On Mon, 20 Oct 2008 01:40:21 +0200, Mikael Pettersson wrote: >On Mon, 13 Oct 2008 14:16:24 +0900, Tejun Heo wrote: >>Mikael Pettersson wrote: >>> - hardreset in sata_promise seems broken. I'll take a closer look >>> at that in about a week's time (I'll be busy with other work the >>> next couple of days). >> >>This looks like a rather serious problem, so please take a look at >>this. > >I've done more tests now, and the problem is that errors detected >outside of sata_promise itself, typically timeouts, don't trigger >the pdc_reset_port() call needed to bring the ATA engine behind the >port back to sanity. I did a round of regression tests which identified another related but different problem. In kernels 2.6.24 and 2.6.25 sata_promise would actually recover from the timeouts, while in kernels 2.6.26 and 2.6.27 it would not. Before 2.6.26 sata_promise explicitly used sata_std_hardreset, but in the "make reset related methods proper port operations" commit (a1efdaba2dbd6fb89e23a87b66d3f4dd92c9f5af), Tejun changed sata_promise to use the hardreset it now inherits from ata_sff_port_ops, namely sata_sff_hardreset. This change looks accidental. The main difference between these two procedures is that the sff version will poll the legacy status register until the port becomes ready. Changing sata_promise to use sata_std_hardreset in 2.6.26/.27 makes the EH after the timeouts much more reliable. Not as tidy as with the previous ->prereset fix, but still working. /Mikael -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
