Stefan,
On 15-07-16 10:57, Olliver Schinagl wrote:
On 15-07-16 10:39, [email protected] wrote:
Hi Olliver,
Why are you using nRST signal?
What I mean is this pin is inactive on this eMMC chip. To use the signal
byte 162 of ECSD registers should be written.
Then that sounds like a bug in the mmc layer I would say (or a missing
attribute in the dts), we have a nRST signal it is wired, if the chip
ignores it, then nothing lost, if the chip needs to be initialized
with byte 162 of the ECSD register to make the nRST work, then that it
sounds like it should be fixed there?
By ommitting the nRST signal just because the chip isn't properly
initialized sounds more like a work-around to me, but I could be wrong
and see things wrong.
I just did a quick google query, and found the following post [0]. And
it appears it's a fuse in the eMMC chip to enable/disable this
functionality. I guess, but not sure, that our mmc driver in
u-boot/kernel does not use the reset flag properly (always high) if that
fuse has been enabled. I can imagine when using older u-boots this flag
isn't enabled, the fuse is not triggered yet and the pin is thus ignored?
What do the mmc guys, who have far more experience here, say?
On my board, this "reset" signal causes eMMC not to work.
That supprises me, as afaik I was using it just fine...
Olliver
Best regards,
Stefan Mavrodiev
[0]
https://groups.google.com/forum/#!category-topic/beagleboard/u-boot/1XwSNdZii1Y
--
Met vriendelijke groeten, Kind regards, 与亲切的问候
Olliver Schinagl
Software Engineer
Research & Development
Ultimaker B.V.
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