(OLD) (ARCHIVED) Puppy Linux Discussion Forum

[ozsouth]

From changelog of kernel 5.4.36 - shows why I only compile new kernels occasionally (apparently revert of revert):

commit 4fbf19bbba6a2f5a5aedcf9d98784fb3b5e8318b
Author: Alan S
Date: Wed Apr 22 16:13:08 2020 -0400

USB: hub: Revert commit bd0e6c9614b9 ("usb: hub: try old enumeration scheme first for high speed devices")

commit 3155f4f40811c5d7e3c686215051acf504e05565 upstream.

Commit bd0e6c9614b9 ("usb: hub: try old enumeration scheme first for high speed devices") changed the way the hub driver enumerates high-speed devices. Instead of using the "new" enumeration scheme first and switching to the "old" scheme if that doesn't work, we start with the "old" scheme. In theory this is better because the "old" scheme is slightly faster -- it involves resetting the device only once instead of twice.

However, for a long time Windows used only the "new" scheme. Zeng T said that Windows 8 and later use the "old" scheme for high-speed devices, but apparently there are some devices that don't like it. William B reports that the Ricoh webcam built into his Sony Vaio laptop not only doesn't enumerate under the "old" scheme, it gets hung up so badly that it won't then enumerate under the "new" scheme! Only a cold reset will fix it.

Therefore we will revert the commit and go back to trying the "new" scheme first for high-speed devices.

[8Geee]

I've seen this quite a bit in several series 4/5 kernels. While not modern, the 3.16.83 rev has fewer reverts, and infrequently updated.