linux-kernel - Re: [PATCH v6 0/5] Fix USB suspend on TI J7200 (cdns3-ti, cdns3, xhci)

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Message-Id: <D6D6NEMYVOBV.3OVBJ77E11A2@bootlin.com>
Date: Mon, 16 Dec 2024 15:09:00 +0100
From: Théo Lebrun <theo.lebrun@...tlin.com>
To: "Peter Chen" <peter.chen@...nel.org>
Cc: "Pawel Laszczak" <pawell@...ence.com>, "Roger Quadros"
 <rogerq@...nel.org>, "Greg Kroah-Hartman" <gregkh@...uxfoundation.org>,
 "Mathias Nyman" <mathias.nyman@...el.com>, Grégory Clement
 <gregory.clement@...tlin.com>, "Thomas Petazzoni"
 <thomas.petazzoni@...tlin.com>, <linux-usb@...r.kernel.org>,
 <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v6 0/5] Fix USB suspend on TI J7200 (cdns3-ti, cdns3,
 xhci)

Hello Peter,

On Sat Dec 14, 2024 at 10:06 AM CET, Peter Chen wrote:
> On 24-12-10 18:13:34, Théo Lebrun wrote:
> > Currently, system-wide suspend is broken on J7200 because of a
> > controller reset. The TI wrapper does not get re-initialised at resume
> > and the first register access from cdns core fails.
> > 
> > We address that in two ways:
> > 
> >  - In the cdns3-ti wrapper, if a reset has occured at resume,
> >    we reconfigure the hardware.
> > 
> >  - We add a xhci->lost_power flag. Identical to the XHCI_RESET_ON_RESUME
> >    quirk, expect that it can be set at runtime.
> > 
> >    At resume, to summarise, we do:
> >       xhci->lost_power = cdns_power_is_lost(cdns);
>
> Is it possible you go to change xhci quirks runtime?

I always assumed quirks were read-only once probe was finished.
If I was wrong then we can remove xhci->lost_power and edit
xhci->quirks instead.

Thanks,

--
Théo Lebrun, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com