Date: Mon, 23 Jun 2008 17:04:49 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Andres Salomon <dilinger@queued.net>
Cc: drzeus-sdhci@drzeus.cx, sdhci-devel@list.drzeus.cx,
       linux-kernel@vger.kernel.org
Subject: Re: [PATCH] [OLPC] sdhci: add quirk for the Marvell CaFe's
 interrupt timeout
Message-Id: <20080623170449.6567d857.akpm@linux-foundation.org>
In-Reply-To: <20080623101352.3bbaf5b0@xo-debian>
References: <20080623101352.3bbaf5b0@xo-debian>
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On Mon, 23 Jun 2008 10:13:52 -0400
Andres Salomon <dilinger@queued.net> wrote:

> 
> The CaFe chip has a hardware bug that ends up with us getting a timeout
> value that's too small, causing the following sorts of problems:
> 
> [   60.525138] mmcblk0: error -110 transferring data
> [   60.531477] end_request: I/O error, dev mmcblk0, sector 1484353
> [   60.533371] Buffer I/O error on device mmcblk0p2, logical block 181632
> [   60.533371] lost page write due to I/O error on mmcblk0p2
> 
> Presumably this is an off-by-one error in the hardware.  Incrementing
> the timeout count value that we stuff into the TIMEOUT_CONTROL register
> gets us a value that works.  This bug was originally discovered by
> Pierre Ossman, I believe.
> 
> [thanks to Robert Millan for proving that this was still a problem]
> 
> Signed-off-by: Andres Salomon <dilinger@debian.org>
> ---
>  drivers/mmc/host/sdhci.c |   12 +++++++++++-
>  1 files changed, 11 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> index 5b74c8c..2b3f06a 100644
> --- a/drivers/mmc/host/sdhci.c
> +++ b/drivers/mmc/host/sdhci.c
> @@ -57,6 +57,8 @@ static unsigned int debug_quirks = 0;
>  #define SDHCI_QUIRK_RESET_AFTER_REQUEST			(1<<8)
>  /* Controller needs voltage and power writes to happen separately */
>  #define SDHCI_QUIRK_NO_SIMULT_VDD_AND_POWER		(1<<9)
> +/* Controller has an off-by-one issue with timeout value */
> +#define SDHCI_QUIRK_INCR_TIMEOUT_CONTROL		(1<<10)
>  
>  static const struct pci_device_id pci_ids[] __devinitdata = {
>  	{
> @@ -134,7 +136,8 @@ static const struct pci_device_id pci_ids[] __devinitdata = {
>  		.device         = PCI_DEVICE_ID_MARVELL_CAFE_SD,
>  		.subvendor      = PCI_ANY_ID,
>  		.subdevice      = PCI_ANY_ID,
> -		.driver_data    = SDHCI_QUIRK_NO_SIMULT_VDD_AND_POWER,
> +		.driver_data    = SDHCI_QUIRK_NO_SIMULT_VDD_AND_POWER |
> +				  SDHCI_QUIRK_INCR_TIMEOUT_CONTROL,
>  	},
>  
>  	{
> @@ -479,6 +482,13 @@ static void sdhci_prepare_data(struct sdhci_host *host, struct mmc_data *data)
>  			break;
>  	}
>  
> +	/*
> +	 * Compensate for an off-by-one error in the CaFe hardware; otherwise,
> +	 * a too-small count gives us interrupt timeouts.
> +	 */
> +	if ((host->chip->quirks & SDHCI_QUIRK_INCR_TIMEOUT_CONTROL))
> +		count++;
> +
>  	if (count >= 0xF) {
>  		printk(KERN_WARNING "%s: Too large timeout requested!\n",
>  			mmc_hostname(host->mmc));

This is needed in 2.6.26, I assume?

If so, I can merge it unless Pierre has objections?

And it will cause conflicts with overlapping changes in linux-next.

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