[U-Boot-Users] [patch] do not use cmd_reset uninitialized in cfi_flash.c

[Michael Schwingen]

> 
> Right. But it will be an improvement to the current implementation, where a 
> random command is written as RESET command. And also an improvement to the 
> fixed AMD/Intel RESET command. So I vote for trying this solution. I'll test 
> on a few of mine platforms too.
> 
> Michael, could please you provide a patch?

Okay - sorry, I did not have time for as much testing as I planned. 

>From a short test, it looks like AMD-style flash roms treat *any* unknown
command write as a reset, at least when in CFI Query mode, so issuing the
Intel reset command to AMD-style flashs seems safe (from the small sample I
have), plus the 3-cycle magic sequence should kick the state machine into
the right state even without a reset command. Since the AMD-style flashs
require the unlock sequence for real operation, I chose to try the AMD reset
command first, so that Intel flashs do no see an invalid command prior to
the CFI query.

I have tested the patch on AM29LV320-style flashs from Fujitsu and Macronix,
plus Intel StrataFlash.

cu
Michael


>From c18599658f8470898dc12ac99528d03b3a8d570c Mon Sep 17 00:00:00 2001
From: Michael Schwingen <michael at schwingen.org>
Date: Mon, 18 Feb 2008 23:04:17 +0100
Subject: [PATCH] do not use uninitialized cmd_reset; issue both AMD and Intel reset commands instead


Signed-off-by: Michael Schwingen <michael at schwingen.org>
---
 drivers/mtd/cfi_flash.c |    7 ++++++-
 1 files changed, 6 insertions(+), 1 deletions(-)

diff --git a/drivers/mtd/cfi_flash.c b/drivers/mtd/cfi_flash.c
index eb509f5..439c950 100644
--- a/drivers/mtd/cfi_flash.c
+++ b/drivers/mtd/cfi_flash.c
@@ -1538,7 +1538,12 @@ static int __flash_detect_cfi (flash_info_t * info, struct cfi_qry *qry)
 {
 	int cfi_offset;
 
-	flash_write_cmd (info, 0, 0, info->cmd_reset);
+	/* We do not yet know what kind of commandset to use, so we issue
+	   the reset command in both Intel and AMD variants, in the hope
+	   that AMD flash roms ignore the Intel command. */
+	flash_write_cmd (info, 0, 0, AMD_CMD_RESET);
+	flash_write_cmd (info, 0, 0, FLASH_CMD_RESET);
+
 	for (cfi_offset=0;
 	     cfi_offset < sizeof(flash_offset_cfi) / sizeof(uint);
 	     cfi_offset++) {
-- 
1.4.4.4