linux-phytec-ti

mmc: host: omap_hsmmc: add software timer when timeout greater than hardware capablility

DRA7 Errata No i834: When using high speed HS200 and SDR104
cards, the functional clock for MMC module will be 192MHz.
At this frequency, the maximum obtainable timeout (DTO =0xE)
in hardware is (1/192MHz)*2^27 = 700ms. Commands taking longer
than 700ms will be affected by this small window frame and
will be timing out frequently even without a genune timeout
from the card. Workarround for this errata is use a software
timer instead of hardware timer to provide the delay requested
by the upper layer

So adding a software timer as a work around for the errata.
Instead of using software timeout only for larger delays requested
when using HS200/SDR104 cards which results in hardware and
software timer race conditions, so move all the timeout request
to use software timer when HS200/SDR104 card is connected and
use hardware timer when other type cards are connected.

Also start the software timer after queueing to DMA to ensure
we are more likely to expire within correct limits. To be ever
more sure that we won't expire this soft timer too early, we're
adding a 1000000ns slack to the data timeout requested by the
upper layer.

[rk@ti.com: fix compiler warning in sw timeout function and
use sw timeout for busy timeout]
Signed-off-by: Ravikumar Kattekola <rk@ti.com>
Signed-off-by: Mugunthan V N <mugunthanvnm@ti.com>
[kishon@ti.com: Fix the timeout value to account for the entire
transfer to complete here.]
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>