[flashrom] [PATCH] Use large reads for verify

[Carl-Daniel Hailfinger]

verify_range() and check_erased_range() check each page separately.
While that may have seemed like a good idea back when the code was
introduced, it has no benefits for any of the chips where we support
write because all of them handle cross-page reads nicely.
The only class of chips where this change could be a problem is chips
with non power of two sector sizes which have gaps in the address space.
We could simply require their read functions to provide gap-free results
and leave it at that.

This patch should speed up verify on Dediprog by a factor of ~100.

Signed-off-by: Carl-Daniel Hailfinger

Index: flashrom-verify_not_chunked/flashrom.c
===================================================================
--- flashrom-verify_not_chunked/flashrom.c	(Revision 1232)
+++ flashrom-verify_not_chunked/flashrom.c	(Arbeitskopie)
@@ -726,9 +726,8 @@
  */
 int verify_range(struct flashchip *flash, uint8_t *cmpbuf, int start, int len, char *message)
 {
-	int i, j, starthere, lenhere, ret = 0;
-	int page_size = flash->page_size;
-	uint8_t *readbuf = malloc(page_size);
+	int i, ret = 0;
+	uint8_t *readbuf = malloc(len);
    int failcount = 0;

if (!len)
@@ -753,37 +752,21 @@
    if (!message)
    	message = "VERIFY";
    
-	/* Warning: This loop has a very unusual condition and body.
-	 * The loop needs to go through each page with at least one affected
-	 * byte. The lowest page number is (start / page_size) since that
-	 * division rounds down. The highest page number we want is the page
-	 * where the last byte of the range lives. That last byte has the
-	 * address (start + len - 1), thus the highest page number is
-	 * (start + len - 1) / page_size. Since we want to include that last
-	 * page as well, the loop condition uses <=.
-	 */
-	for (i = start / page_size; i <= (start + len - 1) / page_size; i++) {
-		/* Byte position of the first byte in the range in this page. */
-		starthere = max(start, i * page_size);
-		/* Length of bytes in the range in this page. */
-		lenhere = min(start + len, (i + 1) * page_size) - starthere;
-		ret = flash->read(flash, readbuf, starthere, lenhere);
-		if (ret) {
-			msg_gerr("Verification impossible because read failed "
-				 "at 0x%x (len 0x%x)\n", starthere, lenhere);
-			break;
+	ret = flash->read(flash, readbuf, start, len);
+	if (ret) {
+		msg_gerr("Verification impossible because read failed "
+			 "at 0x%x (len 0x%x)\n", start, len);
+	}
+
+	for (i = 0; i < len; i++) {
+		if (cmpbuf[i] != readbuf[i]) {
+			/* Only print the first failure. */
+			if (!failcount++)
+				msg_cerr("%s FAILED at 0x%08x! "
+					 "Expected=0x%02x, Read=0x%02x,",
+					 message, start + i, cmpbuf[i],
+					 readbuf[i]);
    	}
-		for (j = 0; j < lenhere; j++) {
-			if (cmpbuf[starthere - start + j] != readbuf[j]) {
-				/* Only print the first failure. */
-				if (!failcount++)
-					msg_cerr("%s FAILED at 0x%08x! "
-						"Expected=0x%02x, Read=0x%02x,",
-						message, starthere + j,
-						cmpbuf[starthere - start + j],
-						readbuf[j]);
-			}
-		}
    }
    if (failcount) {
    	msg_cerr(" failed byte count from 0x%08x-0x%08x: 0x%x\n",