Re: Sandisk MMC I/O errors

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2014-08-06 16:21 GMT+02:00 Jean-Michel Hautbois
<jean-michel.hautbois@xxxxxxxxxxx>:
> 2014-08-06 15:37 GMT+02:00 Fabio Estevam <festevam@xxxxxxxxx>:
>> On Wed, Aug 6, 2014 at 10:27 AM, Jean-Michel Hautbois
>> <jean-michel.hautbois@xxxxxxxxxxx> wrote:
>>> 2014-08-06 13:44 GMT+02:00 Jaehoon Chung <jh80.chung@xxxxxxxxxxx>:
>>>> Hi,
>>>
>>> Hi Jaehoon,
>>>
>>>> In my case, -84 error is related with timing.
>>>> I recommend to check your clock source or pin strength.

I have dumped /sys/kernel/debug/mmc1/ios in both kernel releases.

In the current kernel (3.16) :
$> cat /sys/kernel/debug/mmc1/ios
clock:          52000000 Hz
actual clock:   49500000 Hz
vdd:            21 (3.3 ~ 3.4 V)
bus mode:       2 (push-pull)
chip select:    0 (don't care)
power mode:     2 (on)
bus width:      3 (8 bits)
timing spec:    8 (mmc DDR52)
signal voltage: 0 (3.30 V)

In the Freescale kernel (3.10.17) :
$> cat /sys/kernel/debug/mmc1/ios
clock:          52000000 Hz
actual clock:   49500000 Hz
vdd:            7 (1.65 - 1.95 V)
bus mode:       2 (push-pull)
chip select:    0 (don't care)
power mode:     2 (on)
bus width:      3 (8 bits)
timing spec:    7 (sd uhs DDR50)
signal voltage: 0 (3.30 V)

As you can see, there is at least too differences : VDD is not the
same I don't know why yet, and neither is timing spec. This seems to
be the real cause...
Investigating now, but any advice is interesting ! :)

Thanks,
JM
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