mtd: CFI cmdset_0002: enable erase-suspend-program

Erase-suspend for writing is required to avoid blocking applications
that wish to write some data (to a NOR block other than the one being
erased). Particularly, it solves some huge delays that an application
(which writes to a UBIFS) will experience if UBI attaches to empty NOR
flash. In this case the UBI background thread will erase a lot of blocks
and the application can be blocked for minutes because of the "MTD/CFI
chip lock".

This feature has been disabled for years. Maybe this was because the old
code turned it on for erase-suspend read-only chips also
(cfip->EraseSuspend & 0x1). This is wrong and corrected now.

This patch was tweaked by Norbert van Bolhuis.

Signed-off-by: Norbert van Bolhuis <nvbolhuis@aimvalley.nl>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

diff --git a/drivers/mtd/chips/cfi_cmdset_0002.c b/drivers/mtd/chips/cfi_cmdset_0002.c
index 94bb61e19047764ae06dcf91408946219869fa06..1d49e18adbf6f639d74b72e660b771c785b6397a 100644 (file)
--- a/drivers/mtd/chips/cfi_cmdset_0002.c
+++ b/drivers/mtd/chips/cfi_cmdset_0002.c
@@ -490,10 +490,6 @@ static struct mtd_info *cfi_amdstd_setup(struct mtd_info *mtd)
        }
 #endif
 
-       /* FIXME: erase-suspend-program is broken.  See
-          http://lists.infradead.org/pipermail/linux-mtd/2003-December/009001.html */
-       printk(KERN_NOTICE "cfi_cmdset_0002: Disabling erase-suspend-program due to code brokenness.\n");
-
        __module_get(THIS_MODULE);
        return mtd;
 
@@ -589,15 +585,9 @@ static int get_chip(struct map_info *map, struct flchip *chip, unsigned long adr
                return 0;
 
        case FL_ERASING:
-               if (mode == FL_WRITING) /* FIXME: Erase-suspend-program appears broken. */
-                       goto sleep;
-
-               if (!(   mode == FL_READY
-                     || mode == FL_POINT
-                     || !cfip
-                     || (mode == FL_WRITING && (cfip->EraseSuspend & 0x2))
-                     || (mode == FL_WRITING && (cfip->EraseSuspend & 0x1)
-                   )))
+               if (!cfip || !(cfip->EraseSuspend & (0x1|0x2)) ||
+                   !(mode == FL_READY || mode == FL_POINT ||
+                   (mode == FL_WRITING && (cfip->EraseSuspend & 0x2))))
                        goto sleep;
 
                /* We could check to see if we're trying to access the sector