Change in coreboot[master]: drivers/mrc_cache: Fix size comparison in mrc_cache update

[Tim Wawrzynczak (Code Review)]

Tim Wawrzynczak has uploaded this change for review. ( https://review.coreboot.org/c/coreboot/+/46824 )

Change subject: drivers/mrc_cache: Fix size comparison in mrc_cache update
......................................................................

drivers/mrc_cache: Fix size comparison in mrc_cache update

`mrc_cache_needs_update` is comparing the "new size" of the MRC data
(minus metadata size) to the size including the metadata, which causes
the driver to think the data has changed, and so it will rewrite the
MRC cache on every boot. This patch removes the metadata size from
the comparison.

BUG=b:171513942
BRANCH=volteer
TEST=1) Memory training data gets written the on a boot where the data
was wiped out.
2) Memory training data does not get written back on every subsequent
boot.

Signed-off-by: Tim Wawrzynczak 
Change-Id: I7280276f71fdaa492c327b2b7ade8e53e7c59f51
---
M src/drivers/mrc_cache/mrc_cache.c
1 file changed, 2 insertions(+), 2 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/24/46824/1

diff --git a/src/drivers/mrc_cache/mrc_cache.c b/src/drivers/mrc_cache/mrc_cache.c
index 3b98dba..eb43123 100644
--- a/src/drivers/mrc_cache/mrc_cache.c
+++ b/src/drivers/mrc_cache/mrc_cache.c
@@ -337,10 +337,10 @@
    			   const void *new_data, size_t new_data_size)
 {
    void *mapping, *data_mapping;
-	size_t size = region_device_sz(rdev);
+	size_t old_data_size = region_device_sz(rdev) - sizeof(struct mrc_metadata);
    bool need_update = false;

-	if (new_data_size != size)
+	if (new_data_size != old_data_size)
    	return true;

mapping = rdev_mmap_full(rdev);

[Shelley Chen (Code Review)]

Shelley Chen has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/46824 )

Change subject: drivers/mrc_cache: Fix size comparison in mrc_cache update
......................................................................

Patch Set 1: Code-Review+2

[Furquan Shaikh (Code Review)]

Furquan Shaikh has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/46824 )

Change subject: drivers/mrc_cache: Fix size comparison in mrc_cache update
......................................................................

Patch Set 1: Code-Review+2

[Patrick Georgi (Code Review)]

Patrick Georgi has submitted this change. ( https://review.coreboot.org/c/coreboot/+/46824 )

Change subject: drivers/mrc_cache: Fix size comparison in mrc_cache update
......................................................................

drivers/mrc_cache: Fix size comparison in mrc_cache update

`mrc_cache_needs_update` is comparing the "new size" of the MRC data
(minus metadata size) to the size including the metadata, which causes
the driver to think the data has changed, and so it will rewrite the
MRC cache on every boot. This patch removes the metadata size from
the comparison.

BUG=b:171513942
BRANCH=volteer
TEST=1) Memory training data gets written the on a boot where the data
was wiped out.
2) Memory training data does not get written back on every subsequent
boot.

Signed-off-by: Tim Wawrzynczak 
Change-Id: I7280276f71fdaa492c327b2b7ade8e53e7c59f51
Reviewed-on: https://review.coreboot.org/c/coreboot/+/46824
Tested-by: build bot (Jenkins) 
Reviewed-by: Shelley Chen 
Reviewed-by: Furquan Shaikh 
---
M src/drivers/mrc_cache/mrc_cache.c
1 file changed, 2 insertions(+), 2 deletions(-)

Approvals:
  build bot (Jenkins): Verified
  Furquan Shaikh: Looks good to me, approved
  Shelley Chen: Looks good to me, approved

diff --git a/src/drivers/mrc_cache/mrc_cache.c b/src/drivers/mrc_cache/mrc_cache.c
index 3b98dba..eb43123 100644
--- a/src/drivers/mrc_cache/mrc_cache.c
+++ b/src/drivers/mrc_cache/mrc_cache.c
@@ -337,10 +337,10 @@
    			   const void *new_data, size_t new_data_size)
 {
    void *mapping, *data_mapping;
-	size_t size = region_device_sz(rdev);
+	size_t old_data_size = region_device_sz(rdev) - sizeof(struct mrc_metadata);
    bool need_update = false;

-	if (new_data_size != size)
+	if (new_data_size != old_data_size)
    	return true;

mapping = rdev_mmap_full(rdev);