On Wednesday, August 05, 2015 at 03:42:11 PM, Hans de Goede wrote: > Hi, > > On 05-08-15 03:19, Marek Vasut wrote: > > The code in question polls an USB port status via USB_REQ_GET_STATUS > > to determine whether there is a device on the port or not. The way to > > figure that out is to check two bits. Those are wPortChange[0] and > > wPortStatus[0]. > > > > The wPortChange[0] indicates whether some kind of a connection status > > change happened on a port (a device was plugged or unplugged). The > > wPortStatus[0] bit indicates the status of the connection (plugged or > > unplugged). > > > > The current code tests whether wPortChange[0] == wPortStatus[0] and > > if that's the case, considers the loop polling for the presence of a > > USB device on port finished. > > > > This works for most USB sticks, since they come up really quickly and > > trigger the USB port change detection before the first iteration of the > > detection loop happens. Thus, both wPortChange[0] and wPortStatus[0] > > are set to 1 and thus equal. The loop is existed in it's first iteration > > and the stick is detected correctly. > > > > The problem is with some obscure USB sticks, which take some time before > > they pop up on the bus after the port was enabled. In this case, both > > the wPortChange[0] and wPortStatus[0] are 0. They are equal again, so > > the loop again exits in the first iteration, but this is incorrect, as > > such USB stick didn't have the opportunity to get detected on the bus. > > > > Rework the code such, that it checks for wPortChange[0] first to test > > if any connection change happened at all. If no change occured, keep > > polling. If a change did occur, test the wPortStatus[0] to see there is > > some device present on the port and only if this is the case, break out > > of the polling loop. > > > > This patch also trims down the duration of the polling loop from 10s > > per port to 1s per port. This is still annoyingly long, but there is > > no better option in case of U-Boot unfortunatelly. This change will > > most likely increase the duration of 'usb start' on some platforms, > > but this is needed to fix a bug. > > > > Signed-off-by: Marek Vasut <[email protected]> > > Cc: Simon Glass <[email protected]> > > Cc: Hans de Goede <[email protected]> > > Looks good to me: > > Reviewed-by: Hans de Goede <[email protected]>
OK, let's apply it and see if anyone complains :) Thanks for checking it! _______________________________________________ U-Boot mailing list [email protected] http://lists.denx.de/mailman/listinfo/u-boot
