cfi_cmdset_0001.c: Excessive erase suspends
Joakim Tjernlund
Joakim.Tjernlund at transmode.se
Sat Apr 19 13:01:20 EDT 2008
> -----Original Message-----
> From: Anders Grafström [mailto:grfstrm at users.sourceforge.net]
> Sent: den 19 april 2008 15:47
> To: Joakim Tjernlund; 'Jared Hulbert'; 'Alexey Korolev'; 'Linux-MTD Mailing List'
> Subject: Re: cfi_cmdset_0001.c: Excessive erase suspends
>
> Joakim Tjernlund wrote:
> > Don't you need to check that the chip is suspended before you do any
> > new operation?
>
> You're right.
>
> Here's the improved version;
>
> static void erase_suspend(unsigned int loops)
> {
> volatile unsigned int *flash = (unsigned int *)0x41040000;
> unsigned int i;
> unsigned int suspends = 0;
> unsigned int words = 2;
> unsigned int timeout;
>
> /* 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;
> flash[0] = 0x00700070;
> timeout = 100000;
> while ((flash[0] & 0x00800080) != 0x00800080 && --timeout);
> if (!timeout)
> printf("suspend timeout\n");
> suspends++;
>
> /* Short delay */
> for (i = 0; i < 1000; i++);
>
> /* Resume */
> flash[0] = 0x00d000d0;
> flash[0] = 0x00700070;
>
> /* Erase done ? */
> if ((flash[0] & 0x00800080) == 0x00800080) {
> printf("\nstatus %08x\n", flash[0]);
> break;
> }
>
> /* Short delay */
> for (i = 0; i < loops; i++);
> }
>
> /* Read array */
> flash[0] = 0x00ff00ff;
>
> /* Show the first 2 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);
> }
>
> void test_flash_erase_suspend(void)
> {
> unsigned int loops;
>
> for (loops = 6000; loops > 2000; loops -= 500) {
> printf("\n%d loops", loops);
> erase_suspend(loops);
> }
> }
>
>
> It produced this output at one occasion:
>
> 6000 loops
> status 00800080
> ffff0000
> ffff0000
> 4783 suspends
>
> 5500 loops
> status 00800080
> 5508 suspends
>
> 5000 loops
> status 008000a0
> 6394 suspends
>
> 4500 loops
> status 00a000a0
> fffffeff
> fffffffe
> 5169 suspends
>
> 4000 loops
> status 00a000a0
> fffffeff
> fffffeff
> 5378 suspends
>
> 3500 loops
> status 00a000a0
> aaaaaaaa
> aaaaaaaa
> 5715 suspends
>
> 3000 loops
> status 00a000a0
> 55555555
> 55555555
> 6142 suspends
>
> 2500 loops
> status 00a000a0
> 00000000
> 00000000
> 6929 suspends
>
> It locks up when I drop it down to 2000 or less iterations in the loop between resume and suspend.
> I think I need to do more testing with properly timed delays.
>
> Is there anything else that I have missed?
Perhaps, you should make "i" a volatile. That said I know that Intel
had erase suspend bugs in their early strata flash, thats why there is
a define in cmdset_0001 that disables them.
Maybe you got buggy chips?
oh, just remembered, strata chips needs to have a stable address bus before
CS is pulled. We had add a small delay on CS in the memory controller, otherwise
they would fail, especially when cold.
>
> /Anders
>
More information about the linux-mtd
mailing list