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ec/chromeec: fix LPC read/write for MEC devices 

Commit 8cf8aa2 [ec/google/chromeec: Use common MEC interface]
changed the return mechanism for the checksum on reads/writes
for MEC devices, but incorrectly handled the passed-in csum
parameter by not dereferencing. This led to the returned csum
value always being zero, which causes all EC commands with non-
NULL data_in to fail with a checksum error.

Fix this by storing the returned checksum in a temp variable,
and only assigning to csum when the pointer isn't NULL;

Test: build/boot google/chell, verify EC hello command succeeds,
keyboard backlight turned on at boot.

Change-Id: I7122c3fdc5a19f87f12975ee448728cf29948436
Signed-off-by: Matt DeVillier <matt.devillier@gmail.com>
Reviewed-on: https://review.coreboot.org/c/30444
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
This commit is contained in:
Matt DeVillier 2018-12-25 04:43:21 -06:00 committed by Patrick Georgi
parent 337afb0567
commit 680ed1f632
1 changed files with 6 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
src/ec/google/chromeec/ec_lpc.c
View File

@ -41,9 +41,11 @@ static void read_bytes(u16 port, unsigned int length, u8 *dest, u8 *csum)
#if IS_ENABLED(CONFIG_EC_GOOGLE_CHROMEEC_MEC)
/* Access desired range though EMI interface */
if (port >= MEC_EMI_RANGE_START && port <= MEC_EMI_RANGE_END) {
csum += mec_io_bytes(MEC_IO_READ, MEC_EMI_BASE,
u8 ret = mec_io_bytes(MEC_IO_READ, MEC_EMI_BASE,
port - MEC_EMI_RANGE_START,
dest, length);
if (csum)
*csum += ret;
return;
}
#endif
@ -78,9 +80,11 @@ static void write_bytes(u16 port, unsigned int length, u8 *msg, u8 *csum)
#if IS_ENABLED(CONFIG_EC_GOOGLE_CHROMEEC_MEC)
/* Access desired range though EMI interface */
if (port >= MEC_EMI_RANGE_START && port <= MEC_EMI_RANGE_END) {
csum += mec_io_bytes(MEC_IO_WRITE, MEC_EMI_BASE,
u8 ret = mec_io_bytes(MEC_IO_WRITE, MEC_EMI_BASE,
port - MEC_EMI_RANGE_START,
msg, length);
if (csum)
*csum += ret;
return;
}
#endif