Hi all,
The attached patch makes a (n admittedly not very pretty, but minimal)
change to powerpc/shared/flash/flash.c so that it won't try to erase a
flash segment just because the existing contents aren't all-1s. Now, so
long as no bits would have to be changed from a 0 to a 1 an erase is not
necessarily required.
With this change I've been able to use the spansionFlash driver to bring
up a JFFS2 file-system, reading and writing files, which failed without.
--
Nick Withers
Embedded Systems Programmer
Department of Nuclear Physics, Research School of Physics and Engineering
The Australian National University (CRICOS: 00120C)
>From f9672901b5e3a9a0d4982b3327a83415a0bdcaf5 Mon Sep 17 00:00:00 2001
From: Nick Withers <nick.with...@anu.edu.au>
Date: Fri, 17 Jan 2014 12:41:25 +1100
Subject: [PATCH] A flash erase cycle is not required unless a change of a bit
from a 0 to a 1 is requested
---
c/src/lib/libbsp/powerpc/shared/flash/flash.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/c/src/lib/libbsp/powerpc/shared/flash/flash.c b/c/src/lib/libbsp/powerpc/shared/flash/flash.c
index ebd38cf..4efd3a1 100644
--- a/c/src/lib/libbsp/powerpc/shared/flash/flash.c
+++ b/c/src/lib/libbsp/powerpc/shared/flash/flash.c
@@ -519,7 +519,7 @@ regionCheckAndErase(int bank, uint32_t offset, char *src, uint32_t n_bytes, int
struct bankdesc *b;
uint32_t i;
char *p;
-uint32_t a,e;
+uint32_t a,e;
if ( ! (b = argcheck(bank, offset, src, n_bytes)) )
return -1;
@@ -534,7 +534,8 @@ uint32_t a,e;
a += b->fblksz;
i = ( a > offset + n_bytes ) ? offset + n_bytes : a;
for ( p = (char*)(b->start + offset); p < (char*)(b->start + i); p++ ) {
- if ( (char)0xff != *p ) {
+ /* Check that there are no bits in *p that would need to be set, requiring an erase */
+ if ( ~(*p) & *(src + (p - ((char *) (b->start + offset)))) ) {
if ( ! quiet ) {
fprintf(stderr,"Starting offset not block-aligned and destination area not empty.\n");
fprintf(stderr,"I'll need to erase data below destination start\n");
@@ -548,7 +549,8 @@ uint32_t a,e;
e -= b->fblksz;
i = ( e < offset ) ? offset : e;
for ( p = (char*)(b->start + i); p < (char*)(b->start + offset + n_bytes); p++ ) {
- if ( (char)0xff != *p ) {
+ /* Check that there are no bits in *p that would need to be set, requiring an erase */
+ if ( ~(*p) & *(src + (p - ((char *) (b->start + i)))) ) {
if ( ! quiet ) {
fprintf(stderr,"Ending offset not block-aligned and destination area not empty.\n");
fprintf(stderr,"I'll need to erase data beyond destination end\n");
--
1.8.5.2
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