[commit] r1288 - trunk

[repository service]

Author: mkarcher
Date: Fri Apr 15 02:03:37 2011
New Revision: 1288
URL: http://flashrom.org/trac/flashrom/changeset/1288

Log:
Remove delays in JEDEC erase sequence

It is extremely unlikely that a chip not requiring delays in probe does
require them in erase. We observed unreliable erasing with a SST49LF004A
with these delays, so remove them if the are not required.

In review, I got the hint that "probe_jedec goes further by making that
call conditional on nonzero delay". I decided to ignore that. For
internal_delay, the small amount of clock cycles wasted for calling
programmer_delay(0) is negligible compared to LPC cycle times. It might
be an issue for 5 wasted bytes on the serial line in serprog. OTOH,
flash erase is still slow compared to 6*5 bytes on a serial port at
reasonable speed.

Signed-off-by: Michael Karcher 
Acked-by: Carl-Daniel Hailfinger

Modified:
   trunk/jedec.c

Modified: trunk/jedec.c
==============================================================================
--- trunk/jedec.c	Fri Apr 15 01:43:19 2011	(r1287)
+++ trunk/jedec.c	Fri Apr 15 02:03:37 2011	(r1288)
@@ -242,21 +242,24 @@
    		      unsigned int pagesize, unsigned int mask)
 {
    chipaddr bios = flash->virtual_memory;
+	int delay_us = 0;
+	if(flash->probe_timing != TIMING_ZERO)
+	        delay_us = 10;

/*  Issue the Sector Erase command   */
    chip_writeb(0xAA, bios + (0x5555 & mask));
-	programmer_delay(10);
+	programmer_delay(delay_us);
    chip_writeb(0x55, bios + (0x2AAA & mask));
-	programmer_delay(10);
+	programmer_delay(delay_us);
    chip_writeb(0x80, bios + (0x5555 & mask));
-	programmer_delay(10);
+	programmer_delay(delay_us);

chip_writeb(0xAA, bios + (0x5555 & mask));
-	programmer_delay(10);
+	programmer_delay(delay_us);
    chip_writeb(0x55, bios + (0x2AAA & mask));
-	programmer_delay(10);
+	programmer_delay(delay_us);
    chip_writeb(0x30, bios + page);
-	programmer_delay(10);
+	programmer_delay(delay_us);

/* wait for Toggle bit ready         */
    toggle_ready_jedec_slow(bios);
@@ -272,21 +275,24 @@
    		     unsigned int blocksize, unsigned int mask)
 {
    chipaddr bios = flash->virtual_memory;
+	int delay_us = 0;
+	if(flash->probe_timing != TIMING_ZERO)
+	        delay_us = 10;

/*  Issue the Sector Erase command   */
    chip_writeb(0xAA, bios + (0x5555 & mask));
-	programmer_delay(10);
+	programmer_delay(delay_us);
    chip_writeb(0x55, bios + (0x2AAA & mask));
-	programmer_delay(10);
+	programmer_delay(delay_us);
    chip_writeb(0x80, bios + (0x5555 & mask));
-	programmer_delay(10);
+	programmer_delay(delay_us);

chip_writeb(0xAA, bios + (0x5555 & mask));
-	programmer_delay(10);
+	programmer_delay(delay_us);
    chip_writeb(0x55, bios + (0x2AAA & mask));
-	programmer_delay(10);
+	programmer_delay(delay_us);
    chip_writeb(0x50, bios + block);
-	programmer_delay(10);
+	programmer_delay(delay_us);

/* wait for Toggle bit ready         */
    toggle_ready_jedec_slow(bios);
@@ -302,21 +308,24 @@
 {
    int total_size = flash->total_size * 1024;
    chipaddr bios = flash->virtual_memory;
+	int delay_us = 0;
+	if(flash->probe_timing != TIMING_ZERO)
+	        delay_us = 10;

/*  Issue the JEDEC Chip Erase command   */
    chip_writeb(0xAA, bios + (0x5555 & mask));
-	programmer_delay(10);
+	programmer_delay(delay_us);
    chip_writeb(0x55, bios + (0x2AAA & mask));
-	programmer_delay(10);
+	programmer_delay(delay_us);
    chip_writeb(0x80, bios + (0x5555 & mask));
-	programmer_delay(10);
+	programmer_delay(delay_us);

chip_writeb(0xAA, bios + (0x5555 & mask));
-	programmer_delay(10);
+	programmer_delay(delay_us);
    chip_writeb(0x55, bios + (0x2AAA & mask));
-	programmer_delay(10);
+	programmer_delay(delay_us);
    chip_writeb(0x10, bios + (0x5555 & mask));
-	programmer_delay(10);
+	programmer_delay(delay_us);

toggle_ready_jedec_slow(bios);