Hi Everyone,
After the following patch from JJ, U-boot shifts to a lower speed mode from HS200 when accessing a boot partition.
01298da31d mmc: Change mode when switching to a boot partition
I have looked through the JESD84-B51 spec for eMMC card and don't see it say anywhere that boot0 partition cannot be accessed in HS200 modes.
In practice, I have seen timeouts sometimes when I try to write to the boot partition in HS200 mode on a dra7xx-evm in U-boot but not consistently (one would expect if such a thing was forbidden by the spec then it wouldn't work at all).
Can anyone point to a documentation that says that boot partition cannot be accessed in HS200 mode? Has anyone else observed failures before this patch?
I was able to access the boot0 partition in kernel in HS200 mode (log below). Unless there is code to fallback to a lower speed in kernel also (which doesn't seem to be the case from a simple searching of the code), this should prove that boot partitions can be accessed in HS200 speed mode.
Here is the log: https://pastebin.ubuntu.com/p/W3SB4N3rfn/
Thanks, Faiz