[U-Boot] [PATCH] ppc4xx: Canyonlands: Fix USB host PHY reset sequence

[David Mitchell]

Hi Wolfgang,

> -----Original Message-----
> From: Wolfgang Denk [mailto:wd at denx.de]
> Sent: Monday, December 14, 2009 2:42 PM
> To: David Mitchell
> Cc: u-boot at lists.denx.de; Stefan Roese; Jeff Mann
> Subject: Re: [U-Boot] [PATCH] ppc4xx: Canyonlands: Fix USB host PHY
> reset sequence
> 
> > -	/* Enable USB host & USB-OTG */
> > +	/* Enable USB host & USB-OTG;force assert,then de-assert PHY
> reset */
> > +	out_8((void *)CONFIG_SYS_BCSR_BASE + 7, 1);
> > +	mdelay(100);
> >  	out_8((void *)CONFIG_SYS_BCSR_BASE + 7, 0);
> > +	mdealy(100);
> 
> It would have been nice if you had at least tried to compile that.
> "mdealy()" is a typo, right?

Ah, sorry about that. I had the patch hanging around and moved it up to
the ToT by hand.

I'll fix and re-submit.

> 
> And do we really need 200 milliseconds delay?

I generated several versions for a remote team to test (I don't have the
failing hardware).
Only the 100ms version worked every time.

I did request a hardware investigation to clarify the 100ms delays. They
reported the time was needed for the power to stabilize.

> 
> Some customers who care about boot times will not be happy about such
> an aditional delay.  You add this code do board_early_init_f() which
> always gets executed. But actually this is only needed when we want to
> use the USB port in U-Boot, right?  So this should be added to the USB
> init code, and not to the common code.

Actually we need the reset prior to Linux boot as well. Otherwise Linux
will not discover attached devices. Which is the whole reason for the
patch...


Best regards,
-DM
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