mmc: sdhci-msm: Set MMC_CAP_WAIT_WHILE_BUSY capability

For any cmd we have a DAT line timeouts which we set in TIMEOUT_CONTROL
register of sdhci. For commands with busy response (R1B), cmd is followed
by a busy period exercised by card, by pulling DAT0 line low
(in case of CMD5). Here host controller detects this busy period and
waits for either busy period to finish or timeout to happen based on
value set in SDHCI_TIMEOUT_CONTROL register.

Thus for R1B commands, host controller(sdhci) is capable of sending
two interrupts. 1st is the CMD response(0th bit -  Command complete
of Normal Interrupt Status register ) and 2nd is when the busy period has
ended(1st bit - Transfer Complete bit of Normal Interrupt Status register).

If MMC_CAP_WAIT_WHILE_BUSY is not enabled by the host controller driver
then core layer explictely waits for fixed amount time specified by
s_a_timeout parameter which is generally very high when compared to
amount of time card keeps the DAT0 line low.

As sdhci-msm is capable of detecting this busy period, set
MMC_CAP_WAIT_WHILE_BUSY capability in the host controller driver
to avoid redundant wait period.
On 8952 this saves us ~110ms during mmc suspend.

Change-Id: Ibb3a70575a06a5ffd1ccc3adaa96dfb3c3e22e3a
Signed-off-by: Ritesh Harjani <riteshh@codeaurora.org>

0 files changed, 0 insertions, 0 deletions