FROMLIST: mmc: sdhci: Optimize delay loops

The delay loops for reset and clock enable always take at least 1 ms
because they use mdelay(1). However they can take a lot less time e.g. less
than 50us. Use ktime and reduce the delay to 10 microseconds per loop.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
(am from https://patchwork.kernel.org/patch/9634743/)
Signed-off-by: Kevin Strasser <kevin.strasser@intel.com>

BUG=b:35774937
TEST=Check that max eMMC read latency on Cave/Caroline is under 30ms
TEST=`fio --name=trest --size=4k --readwrite=read`

Change-Id: Iedb13db830b10055fac57444c6fa912269fe95e3
Reviewed-on: https://chromium-review.googlesource.com/486956
Commit-Ready: Kevin Strasser <kevin.strasser@intel.com>
Tested-by: Russ Sage <russ.sage@intel.com>
Reviewed-by: Sonny Rao <sonnyrao@chromium.org>
(cherry picked from commit b7bf8e157faeca99a0670436ab3ea7f93c843962)
Reviewed-on: https://chromium-review.googlesource.com/506976
Tested-by: Sonny Rao <sonnyrao@chromium.org>
1 file changed