[MTD] m25p80: chip erase != block erase != sector erase

[Linux-MTD Mailing List]

Gitweb:     http://git.infradead.org/?p=mtd-2.6.git;a=commit;h=7854643a91eade84112dca9768eeb8d32463d101
Commit:     7854643a91eade84112dca9768eeb8d32463d101
Parent:     9168ab861ae3eb8942da61d884a5c1980ba98a5f
Author:     Chen Gong <g.chen at freescale.com>
AuthorDate: Wed Nov 26 10:23:57 2008 +0000
Committer:  David Woodhouse <David.Woodhouse at intel.com>
CommitDate: Wed Nov 26 10:24:27 2008 +0000

    [MTD] m25p80: chip erase != block erase != sector erase
    
    This fixes broken terminology added in the "m25p80.c erase enhance" patch,
    which added a chip erase command but called it "block erase".  There are
    already two block erase commands; blocks are 4KiB or 32KiB.  There's also
    a sector erase (usually 64 KiB).  Chip erase typically covers Megabytes.
    
      OPCODE_BE   ==> OPCODE_CHIP_ERASE
      erase_block ==> erase_chip
    
    [dbrownell at users.sourceforge.net: update sector erase comments too ]
    
    Signed-off-by: Chen Gong <clumsycg at gmail.com>
    Signed-off-by: David Brownell <dbrownell at users.sourceforge.net>
    Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
    Signed-off-by: David Woodhouse <David.Woodhouse at intel.com>
---
 drivers/mtd/devices/m25p80.c |   23 +++++++++++++----------
 1 files changed, 13 insertions(+), 10 deletions(-)

diff --git a/drivers/mtd/devices/m25p80.c b/drivers/mtd/devices/m25p80.c
index 6188fd4..6659b22 100644
--- a/drivers/mtd/devices/m25p80.c
+++ b/drivers/mtd/devices/m25p80.c
@@ -37,9 +37,9 @@
 #define	OPCODE_NORM_READ	0x03	/* Read data bytes (low frequency) */
 #define	OPCODE_FAST_READ	0x0b	/* Read data bytes (high frequency) */
 #define	OPCODE_PP		0x02	/* Page program (up to 256 bytes) */
-#define	OPCODE_BE_4K 		0x20	/* Erase 4KiB block */
+#define	OPCODE_BE_4K		0x20	/* Erase 4KiB block */
 #define	OPCODE_BE_32K		0x52	/* Erase 32KiB block */
-#define	OPCODE_BE		0xc7	/* Erase whole flash block */
+#define	OPCODE_CHIP_ERASE	0xc7	/* Erase whole flash chip */
 #define	OPCODE_SE		0xd8	/* Sector erase (usually 64KiB) */
 #define	OPCODE_RDID		0x9f	/* Read JEDEC ID */
 
@@ -167,7 +167,7 @@ static int wait_till_ready(struct m25p *flash)
  *
  * Returns 0 if successful, non-zero otherwise.
  */
-static int erase_block(struct m25p *flash)
+static int erase_chip(struct m25p *flash)
 {
 	DEBUG(MTD_DEBUG_LEVEL3, "%s: %s %dKiB\n",
 			flash->spi->dev.bus_id, __func__,
@@ -181,7 +181,7 @@ static int erase_block(struct m25p *flash)
 	write_enable(flash);
 
 	/* Set up command buffer. */
-	flash->command[0] = OPCODE_BE;
+	flash->command[0] = OPCODE_CHIP_ERASE;
 
 	spi_write(flash->spi, flash->command, 1);
 
@@ -250,15 +250,18 @@ static int m25p80_erase(struct mtd_info *mtd, struct erase_info *instr)
 
 	mutex_lock(&flash->lock);
 
-	/* REVISIT in some cases we could speed up erasing large regions
-	 * by using OPCODE_SE instead of OPCODE_BE_4K
-	 */
-
-	/* now erase those sectors */
-	if (len == flash->mtd.size && erase_block(flash)) {
+	/* whole-chip erase? */
+	if (len == flash->mtd.size && erase_chip(flash)) {
 		instr->state = MTD_ERASE_FAILED;
 		mutex_unlock(&flash->lock);
 		return -EIO;
+
+	/* REVISIT in some cases we could speed up erasing large regions
+	 * by using OPCODE_SE instead of OPCODE_BE_4K.  We may have set up
+	 * to use "small sector erase", but that's not always optimal.
+	 */
+
+	/* "sector"-at-a-time erase */
 	} else {
 		while (len) {
 			if (erase_sector(flash, addr)) {