[PATCH] mmc: sdhci-pltfm: Fix timeout on t4240's sdhci controller

[Gala Kumar-B11780]

On Mar 7, 2013, at 8:57 PM, Chunhe Lan wrote:

> On 03/08/2013 12:30 AM, Gala Kumar-B11780 wrote:
>> On Mar 7, 2013, at 2:05 AM, Chunhe Lan wrote:
>> 
>>> This patch fixes timeout problems on t4240's sdhci controller:
>>> 
>>> 	mmc0: Too large timeout requested for CMD25!
>>> 	mmc0: Too large timeout requested for CMD25!
>>> 	mmc0: Too large timeout requested for CMD25!
>>> 
>>> Signed-off-by: Chunhe Lan <Chunhe.Lan at freescale.com>
>>> ---
>>> drivers/mmc/host/sdhci-pltfm.c |    1 +
>>> 1 files changed, 1 insertions(+), 0 deletions(-)
>>> 
>>> diff --git a/drivers/mmc/host/sdhci-pltfm.c b/drivers/mmc/host/sdhci-pltfm.c
>>> index 3145a78..9db7b12 100644
>>> --- a/drivers/mmc/host/sdhci-pltfm.c
>>> +++ b/drivers/mmc/host/sdhci-pltfm.c
>>> @@ -94,6 +94,7 @@ void sdhci_get_of_property(struct platform_device *pdev)
>>> 
>>> 		if (of_device_is_compatible(np, "fsl,p2020-esdhc") ||
>>> 		    of_device_is_compatible(np, "fsl,p1010-esdhc") ||
>>> +		    of_device_is_compatible(np, "fsl,t4240-esdhc") ||
>>> 		    of_device_is_compatible(np, "fsl,mpc8536-esdhc"))
>>> 			host->quirks |= SDHCI_QUIRK_BROKEN_TIMEOUT_VAL;
>>> 
>>> -- 
>>> 1.7.6.5
>>> 
>> 
>> Why does this occur?  Is it a board issue?  Is it a silicon issue?  Is it due to some erratum?  Why T4 only?
>     It would be the property of T4 hardware, and please see below the patch which locates
>     the mail list of freescale:
> 
> eSDHC: mmc:host host need long time to generate command complete interrupt
> 
> According to Spec 2.0, command complete interrupt will generate within 150 SD-CLK.
> But this was not enough on T4240 board. So give it sufficient time to detect command
> timeout. 1000 * HZ will be enough, this value was test on all T4 board, all worked well.
> 
> Signed-off-by: Jerry Huang <Chang-Ming.Huang at freescale.com>
> Signed-off-by: Haijun Zhang <Haijun.Zhang at freescale.com>

I still don't understand the explanation of the issue on T4.  Why doesn't P4080, P5020, etc suffer from the issue?

- k