Hi Tom,
On Fri, May 11, 2012 at 1:14 PM, jimmzhang jimmzhang@nvidia.com wrote:
On Wed, 2012-05-09 at 10:34 -0700, Tom Warren wrote:
Simon Glass's proposal to fix this on Seaboard was NAK'd, so I removed his NS16550 references and added a small delay before SPI/UART muxing. Tested on my Seaboard with large SPI reads/writes and saw no corruption (crc's matched) and no spurious comm chars.\
I'm afraid this version does not work fully for me. The problem is I think that the UART gets zero bytes in it from when the SPI was active. This causes the next command to be ignored. So for example:
Tegra2 (SeaBoard) # echo fred fred Tegra2 (SeaBoard) # echo edmund edmund Tegra2 (SeaBoard) # saveenv Saving Environment to SPI Flash... Erasing SPI flash...Writing to SPI flash...done Tegra2 (SeaBoard) # echo blackadder
^^^^ this command does nothing!
Tegra2 (SeaBoard) # echo blackadder blackadder Tegra2 (SeaBoard) #
This is the reason why my original patch cleaned out the UART before reading further characters. If that logic really in impossible to have in U-Boot then the only option is (after a SPI operation) to read UART output using tstc() and getc() until there is nothing more. Ick.
That said, this is an improvement, since it allows SPI to work. So I am going to ack it so we can hopefully get it in there.
Acked-by: Simon Glass sjg@chromium.org
Signed-off-by: Tom Warren twarren@nvidia.com
Tested-by: Jimmy Zhang jimmzhang@nvidia.com
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Regards, Simon