mmc: sdhci: remove mdelay in eMMC tuning
mmc: sdhci: remove mdelay in eMMC tuning

This patch removes an unneccesary 1ms mdelay in the HS200 tuning
loop, called 40 times per retuning. Currently this causes a latency
of >40ms on any emmc accesses triggering wake from runtime PM,
which can occur for a significant portion of reads on a mostly idle system.

The delay is left in place for SD Cards, which use
MMC_SEND_TUNING_BLOCK rather than MMC_SEND_TUNING_BLOCK_HS200.
I'm not able to find evidence that this is required for SD in the
specs I have access to, however this delay has been present from
initial checkin for SD so I have preserved the original behavior for
compatibility.

This has been verified to fix observed glitching on local audio
playback and recording on apps with inbuilt assumptions on storage
latency.

Signed-off-by: Nick Sanders <f4566bb3c90c0bf5fa0906b296b1da45051a62ee@chromium.org>
Reviewed-by: Grant Grundler <fd58b8293aeebb072b32124aef6e8da71dd5739c@chromium.org>
Reviewed-by: Doug Anderson <49983c4a76b998672954ed5edf4a62db4a336502@chromium.org>
Acked-by: Ulf Hansson <fe47b31f388f85ce6ddf64bf3a0cf6b46077d0e6@linaro.org>
Signed-off-by: Chris Ball <711c73f64afdce07b7e38039a96d2224209e9a6c@printf.net>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs