mmc: block: improve error recovery from command channel errors

Command channel errors fall into four classes:

1. The command was issued with the card in the wrong state
2. The command failed to be received by the card correctly
3. The cards response failed to be received by the host (CRC error)
4. The card failed to respond to the card

For (1), in theory we should know that the card is in the correct state.
However, a failed stop command (or other failure) may result in the card
remaining in a data transfer state from the previous command.  If we
detect this condition, we try to recover by sending a stop command.

For the initial commands (set block count and the read/write command)
no data will have been transferred.  All that we need deal with is
retrying at this point.  A failed stop command can be remedied as
above.

If we are unable to recover the card (eg, the card ignores our requests
for status, or we don't recognise the error code) then we immediately
fail the request.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Tested-by: Pawel Moll <pawel.moll@arm.com>
Signed-off-by: Chris Ball <cjb@laptop.org>

0 files changed, 0 insertions, 0 deletions