tegra132: fix Rx FIFO underruns with slower SPI clock

The SPI controller operates on packets which can be variable
length up to 32-bit packets. It also has the ability to be
put in packed or unpacked mode w.r.t each packet. i.e. does
a single fifo register hold >= 1 packet. The current programming
uses 8-bit packets in unpacked mode which means 4 fifo slots
are used for a 32-bit DMA transfter. As the AHB can only operate
on a minimum of 32-bit bursts the triggers need to be programmed
correctly so that there is room for a full 32-bit DMA transaction.

Previously faster SPI clocks just made things magically work.

BUG=chrome-os-partner:30779
BRANCH=None
TEST=Built and booted through coreboot with 20MHz SPI clock.

Original-Change-Id: I3f1cd4dddcea9514327b2363ed450a527db7e1fe
Original-Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/208862
Original-Reviewed-by: Tom Warren <twarren@nvidia.com>
Original-Reviewed-by: Furquan Shaikh <furquan@chromium.org>
Original-Commit-Queue: Furquan Shaikh <furquan@chromium.org>
(cherry picked from commit d9864228a2479e412d7e0d2221fe536f78329acd)
Signed-off-by: Marc Jones <marc.jones@se-eng.com>

Change-Id: I61c145f35e1f889d4f83f3dfea049bfd347c1196
Reviewed-on: http://review.coreboot.org/8649
Tested-by: build bot (Jenkins)
Reviewed-by: Furquan Shaikh <furquan@google.com>

0 files changed, 0 insertions, 0 deletions