| Submitter | Carl-Daniel Hailfinger |
|---|---|
| Date | 2010-02-12 15:39:29 |
| Message ID | <4B757631.2030105@gmx.net> |
| Download | mbox | patch |
| Permalink | /patch/917/ |
| State | Accepted |
| Commit | r899 |
| Headers | show |
Comments
On 2/12/10 7:39 AM, Carl-Daniel Hailfinger wrote: > 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. > > Signed-off-by: Carl-Daniel Hailfinger<c-d.hailfinger.devel.2006@gmx.net> Acked-by: Sean Nelson <audiohacked@gmail.com>
On 12.02.2010 19:49, Sean Nelson wrote: > On 2/12/10 7:39 AM, Carl-Daniel Hailfinger wrote: >> 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. >> >> Signed-off-by: Carl-Daniel Hailfinger<c-d.hailfinger.devel.2006@gmx.net> > Acked-by: Sean Nelson <audiohacked@gmail.com> Thanks, committed in r899. Regards, Carl-Daniel
Patch
Index: flashrom-spi_res_avoidance/spi.c =================================================================== --- flashrom-spi_res_avoidance/spi.c (Revision 896) +++ flashrom-spi_res_avoidance/spi.c (Arbeitskopie) @@ -385,17 +385,30 @@ { 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)
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. Signed-off-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006@gmx.net>