4.10-rc3 rpi issues

[Stefan Wahren]

Hi Michael,

> Michael Zoran <mzoran at crowfest.net> hat am 12. Januar 2017 um 01:26 geschrieben:
> 
> 
> On Wed, 2017-01-11 at 23:22 +0100, Stefan Wahren wrote:
> > Hi Michael,
> > 
> > > Michael Zoran <mzoran at crowfest.net> hat am 11. Januar 2017 um 22:38
> > > geschrieben:
> > > 
> > > 
> > > On Wed, 2017-01-11 at 16:46 +0000, Peter Robinson wrote:
> > > > On Wed, Jan 11, 2017 at 2:29 PM, Gerd Hoffmann <kraxel at redhat.com
> > > > >
> > > 
> > > I'm actually surprised that somebody hasn't tried to upstream the
> > > downstream USB driver which has less limitations.  The DWC USB
> > > controller is not Broadcom specific so it would apply to more then
> > > the
> > > RPI.  I would be interested in helping with such an effort and it
> > > may
> > > even be possibly to write the driver from "scratch".  The hardest
> > > part
> > > would be getting something like a PI Zero that doesn't have the USB
> > > hub
> > > soldered onto the board so that it's easy to attach a USB bus
> > > analyzer
> > > for better debugging.
> > 
> > This isn't a surprise. A new driver for a platform which is already
> > supported by a mainline driver won't be accepted. Maybe the dwc2
> > driver would have a better quality for bcm2835 if the Foundation
> > would use it instead of the separate downstream driver. Instead of
> > adding new driver it would be better to fix the existing one.
> 
> The two drivers have a different architecture.  The upstream driver
> submits all the I/O to the hardware at once and relies on the hardware
> sorting it out.  When the fixed number of slots are used, it just
> breaks.
> 
> The downstream driver attempts to schedule the I/O in software and
> submit it to the hardware piecemeal.

do you mean the microframe scheduler which is also available in dwc2 but disabled for bcm2835?