linux-kernel - Re: [PATCH] atmel-mci: Initialize BLKR before sending data transfer command

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Message-ID: <20081006194459.74ba0c84@mjolnir.drzeus.cx>
Date:	Mon, 6 Oct 2008 19:44:59 +0200
From:	Pierre Ossman <drzeus-list@...eus.cx>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	kernel@...32linux.org, Hein_Tibosch <hein_tibosch@...oo.es>,
	linux-kernel@...r.kernel.org,
	Haavard Skinnemoen <haavard.skinnemoen@...el.com>
Subject: Re: [PATCH] atmel-mci: Initialize BLKR before sending data transfer
 command

Linus, any chance of getting this into .27? It has been seen in the
wild and causes I/O errors (which can lead to data loss).

If so, you can add:

Signed-off-by: Pierre Ossman <drzeus@...eus.cx>

On Fri,  3 Oct 2008 17:07:38 +0200
Haavard Skinnemoen <haavard.skinnemoen@...el.com> wrote:

> The atmel-mci driver sometimes fails data transfers like this:
> 
>    mmcblk0: error -5 transferring data
>    end_request: I/O error, dev mmcblk0, sector 2749769
>    end_request: I/O error, dev mmcblk0, sector 2749777
> 
> It turns out that this might be caused by the BLKR register (which
> contains the block size and the number of blocks being transfered) being
> initialized too late. This patch moves the initialization of BLKR so
> that it contains the correct value before the block transfer command is
> sent.
> 
> This error is difficult to reproduce, but if you insert a long delay
> (mdelay(10) or thereabouts) between the calls to atmci_start_command()
> and atmci_submit_data(), all transfers seem to fail without this patch,
> while I haven't seen any failures with this patch.
> 
> Reported-by: Hein_Tibosch <hein_tibosch@...oo.es>
> Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@...el.com>
> ---
>  drivers/mmc/host/atmel-mci.c |    6 ++++--
>  1 files changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/mmc/host/atmel-mci.c b/drivers/mmc/host/atmel-mci.c
> index 917035e..0000896 100644
> --- a/drivers/mmc/host/atmel-mci.c
> +++ b/drivers/mmc/host/atmel-mci.c
> @@ -426,8 +426,6 @@ static u32 atmci_submit_data(struct mmc_host *mmc, struct mmc_data *data)
>  	host->sg = NULL;
>  	host->data = data;
>  
> -	mci_writel(host, BLKR, MCI_BCNT(data->blocks)
> -			| MCI_BLKLEN(data->blksz));
>  	dev_vdbg(&mmc->class_dev, "BLKR=0x%08x\n",
>  			MCI_BCNT(data->blocks) | MCI_BLKLEN(data->blksz));
>  
> @@ -483,6 +481,10 @@ static void atmci_request(struct mmc_host *mmc, struct mmc_request *mrq)
>  		if (data->blocks > 1 && data->blksz & 3)
>  			goto fail;
>  		atmci_set_timeout(host, data);
> +
> +		/* Must set block count/size before sending command */
> +		mci_writel(host, BLKR, MCI_BCNT(data->blocks)
> +				| MCI_BLKLEN(data->blksz));
>  	}
>  
>  	iflags = MCI_CMDRDY;


-- 
     -- Pierre Ossman

  Linux kernel, MMC maintainer        http://www.kernel.org
  rdesktop, core developer          http://www.rdesktop.org

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