tegra124: Rewrite SDRAM parameter saving code to be more efficient

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This patch overhauls the structure of the code that saves SDRAM
parameters to PMC registers for LP0 support, which had formerly been
very close to the U-Boot implementation. The new code keeps the
"translation table" entries as they are, but redefines the macros to
output hardcoded assignments instead of structure entries that need to
be parsed at runtime. It explicitly allows the compiler to merge and
reorder all accesses (under the assumption that PMC scratch registers
are essentially "like memory", without read or write side effects),
which generates much better and more importantly smaller code.

BUG=chrome-os-partner:25062
TEST=Nyan_big boots (on my Norrin, with the required board_id hacks) and
can suspend/resume fine to LP0. Measured (uncompressed) romstage size
for nyan_big at 25K without LP0 support, 43K with the old U-Boot style
implementation and 32K with this patch. Execution time of the function
drops from 1.2ms to .09ms.

Change-Id: Id52577c14d22ee67f167f10c3b976a037b1a321f
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/184388

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Julius Werner 2014-01-28 18:51:18 -08:00 • committed by chrome-internal-fetch

parent 7476b4bd0e

commit 25084bd040

1 changed files with 588 additions and 652 deletions

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src/soc/nvidia/tegra124/sdram_lp0.c

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