tree 961a177256e8227f7d71d29a0804c0e2bac3a92a
parent 9f7baebb39fa8c6331b42747ac5ffd8d9e27d594
author Marek Vasut <marek.vasut@gmail.com> 1585997105 +0200
committer Peng Fan <peng.fan@nxp.com> 1587559316 +0800

mmc: Add option to adjust b_max before long read

Add getter function which permits adjusting the maximum number of
blocks that could be read in a single sustained read transfer based
on the location of the source/target buffer and length, before such
transfer starts.

This is mainly useful on systems which have various DMA restrictions
for different memory locations, e.g. DMA limited to 32bit addresses,
and where a bounce buffer is used to work around such restrictions.
Since the U-Boot bounce buffer is mallocated, it's size is limited
by the malloc area size, and the read transfer to such a buffer must
also be limited. However, as not all areas are limited equally, the
b_max should be adjusted accordinly as needed to avoid degrading
performance unnecessarily.

Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
Cc: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Peng Fan <peng.fan@nxp.com>
Cc: Simon Glass <sjg@chromium.org>
Cc: Tom Rini <trini@konsulko.com>