Re: [PATCH v6 3/4] usb: ehci: Add new EHCI driver for Broadcom STB SoC's

[Greg Kroah-Hartman]

On Thu, May 07, 2020 at 12:01:16AM +0300, Andy Shevchenko wrote:
> On Wed, May 6, 2020 at 11:23 PM Alan Cooper <alcooperx@xxxxxxxxx> wrote:
> > On Tue, May 5, 2020 at 7:00 AM Greg Kroah-Hartman
> > <gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
> > > On Thu, Apr 30, 2020 at 07:12:57AM -0400, Al Cooper wrote:
> 
> ...
> 
> > > > +     /* Hook the hub control routine to work around a bug */
> > >
> > > What bug?  This feels wrong.
> >
> > The bug is explained in a comment above the ehci_brcm_hub_control()
> > routine as follows:
> > /*
> >  * ehci_brcm_hub_control
> >  * Intercept echi-hcd request to complete RESUME and align it to the start
> >  * of the next microframe.
> >  * If RESUME is complete too late in the microframe, host controller
> >  * detects babble on suspended port and resets the port afterwards.
> >  * This s/w workaround allows to avoid this problem.
> >  * See SWLINUX-1909 for more details
> >  */
> > I'll remove the internal bug tracking reference from the comment.
> 
> I guess you may leave the internal bug reference. I can tell from my
> experience that's hard to understand what was going on in the driver
> in years perspective. It will help whoever in this company have a
> chance to look after the driver.

"internal bug references" mean nothing to the 99% of the people that can
see this.  Document the heck out of what this is instead please.

greg k-h