Patchwork [1/1] drivers/mtd/devices/m25p80.c: Fix whole device erase

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Submitter Cédric Cano
Date Sept. 21, 2012, 12:39 p.m.
Message ID <505C6017.8060607@ic.fr>
Download mbox | patch
Permalink /patch/185727/
State New
Headers show

Comments

Cédric Cano - Sept. 21, 2012, 12:39 p.m.
From: Cédric Cano<ccano@interfaceconcept.com>

When the whole SPI Flash is erased, the chip erase command is sent to the
device without waiting for end of erase. So next read/write accesses are
in failure.

This patch removes chip erase to use only sector per sector erase for
whole Flash too. When chip erase is done, Flash can be accessed without
error.

C. Cano

Signed-off-by: Cédric Cano<ccano@interfaceconcept.com>
---
  drivers/mtd/devices/m25p80.c |   50 +++++-------------------------------------
  1 file changed, 5 insertions(+), 45 deletions(-)
Artem Bityutskiy - Sept. 21, 2012, 1:42 p.m.
On Fri, 2012-09-21 at 14:39 +0200, Cédric Cano wrote:
> From: Cédric Cano<ccano@interfaceconcept.com>
> 
> When the whole SPI Flash is erased, the chip erase command is sent to the
> device without waiting for end of erase. So next read/write accesses are
> in failure.

Can you wait while the chip erase to finish?

> This patch removes chip erase to use only sector per sector erase for
> whole Flash too. When chip erase is done, Flash can be accessed without
> error.

How much slower is this method?

Patch

diff --git a/drivers/mtd/devices/m25p80.c b/drivers/mtd/devices/m25p80.c
index 5257345..b8956df 100644
--- a/drivers/mtd/devices/m25p80.c
+++ b/drivers/mtd/devices/m25p80.c
@@ -202,31 +202,6 @@  static int wait_till_ready(struct m25p *flash)
  	return 1;
  }
  
-/*
- * Erase the whole flash memory
- *
- * Returns 0 if successful, non-zero otherwise.
- */
-static int erase_chip(struct m25p *flash)
-{
-	pr_debug("%s: %s %lldKiB\n", dev_name(&flash->spi->dev), __func__,
-			(long long)(flash->mtd.size >> 10));
-
-	/* Wait until finished previous write command. */
-	if (wait_till_ready(flash))
-		return 1;
-
-	/* Send write enable, then erase commands. */
-	write_enable(flash);
-
-	/* Set up command buffer. */
-	flash->command[0] = OPCODE_CHIP_ERASE;
-
-	spi_write(flash->spi, flash->command, 1);
-
-	return 0;
-}
-
  static void m25p_addr2cmd(struct m25p *flash, unsigned int addr, u8 *cmd)
  {
  	/* opcode is in cmd[0] */
@@ -297,31 +272,16 @@  static int m25p80_erase(struct mtd_info *mtd, struct erase_info *instr)
  
  	mutex_lock(&flash->lock);
  
-	/* whole-chip erase? */
-	if (len == flash->mtd.size) {
-		if (erase_chip(flash)) {
+	/* "sector"-at-a-time erase */
+	while (len) {
+		if (erase_sector(flash, addr)) {
  			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)) {
-				instr->state = MTD_ERASE_FAILED;
-				mutex_unlock(&flash->lock);
-				return -EIO;
-			}
-
-			addr += mtd->erasesize;
-			len -= mtd->erasesize;
-		}
+		addr += mtd->erasesize;
+		len -= mtd->erasesize;
  	}
  
  	mutex_unlock(&flash->lock);