On Fri, 17 Oct 2014, Mark Knibbs wrote: > Hi, > > In include/linux/usb.h, there is > /* > * timeouts, in milliseconds, used for sending/receiving control messages > * they typically complete within a few frames (msec) after they're issued > * USB identifies 5 second timeouts, maybe more in a few cases, and a few > * slow devices (like some MGE Ellipse UPSes) actually push that limit. > */ > #define USB_CTRL_GET_TIMEOUT 5000 > #define USB_CTRL_SET_TIMEOUT 5000 Those timeout values are used with usb_control_msg(), which takes timeout values in milliseconds. > However several callers of usb_stor_control_msg() have timeout argument > specified as n*HZ, for example in drivers/usb/storage/transport.c: > > result = usb_stor_control_msg(us, us->send_ctrl_pipe, > USB_REQ_CLEAR_FEATURE, USB_RECIP_ENDPOINT, > USB_ENDPOINT_HALT, endp, > NULL, 0, 3*HZ); > > result = usb_stor_control_msg(us, us->recv_ctrl_pipe, > US_BULK_GET_MAX_LUN, > USB_DIR_IN | USB_TYPE_CLASS | > USB_RECIP_INTERFACE, > 0, us->ifnum, us->iobuf, 1, 10*HZ); > > result = usb_stor_control_msg(us, us->send_ctrl_pipe, > request, requesttype, value, index, data, size, > 5*HZ); This is because usb_stor_control_msg accepts timeout values in jiffies. > I'm just wondering whether those callers should have timeouts in ms (so > 3*HZ -> 3000), or whether the definitions of USB_CTRL_GET/SET_TIMEOUT > should be 5*HZ? Or is HZ always 1000 these days? No, no, and no. Alan Stern -- 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
