On Mon, Jul 24, 2017 at 10:41:12AM -0400, Alan Stern wrote: > On Mon, 24 Jul 2017, Zdenek Kabelac wrote: > > > Hi > > > > I've problem with my USB storage devices: WD Elements 1TB. > > (Bus 004 Device 002: ID 1058:10a8 Western Digital Technologies, Inc. > > Elements > > Portable (WDBUZG)) > > > > > > After kernel >4.9 when disk is attached via cable it has very low speed > > (less then 1MB/s). > > > > It can run at full speed (>22MB/s) when the Linux kernel is fully rebooted > > (so > > disk is attached during the reboot of Lenovo T61, C2D, Fedora Rawhide). > > > > However when >4.9 kernel is running and disk is just attached it's very > > slow. > > > > I've played a bisect game - and the clean result has been: > > > > 22547c4cc4fe20698a6a85a55b8788859134b8e4 > > > > When I just revert this patch with 4.13-rc1 - it's again running with full > > speed even when disk is attached (thus no reboot is needed for full speed). > > > > > > So while I've no idea what 22547c4cc4fe20698... is doing, it seems to have > > some unpleasant side-effect on regular USB devices. > > > > So what else is needed to get this properly working ? > > (assuming plain revert of 22547c4cc4fe20698 is unwanted). > > > > What more info can I provide to get this storage 'normally' usable without > > rebooting the machine. > > Please post the dmesg logs showing what happens when the disk is > first attached and operates slowly, and what happens when the disk is > attached following a reboot and operates normally. >
Only idea I came up with is that some device may require more than one port reset. Agreed, dmesg logs should give us an idea if this is the case. I ordered one of those drives; maybe I can reproduce the problem. Guenter
