Am Dienstag, 26. Juli 2011, 08:46:07 schrieb Thomas Petazzoni: > Hello, > > Thanks again for the quick feedback. > > Le Mon, 25 Jul 2011 15:08:53 -0400 (EDT), > Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> a écrit : > > There's no contradiction. If 175 mA total are available, then one way > > to apportion it is to plug in a single device requiring 175 mA. In > > other words, there really is up to 175 mA available for each port. > > Hum, I'm sorry, but I still see a contradiction : > > * On one side, there is a computation that assumes that hdev->bus_mA > is a *per-port* current limit (and this computation is used to > reject new USB configurations from connecting) ; > > * On another side, there is a computation that assumes that > hdev->bus_mA is a *global hub* current limit (and this computation > is used to print a warning in the kernel messages). > > If I set a global current limit of 175 mA, then two devices of 100 mA > shouldn't be allowed to connect. I am afraid this is a true problem. We need to make the computation of the available power dynamic. The computation of hub->mA_per_port once is insufficient, as we cannot say that a limit valid for any port is valid for every port forever. The logical place for this dynamic adjustment would be usb_set_configuration() Regards Oliver - - - SUSE LINUX Products GmbH, GF: Jeff Hawn, Jennifer Guild, Felix Imendörffer, HRB 16746 (AG Nürnberg) Maxfeldstraße 5 90409 Nürnberg Germany - - - -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
