cfi_cmdset_0002.c do_write_oneword(...) problem

[Todd Fischer]

Vlad,

I am also using the AMD L640DU chip (same internals as 641, just different
packaging).  The do_write_oneword() routine in cfi_cmdset_0002.c didn't work
for me.  I put in the following very ugly temporary patch to test where in
the code the problem was occurring.  This hack does allow JFFS2 / MTD to
work fine for me.  However, this hack is architecture specific (I am running
on an ARM7), so you may need to make appropriate changes for your
environment.  Also notice that I am not using the fast programming method
supported by the chip.  The purpose of the hack was to narrow down where in
the code it was failing, it is not a fix to the problem.

I have the added complexity that the ARM7 interrupt table is located in the
same flash part I am using for JFFS2, so I have to disable interrupts
whenever I put the flash chip in a non "read array" mode.  The
cfi_cmdset_0002.c code has many places where the flash chip is left if CFI
mode and erase-more-sectors mode, (thus hiding the interrupt vector table)
which I had to modify.  I hope there are no more silicon vendors dumb enough
to put interrupt vector tables in flash!


#if 1
	    /* short cut that works */
	{
	    volatile unsigned short *addr1;
	    unsigned short *block_addr;

	    addr1 = (unsigned short *)chip->start;
	    addr1[0x555] = 0xAA;
	    addr1[0x2aa] = 0x55;
	    addr1[0x555] = 0xA0;
	    block_addr = (unsigned short *)adr;
	    *block_addr = datum;
	}
#else
	    /* original code that looks like it should work, but doesn't */

	if (fast) { /* Unlock bypass */
		cfi_send_gen_cmd(0xA0, 0, chip->start, map, cfi, cfi->device_type, NULL);
	}
	else {
	        cfi_send_gen_cmd(0xAA, cfi->addr_unlock1, chip->start, map, cfi,
CFI_DEVICETYPE_X8, NULL);
	        cfi_send_gen_cmd(0x55, cfi->addr_unlock2, chip->start, map, cfi,
CFI_DEVICETYPE_X8, NULL);
	        cfi_send_gen_cmd(0xA0, cfi->addr_unlock1, chip->start, map, cfi,
CFI_DEVICETYPE_X8, NULL);
	}

	cfi_write(map, datum, adr);

#endif

You might try a similar change to see if your problem goes away.  If so, I
bet we are experiencing the same issue.

When I get to the bottom of what is causing the problem, I will let you know
what I found.

Todd Fischer
Cadenux
www.cadenux.com