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Ignore RES (1 byte) if chip replied to REMS (2 bytes)

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SPI RES is the most unreliable way to identify chips because it only
returns a 1-byte ID for most chips.

For every given ID out there, probably a dozen incompatible flash
chips match it. We already refuse to identify a chip with RES if that
chip responds to RDID (3 bytes, good match), and with this patch we
additionally refuse RES if the chip responds to REMS (2 bytes, still a
good match). This increases matching accuracy a lot.

Besides that, the RDID/REMS response checking has been cleaned up for
better readability.

Corresponding to flashrom svn r899.

Signed-off-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006@gmx.net>
Acked-by: Sean Nelson <audiohacked@gmail.com>
This commit is contained in:
Carl-Daniel Hailfinger 2010-02-12 19:37:25 +00:00
parent fb0828f3db
commit e4edb067a6
1 changed files with 17 additions and 4 deletions
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21
spi.c
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@ -385,17 +385,30 @@ int probe_spi_res(struct flashchip *flash)
{
unsigned char readarr[3];
uint32_t id2;
const unsigned char allff[] = {0xff, 0xff, 0xff};
const unsigned char all00[] = {0x00, 0x00, 0x00};
/* Check if RDID was successful and did not return 0xff 0xff 0xff.
* In that case, RES is pointless.
/* Check if RDID is usable and does not return 0xff 0xff 0xff or
* 0x00 0x00 0x00. In that case, RES is pointless.
*/
if (!spi_rdid(readarr, 3) && ((readarr[0] != 0xff) ||
(readarr[1] != 0xff) || (readarr[2] != 0xff)))
if (!spi_rdid(readarr, 3) && memcmp(readarr, allff, 3) &&
memcmp(readarr, all00, 3)) {
msg_cdbg("Ignoring RES in favour of RDID.\n");
return 0;
}
/* Check if REMS is usable and does not return 0xff 0xff or
* 0x00 0x00. In that case, RES is pointless.
*/
if (!spi_rems(readarr) && memcmp(readarr, allff, JEDEC_REMS_INSIZE) &&
memcmp(readarr, all00, JEDEC_REMS_INSIZE)) {
msg_cdbg("Ignoring RES in favour of REMS.\n");
return 0;
}
if (spi_res(readarr))
return 0;
/* FIXME: Handle the case where RES gives a 2-byte response. */
id2 = readarr[0];
printf_debug("%s: id 0x%x\n", __func__, id2);
if (id2 != flash->model_id)