cfi_cmdset_0001.c: Excessive erase suspends
Joakim Tjernlund
Joakim.Tjernlund at transmode.se
Sat Apr 19 05:18:11 EDT 2008
> -----Original Message-----
> From: linux-mtd-bounces at lists.infradead.org [mailto:linux-mtd-bounces at lists.infradead.org] On Behalf
> Of Anders Grafström
> Sent: den 19 april 2008 00:11
> To: Jared Hulbert; Alexey Korolev; Linux-MTD Mailing List
> Subject: Re: cfi_cmdset_0001.c: Excessive erase suspends
>
> Jared Hulbert wrote:
> > 2) Did you check that the MTD is configured to treat this flash with
> > the correct bus width? I've been burned trying to figure out why a
> > 16bit configuration was missing half the data, turned out I had it
> > configured for 32bit MTD accesses.
>
> I think I got it right.
>
> > 3) I'd like to see that you can't use flash_eraseall and hexdump
> > /dev/mtdX to see this behavior. Or maybe you could try to create a
> > simple test that would suspend an erase 10K times and verify the erase
>
> See below.
>
> > A solution might be an small delay before a
> > write suspends the erase.
>
> udelay(100) right before the suspend command seems to work for me.
> It reduces the suspend count to about 1700 and no errors reported
> by JFFS2.
>
>
> I ran this routine in a standalone test program from u-boot:
>
> void test_flash_erase_suspend(void)
> {
> volatile unsigned int *flash = (unsigned int *)0x41040000;
> unsigned int i;
> unsigned int suspends = 0;
> unsigned int words = 10;
>
> /* Make sure there's something to erase */
> for (i = 0; i < 0x10000; i++) {
> if (flash[i] == 0xffffffff) {
> flash[i] = 0x00400040;
> flash[i] = 0;
> while ((flash[i] & 0x00800080) != 0x00800080);
> }
> }
>
> /* Clear status */
> flash[0] = 0x00500050;
>
> /* Erase */
> flash[0] = 0x00200020;
> flash[0] = 0x00d000d0;
>
> while (1) {
> /* Suspend */
> flash[0] = 0x00b000b0;
> suspends++;
>
> /* Short delay */
> for (i = 0; i < 1000; i++);
>
Don't you need to check that the chip is suspended before you do any
new operation?
> /* Resume */
> flash[0] = 0x00d000d0;
> flash[0] = 0x00700070;
>
> /* Erase done ? */
> if ((flash[i] & 0x00800080) == 0x00800080) {
> printf("\nStatus %08x\n", flash[i]);
> break;
> }
>
> /* Short delay */
> for (i = 0; i < 3500; i++);
> }
>
> /* Read array */
> flash[0] = 0x00ff00ff;
>
> /* Show the first 10 failed words */
> for (i = 0; i < 0x10000; i++) {
> if (flash[i] != 0xffffffff) {
> printf("%08x\n", flash[i]);
> if (--words == 0)
> break;
> }
> }
>
> printf("%d suspends\n", suspends);
> }
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