> From: Jingoo Han [mailto:jg1.han@xxxxxxxxxxx] > Sent: Monday, August 18, 2014 2:17 AM > > On Monday, August 18, 2014 5:32 PM, Peter Chen wrote: > > > > linux-2.6/drivers/usb/dwc2/gadget.c: In function 's3c_hsotg_irq_enumdone': > > linux-2.6/drivers/usb/dwc2/gadget.c:1904: warning: 'ep_mps' may be used uninitialized in this > function > > (+cc Dinh Nguyen) > > I think that this warning is false. > Because, 'ep_mps' cannot be used uninitialized in s3c_hsotg_irq_enumdone(). > > static void s3c_hsotg_irq_enumdone(struct s3c_hsotg *hsotg) > { > int ep0_mps = 0, ep_mps; > > case DSTS_ENUMSPD_FS: > case DSTS_ENUMSPD_FS48: > ep0_mps = EP0_MPS_LIMIT; > ep_mps = 1023; > break; > > case DSTS_ENUMSPD_HS: > ep0_mps = EP0_MPS_LIMIT; > ep_mps = 1024; > break; > > In the case of DSTS_ENUMSPD_FS, DSTS_ENUMSPD_FS48, and DSTS_ENUMSPD_HS, > both 'ep0_mps' and 'ep_mps' are initialized. > > case DSTS_ENUMSPD_LS: > hsotg->gadget.speed = USB_SPEED_LOW; > break; > > In the case of DSTS_ENUMSPD_LS, 'ep_mps' is uninitialized. > But, 'ep0_mps' is also '0'. > > ..... > > if (ep0_mps) { > int i; > s3c_hsotg_set_ep_maxpacket(hsotg, 0, ep0_mps); > for (i = 1; i < hsotg->num_of_eps; i++) > s3c_hsotg_set_ep_maxpacket(hsotg, i, ep_mps); > } > > If 'ep0_mps' is '0', 'ep_mps' will not be used. > So, uninitialized 'ep_mps' cannot be used. > > However, in the future, it is not sure that the current scheme > will not be modified. Thus, in order to make sure the code safety, > this patch may be necessary. But 0 is not a valid default value for an endpoint mps. So I think the patch serves no purpose other than to shut up the compiler. That's OK with me, but I think the usual kernel practice is not to add unnecessary initializations just to silence a compiler warning. -- Paul -- 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
