Hello, David. On Thu, Oct 19, 2017 at 01:30:34PM -0500, David Milburn wrote: > During hotplug, it is possible for 6Gbps link speed to > be limited all the way down to 1.5 Gbps which may lead > to a slower link speed when drive is re-connected. > > This behavior has been seen on a Intel Lewisburg SATA > controller (8086:a1d2) with HGST HUH728080ALE600 drive > where SATA link speed was limited to 1.5 Gbps and > when re-connected the link came up 3.0 Gbps. ata_dev_init > initializes link->spd to 0, but, the 0001 patch will > reset it once the link comes online. The 0002 patch will > allow the error handler to reset link->spd only if the > link is online; otherwise, it will always get set to 0. > > This patch set was retested on above configuration and > showed the hotplugged link to come back online at max > speed (6Gbps). I did not see the downgrade when testing > on Intel C600/X79, but retested patched linux-4.14-rc5 > kernel and didn't see any side effects from these > changes. Also, successfully retested hotplug on port > multiplier 3Gbps link. While the problem seems valid, I'm not sure the patches are in the right direction. Isn't the root cause the decision we're making in sata_down_spd_limit() where the code is explicitly choosing 1.5Gbps if spd information isn't available? It'd make more sense to make better decisions there rather than faking the information going into them. Thanks. -- tejun -- 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
