Re: [PATCH v2 3/4] usb: chipidea: tegra: Avoid controller/PHY init if bus is externally controlled

["Peter Chen (CIX)" <peter.chen@kernel.org>]

On 26-05-25 17:43:42, Svyatoslav Ryhel wrote:
> сб, 23 трав. 2026 р. о 11:30 Svyatoslav Ryhel <clamor95@gmail.com> пише:
> >
> > If the USB controller and PHY are externally controlled, then the
> > registration of the controller and the PHY initialization should be
> > skipped, since these configurations must be done by the device that
> > controls the bus to work correctly.
> >
> > Since USB PHY in Tegra controls clock gates required by the controller
> > itself, Chipidea core PHY management is not suitable for Tegra.
> >
> > Signed-off-by: Svyatoslav Ryhel <clamor95@gmail.com>
> > ---
> >  drivers/usb/chipidea/ci_hdrc_tegra.c | 32 ++++++++++++++++++----------
> >  1 file changed, 21 insertions(+), 11 deletions(-)
> >
> 
> Hello there!
> 
> This patch is required because I could not find an acceptable way to
> manually remove and add a platform device. I will explain the details
> below and hope that someone can give me some suggestions on how to
> handle this situation.
> 
> The Tegra USB controller is the root node, and it is bound and probed
> automatically. This is perfectly fine for ordinary use cases. On the
> other hand, the modem used in Tegra 3 devices requires the USB
> controller to be registered at the exact moment when the modem is
> ready to handle USB. If this window is not respected, the modem will
> not expose the USB device, and all you get is a cascade of enumeration
> failures.

Could you add USB controller device node as the child node for modem,
and dynamic creating USB controller device during modem probe?

Peter

> 
> The solution as I see it right now: The modem has a power sequencing
> driver, and the USB controller can either be autoprobed and
> unregistered in the pseq probe and then registered/unregistered in the
> on/off sequences, or it can have a status = "reserved" set in the USB
> node and manually register/unregister it during the pseq on/off
> sequences. This would eliminate the need for this patch.
> 
> The problem I have faced is that I cannot properly and manually
> control the USB controller driver to bind -> probe it and remove ->
> unbind it from within powerseq.
> 
> Help is appreciated. Thanks!
> 
> Best regards,
> Svyatoslav R.

-- 

Best regards,
Peter