[S] Change in flashrom[main]: erase/write: Deselect all smaller blocks when large block is selected

[Anastasia Klimchuk (Code Review)]

Anastasia Klimchuk has submitted this change. ( https://review.coreboot.org/c/flashrom/+/84686?usp=email )

(

3 is the latest approved patch-set.
No files were changed between the latest approved patch-set and the submitted one.
 )Change subject: erase/write: Deselect all smaller blocks when large block is selected
......................................................................

erase/write: Deselect all smaller blocks when large block is selected

Previously the logic which selected large block did deselect of
smaller blocks, but only one level below. So some even smaller blocks
could still remain selected, and this would result in duplicate erase.

This patch deselects all smaller blocks of all levels below, down to
the smallest size. If the area is covered by one large block, no
other smaller blocks inside are needed.

Change-Id: Icfc18d5c090b1dcb92ab157e2c139be71af59300
Spotted-by: persmule 
Signed-off-by: Anastasia Klimchuk 
Co-authored-by: persmule 
Reviewed-on: https://review.coreboot.org/c/flashrom/+/84686
Reviewed-by: Peter Marheine 
Tested-by: build bot (Jenkins) 
---
M erasure_layout.c
1 file changed, 31 insertions(+), 2 deletions(-)

Approvals:
  Peter Marheine: Looks good to me, approved
  build bot (Jenkins): Verified

diff --git a/erasure_layout.c b/erasure_layout.c
index 56841ab..7f3bb46 100644
--- a/erasure_layout.c
+++ b/erasure_layout.c
@@ -189,6 +189,27 @@
    }
 }

+/* Deselect all the blocks from index_to_deselect and down to the smallest. */
+static void deselect_erase_functions(const struct erase_layout *layout, size_t index_to_deselect,
+					int sub_block_start, const int sub_block_end)
+{
+	for (int j = sub_block_start; j <= sub_block_end; j++)
+		layout[index_to_deselect].layout_list[j].selected = false;
+
+	int block_start_to_deselect =
+		layout[index_to_deselect].layout_list[sub_block_start].first_sub_block_index;
+	int block_end_to_deselect =
+		layout[index_to_deselect].layout_list[sub_block_end].last_sub_block_index;
+
+	if (index_to_deselect)
+		deselect_erase_functions(layout,
+					index_to_deselect - 1,
+					block_start_to_deselect,
+					block_end_to_deselect);
+	else
+		return; // index_to_deselect has already reached 0, the smallest size of block. we are done.
+}
+
 /*
  * @brief	Function to select the list of sectors that need erasing
  *
@@ -229,9 +250,17 @@

const int total_blocks = sub_block_end - sub_block_start + 1;
    	if (count == total_blocks) {
+			/* We are selecting one large block instead, so send opcode once
+			 * instead of sending many smaller ones.
+			 */
    		if (ll->start_addr >= rstart && ll->end_addr <= rend) {
-				for (int j = sub_block_start; j <= sub_block_end; j++)
-					layout[findex - 1].layout_list[j].selected = false;
+				/* Deselect all smaller blocks covering the same region. */
+				deselect_erase_functions(layout,
+							findex - 1,
+							sub_block_start,
+							sub_block_end);
+
+				/* Select large block. */
    			ll->selected = true;
    		}
    	}