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: NRussell King <rmk+kernel@arm.linux.org.uk> Acked-by: NLinus Walleij <linus.walleij@linaro.org> Tested-by: NPawel Moll <pawel.moll@arm.com> Signed-off-by: NChris Ball <cjb@laptop.org>
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