[U-Boot] [PATCH v2 1/3] ARM: Tegra: FDT: Add USB EHCI function for T30/T114

[Thierry Reding <thierry.reding@gmail.com>]

On Mon, Jun 17, 2013 at 10:39:12PM +0200, Marek Vasut wrote:
> Dear Thierry Reding,
> 
> > On Sun, Jun 16, 2013 at 10:48:45PM +0200, Marek Vasut wrote:
> > > Dear Thierry Reding,
> > > 
> > > > On Sat, Jun 15, 2013 at 11:28:25PM +0200, Marek Vasut wrote:
> > > > > Dear Thierry Reding,
> > > > > 
> > > > > > On Fri, Jun 14, 2013 at 06:41:40PM +0800, Jim Lin wrote:
> > > > > > [...]
> > > > > > 
> > > > > > > diff --git a/board/nvidia/dts/tegra30-beaver.dts
> > > > > > > b/board/nvidia/dts/tegra30-beaver.dts
> > > > > > 
> > > > > > [...]
> > > > > > 
> > > > > > > @@ -68,4 +69,9 @@
> > > > > > > 
> > > > > > >  		status = "okay";
> > > > > > >  		bus-width = <8>;
> > > > > > >  	
> > > > > > >  	};
> > > > > > > 
> > > > > > > +
> > > > > > > +	usb at 7d008000 {
> > > > > > > +		nvidia,vbus-gpio = <&gpio 61 3>; /* PH5,
> > > 
> > > USB13_VBUS_PULLUP */
> > > 
> > > > > > This doesn't work for me on Beaver. I need to turn the above line
> > > > > > into
> > > > > > 
> > > > > > this:
> > > > > > 	nvidia,vbus-gpio = <&gpio 236 0>; /* PDD4 */
> > > > > > 
> > > > > > PDD4 is the correct GPIO according to the schematics and the pin is
> > > > > > high-active. Also as far as I can tell, 3 is not a meaningful value
> > > > > > for the U-Boot GPIO bindings. Only the value 1 (low-active) is
> > > > > > used.
> > > > > > 
> > > > > > With that change applied on top of your patches I can see that a
> > > > > > USB flash drive connected to USB3 is indeed powered. However I
> > > > > > noticed
> > > > > > 
> > > > > > something strange. When I try to use USB, I get this:
> > > > > > 	Tegra30 (Beaver) # usb start
> > > > > > 	(Re)start USB...
> > > > > > 	USB0:   set_host_mode: GPIO 236 high
> > > > > > 	USB EHCI 1.00
> > > > > > 	scanning bus 0 for devices... 1 USB Device(s) found
> > > > > > 	
> > > > > > 	       scanning usb for storage devices... 0 Storage Device(s)
> > > > > > 	       found scanning usb for ethernet devices... 0 Ethernet
> > > > > > 	       Device(s) found
> > > > > > 
> > > > > > So no storage device is detected, even though a USB flash drive is
> > > > > > connected and powered properly. If I repeat the same command,
> > > > > > however,
> > > > > > 
> > > > > > the storage device is detected:
> > > > > > 	Tegra30 (Beaver) # usb reset
> > > > > > 	(Re)start USB...
> > > > > > 	USB0:   set_host_mode: GPIO 236 high
> > > > > > 	USB EHCI 1.00
> > > > > > 	scanning bus 0 for devices... 2 USB Device(s) found
> > > > > > 	
> > > > > > 	       scanning usb for storage devices... 1 Storage Device(s)
> > > > > > 	       found scanning usb for ethernet devices... 0 Ethernet
> > > > > > 	       Device(s) found
> > > > > > 
> > > > > > Any idea what might be going on here?
> > > > > 
> > > > > Try waiting a little after setting the GPIO maybe? The drive might
> > > > > need some time to settle.
> > > > 
> > > > I can make it work on the first invocation of "usb start" by adding a
> > > > rather long mdelay() at the very end of ehci_hcd_init() in the Tegra
> > > > EHCI driver. The magic value seems to be 853 ms. 852 ms wasn't enough
> > > > in any of the test runs. 853 ms always worked.
> > > > 
> > > > However 850+ ms seems like a very long time for the device to settle,
> > > > and keeping it in the driver probably isn't a good idea. Furthermore I
> > > > cannot reproduce the same issue with a newer flash drive, which works
> > > > fine with no additional delays.
> > > 
> > > Try reverting 020bbcb "usb: hub: Power-cycle on root-hub ports" ...
> > > there's a thread in the ML that it caused issues.
> > 
> > I reverted the following two patches:
> > 
> > 	0bf796f usb: hub: Parallelize power-cycling of root-hub ports
> > 	020bbcb usb: hub: Power-cycle on root-hub ports
> > 
> > because it wasn't trivial to revert only 020bbcb alone. However it
> > didn't change anything regarding the problem I was seeing.
> > 
> > Thierry
> 
> Ok, this looks ugly and calls for a bisect. Can you check it ? I'll try to test 
> if USB works for me on some EHCI-enabled device.

I should repeat that things work fine for a more recent flash drive, so
it doesn't look all that bad. Bisecting will be difficult because the
patches for Tegra30 haven't been merged upstream yet. Also I can't tell
for sure if this particular flash driver ever worked as expected since
I've never tried it before.

Given that I have limited time over the next few weeks, I'll see if I
can come up with a successful bisection. If I do I'll let you know.

Thierry
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