Nikolai Zhubr a écrit : > Hello Matthieu, > > 09.01.2012 13:04, Matthieu CASTET wrote: >> Hi, >> >> I think there is a confusion : there 2 usb controller sold by Synopsys : >> >> - the one they buy from chip-idea (the ehci one extended to do otg and handle >> full-speed device without companion). This driver got more than one udc driver. >> >> - the one they did : DesignWare USB OTG. Most of the scheduling is done with >> software (at least for the version we had) : it make impossible to use full >> speed serial device on a high speed hub (irq storm due to split transaction). >> >> I think the driver of Nikolai is the second one. > > You are right. The irq problems you mentioned are reflected somewhere in > the code (Not that I understand it well). Does it mean successfull > connection just won't be possible in some cases? (Sorry if the question > sounds silly, my background wrt USB is still next to nonexistent) > What we saw was : on a product with a high speed hub : - plug a device that need a bulk transaction that is always resubmitted (for example a serial device) - the kernel freeze : it spends all of its time in the irq In our products with a hub, we forced full-speed for that reason. Matthieu -- 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
