mmc: msm_sdcc: Reduce command timeouts and improve reliability.

Based on an original patch by Brent DeGraaf:

"Previous versions of the SD driver were beset with excessive command
timeouts. These timeouts were silent by default, but happened
frequently, especially during heavy system activity and concurrent
access of two or more SD devices. Worst case, these timeouts would
occasionally hit at the end of a successful write, resulting in false
failures that could adversely affect journaling file systems if timing
was unfortunate. This update tightens the association and timing between
dma transfers and the commands that trigger them by utilizing a new api
implemented in the datamover.  In addition, it also fixes a dma cache
coherency issue that was exposed during testing of this fix that
occasionally resulted in card corruption.  Processing of results in the
interrupt status routine was modified to process command results prior to
data because overwritten command results were observed during testing
since the data section can result in command issuances of its own.
This change also eliminates the software command timeout, relying entirely
on the hardware version, since the software timeout was found to cause
problems of its own after extensive testing (having hardware timer and
software timers addressing the same issue was found to cause a race
condition under heavy system load)."

This change originally added PROG_DONE handling, which has been split out
into a separate patch. Also on our platform, the data mover driver maintains
coherency to ensure API reliability, so the above mentioned cache corruption
issue was not an issue for us.

Signed-off-by: San Mehat <san@google.com>
Cc: Brian Swetland <swetland@google.com>

Change-Id: Ifbf17cfafb858106d73bf49af52b5161a265a484
Signed-off-by: San Mehat <san@google.com>
Signed-off-by: Daniel Walker <dwalker@codeaurora.org>

0 files changed, 0 insertions, 0 deletions