Author: stefanct Date: Sat Feb 20 21:53:46 2016 New Revision: 1933 URL: http://flashrom.org/trac/flashrom/changeset/1933
Log: dediprog: tremendously improve performance on SF600 by ignoring the spec.
The solution was discovered in a collaborative bug hunt with testing done by David Hendricks. The actual culprit was found by Urja Rannikko by comparing vanilla flashrom with David's version in chromiumos.
Signed-off-by: Stefan Tauner stefan.tauner@alumni.tuwien.ac.at Tested-by: David Hendricks dhendrix@chromium.org Acked-by: Stefan Tauner stefan.tauner@alumni.tuwien.ac.at
Modified: trunk/dediprog.c
Modified: trunk/dediprog.c ============================================================================== --- trunk/dediprog.c Sat Feb 20 21:21:58 2016 (r1932) +++ trunk/dediprog.c Sat Feb 20 21:53:46 2016 (r1933) @@ -694,6 +694,14 @@ if (readcnt == 0) // If we don't require a response, we are done here return 0;
+ /* The specifications do state the possibility to set a timeout for transceive transactions. + * Apparently the "timeout" is a delay, and you can use long delays to accelerate writing - in case you + * can predict the time needed by the previous command or so (untested). In any case, using this + * "feature" to set sane-looking timouts for the read below will completely trash performance with + * SF600 and/or firmwares >= 6.0 while they seem to be benign on SF100 with firmwares <= 5.5.2. *shrug* + * + * The specification also uses only 0 in its examples, so the lesson to learn here: + * "Never trust the description of an interface in the documentation but use the example code and pray." const uint8_t read_timeout = 10 + readcnt/512; if (is_new_prot()) { idx = 0; @@ -703,6 +711,8 @@ value = min(read_timeout, 0xFF); // Possibly two bytes but we play safe here } ret = dediprog_read(CMD_TRANSCEIVE, value, idx, readarr, readcnt); + */ + ret = dediprog_read(CMD_TRANSCEIVE, 0, 0, readarr, readcnt); if (ret != readcnt) { msg_perr("Receive SPI failed, expected %i, got %i %s!\n", readcnt, ret, libusb_error_name(ret)); return 1;