytes() waits forever.
> 
> With this change, SD-Card support on qemu vexpress works correctly.
> 
> Signed-off-by: Michael Olbrich <m.olbrich at pengutronix.de>
> ---
>  drivers/mci/mmci.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)

Applied, thanks

Sascha

> 
> diff --git a/drivers/mci/mmci.c b/drivers/mci/mmci.c
> index 9d1e858917de..7489ee03a13c 100644
> --- a/drivers/mci/mmci.c
> +++ b/drivers/mci/mmci.c
> @@ -212,7 +212,7 @@ static u64 mmci_pio_read(struct mmci_host *host, char *buffer, unsigned int host
>  	struct variant_data *variant = host->variant;
>  
>  	do {
> -		int count = readl(base + MMCIFIFOCNT) << 2;
> +		int count = host_remain - (readl(base + MMCIFIFOCNT) << 2);
>  
>  		if (count > host_remain)
>  			count = host_remain;
> @@ -264,7 +264,6 @@ static int read_bytes(struct mci_host *mci, char *dest, unsigned int blkcount, u
>  	dev_dbg(host->hw_dev, "read_bytes: blkcount=%u blksize=%u\n", blkcount, blksize);
>  
>  	do {
> -		mmci_writel(host, MMCIDATACTRL, mmci_readl(host, MMCIDATACTRL));
>  		len = mmci_pio_read(host, dest, xfercount);
>  		xfercount -= len;
>  		dest += len;
> -- 
> 2.9.3
> 
> 
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