On 12/12/2013 08:14 PM, Paul Zimmerman wrote: >> From: linux-usb-owner@xxxxxxxxxxxxxxx [mailto:linux-usb-owner@xxxxxxxxxxxxxxx] On Behalf Of Robert Baldyga >> Sent: Thursday, December 12, 2013 12:51 AM >> >> This patch adds "maxpacket_limit" to struct usb_ep. This field contains >> maximum value of maxpacket supported by driver, and is set in driver probe. >> This value should be used by autoconfig() function, because value of field >> "maxpacket" is set to value from endpoint descriptor when endpoint becomes >> enabled. So when autoconfig() function will be called again for this endpoint, >> "maxpacket" value will contain wMaxPacketSize from descriptior instead of >> maximum packet size for this endpoint. > > Can you describe what the exact problem is that this patch is trying to > solve? Under what circumstances does the problem show up? And perhaps a > pointer to any previous email thread where this was discussed? Thanks. > Hello Paul, This problem shows up when you unload gadget which uses, for example, maxpacket=64 for its endpoints, and then you want to load gadget which want to use greater maxpacket value (for example maxpacket=512). In described case autoconfig() function will not be able to return endpoints used by previous gadget, because their "maxpacket" field is set to 64, and it seems to be maximum supported value. Using additional field "maxpacket_limit" to store original value set by UDC driver solves this problem, because autoconfig can see maximum packet value handled by endpoint irrespectively to "maxpacket" value used by previously loaded gadget. Best regards Robert Baldyga Samsung R&D Institute Poland -- 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
