On Tue, Dec 1, 2015 at 11:07 AM, Alan Stern <st...@rowland.harvard.edu> wrote: > On Tue, 1 Dec 2015, Oliver Neukum wrote: > >> On Tue, 2015-12-01 at 10:41 -0500, Alan Stern wrote: >> > > A recent patch, 7fa40910e0bf5ef32eca49595d950cb24f6402bf, added a >> > > CONNECTED retry for a different reason and I could simply increase >> > > this retry time. Any thoughts? >> > >> > I don't know. You've got a non-compliant host combined with an >> > excessively slow device. It seems unwise to penalize everybody by >> > slowing down their resumes (by 500 ms!) just because of this one >> > bad combination.
I'm now sure the host in "non-compliant". It looks like the USB-persist feature was created for the loss of "power session" on suspend/resume. Hibernate will usually remove power and it's just because the BIOS re-enables VBUS that PC's don't see this problem. Also there doesn't seem to be any spec for how long after VBUS a 2.0 (or 3.0) device should become CONNECTED. Most 2.0 or 3.0 hard drive based devices, either using a SATA to USB dongle or devices like the WD Passport take >500ms to set CONNECTED. I've tested many different 3.0 devices plugged into a 2.0 only port and all of them take longer than the 100ms currently needed to succeed. >> > >> > On the other hand, I don't have any better ideas. >> >> Yet another quirk. Assume this to be necessary only if the port >> was connected to a quirky device before loss of power. > > Yeah, okay. Although we have no way to know that the non-compliant > host controller turned off the port power. > > Alan, can you provide the vendor and product IDs for your USB-3 flash > drive? Or would you prefer to write a patch yourself? I think the best solution would be to use "wait_for_ss_port_enable()" (renamed) for 2.0 devices and not just 3.0 devices as discussed in: http://marc.info/?l=linux-usb&m=143768271119144&w=2 Al Cooper -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
