Subject: [patch] cfi: prevent kernel panic with cfi flash

From: "Jan Pedersen" <[email-masked]>
Date: Tue, 27 Sep 2005 21:25:42 +0200

When using the cfi (common flash interface) driver, every word written to
the flash chips is followed by a operation complete poll. This poll is
intended to have a timeout of 1 ms. However this timeout is calculated by
HZ/1000, which happends to be 0 because HZ < 1000. The result of this is
that there will be just one poll for operation complete. If this single poll
fails, the kernel panics. This patch increases this timeout to HZ (1
second). This is far more than needed, but is preferred over a panic. This
fix is well tested and completely avoids the panic.

Signed-off-by: Jan Pedersen <[email-masked]>
---
diff -Naur linux-2.4.31.org/drivers/mtd/chips/cfi_cmdset_0002.c
linux-2.4.31/drivers/mtd/chips/cfi_cmdset_0002.c
--- linux-2.4.31.org/drivers/mtd/chips/cfi_cmdset_0002.c	2004-11-17
06:54:21.000000000 -0500
+++ linux-2.4.31/drivers/mtd/chips/cfi_cmdset_0002.c	2005-08-22
12:14:17.000000000 -0400
@@ -510,7 +510,7 @@
 	   or tells us why it failed. */        
 	dq6 = CMD(1<<6);
 	dq5 = CMD(1<<5);
-	timeo = jiffies + (HZ/1000); /* setting timeout to 1ms for now */
+	timeo = jiffies + (HZ); /* setting timeout to 1s for now */
 		
 	oldstatus = cfi_read(map, adr);
 	status = cfi_read(map, adr);

---

From: Ralf Baechle <[email-masked]>
Date: Fri, 30 Sep 2005 01:20:17 +0100

> Signed-off-by: Jan Pedersen <[email-masked]>

Patch looks good to me - but this code isn't maintained by linux-mips.org,
so you may want to resend your patches here:

MEMORY TECHNOLOGY DEVICES
P:      David Woodhouse
M:      [email-masked]
W:      http://www.linux-mtd.infradead.org/
L:      [email-masked]
S:      Maintained

Thanks anyway,

  Ralf