On Mon, Mar 19, 2018 at 03:40:48PM +0100, Greg Kroah-Hartman wrote: > On Mon, Mar 19, 2018 at 09:20:23AM -0500, Bin Liu wrote: > > On Sun, Mar 18, 2018 at 02:16:25PM +0100, Greg Kroah-Hartman wrote: > > > On Fri, Mar 16, 2018 at 02:09:51PM -0500, Bin Liu wrote: > > > > Hi, > > > > > > > > The kernel usb stack and musb drivers have gone through some changes in > > > > the past several kernel versions, such as adding otg fsm, musb runtime > > > > PM, and musb otg state moving from musb to musb->xceiv... I am wondering > > > > if the otg protocol (hnp, srp) functions are already broken in the musb > > > > drivers, but I don't have a platform to confirm it. > > > > > > > > Do we know by any chance there is still someone using the musb otg > > > > functions in any relatively newer kernel and we still need to support > > > > otg in musb? If not, I am thinking to clean up the otg functions in > > > > musb drivers to make the code easy to read and maintain. > > > > > > By "clean up" do you mean "delete it"? :) > > > > Yes, delete it to make the driver state machine simpler and use less > > flags for recording states. > > > > > > > > I don't know of any real OTG hardware that ever shipped, does anyone > > > else? > > > > > > > If we can make the conclusion to remove it, I propose the patch below > > > > to disable musb otg first, then clean up the driver later if nobody > > > > complains about the otg function removal. > > > > > > It will take years for people who make these types of devices to notice > > > that OTG is removed, so be careful about this. Refactor away, but > > > > I personally think we can safely say there wasn't any true OTG products > > where were under development in the last several years, but I am more > > concerned if there was any such product released in the past, for > > example omap24xx/34xx based, but was still actively maintained to the > > latest kernel? Then deleting OTG protocol from musb drivers would break > > them. > > Wasn't the BeagleBone devices using that chipset? If not, then you are No, BeagleBone uses TI AM335x devices which have two MUSB controllers, and released in around 2012. And I don't think anyone uses the true OTG on AM335x, but omap24xx/34xx devices are much older which I don't know the history... > probably fine. Sounds good. I will send a patch in a few weeks to disable OTG in musb for v3.18-rc1, too late for v4.17 now I think... Regards, -Bin. -- 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
