> >On Thu, Jan 9, 2020 at 5:39 PM Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> wrote: >> >> On Thu, Jan 09, 2020 at 08:34:12AM +0000, Pawel Laszczak wrote: >> > > >> > >On Thu, Jan 09, 2020 at 06:27:02AM +0000, Pawel Laszczak wrote: >> > >> >> + writel(EP_CMD_EPRST, &priv_dev->regs->ep_cmd); >> > >> >> + >> > >> >> + ret = readl_poll_timeout_atomic(&priv_dev->regs->ep_cmd, val, >> > >> >> + !(val & (EP_CMD_CSTALL | EP_CMD_EPRST)), >> > >> >> + 1, 1000); >> > >> >> + >> > >> >> + if (unlikely(ret)) >> > >> > >> > >> >Unless you can measure the difference of using/not using a >> > >> >unlikely/likely mark, NEVER use it. The compiler and cpu can almost >> > >> >always do better than you can, we have the tests to prove it. >> > >> > >> > >> >> > >> The both of the above timeout should never occur. If they occurred it would be a >> > >> critical controller bug. In this case driver can only inform about this event. >> > > >> > >"Should never occur" is a fun thing to say :) >> > > >> > >If it can never occur, then don't even check for it. >> > >> > Yes, on existing platforms it can never occur. >> > >> > > >> > >If it can, then check for it and handle it properly. >> > > >> > >What about this controller in systems with removable busses (like PCI?) >> > >What happens then (hint, I bet this could occur...) >> > >> > It's good question. Nobody from our customer currently use such system. >> > The only platform with PCI is used by me for testing purpose. >> >> So if you do have a PCI device, then you need to handle PCI reads >> failing and returning all 1s. Hopefully you can gracefully handle this :) >> >> Adding timeout handling here, where it is totally obvious to do so, >> would be a good thing. >> >> thanks, >> >> greg k-h > >Hi Pawel, > >My email is: peter.chen@xxxxxxx, please change it when your send next version. Hi Peter, I'm sorry for that. BTW. I need postpone sending the next version of this patch because there is some issue with synchronization of repositories regarding the patch "usb: cdns3: Add streams support to cadence USB3 DRD driver" I don't want generate new conflicts. Regards, Pawell > >Peter
