From: Guenter Roeck <linux@roeck-us.net>
To: Alan Stern <stern@rowland.harvard.edu>
Cc: Peter Chen <peter.chen@freescale.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
Michael Grzeschik <m.grzeschik@pengutronix.de>,
stable@vger.kernel.org
Subject: Re: [PATCH] usb: chipidea: host: Disable port power only if previously enabled
Date: Fri, 27 Dec 2019 08:55:43 -0800 [thread overview]
Message-ID: <20191227165543.GA15950@roeck-us.net> (raw)
In-Reply-To: <Pine.LNX.4.44L0.1912261428310.6148-100000@netrider.rowland.org>
On Thu, Dec 26, 2019 at 02:46:15PM -0500, Alan Stern wrote:
> On Thu, 26 Dec 2019, Guenter Roeck wrote:
>
> > On shutdown, ehci_power_off() is called unconditionally to power off
> > each port, even if it was never called to power on the port.
> > For chipidea, this results in a call to ehci_ci_portpower() with a request
> > to power off ports even if the port was never powered on.
> > This results in the following warning from the regulator code.
>
> That's weird -- we should always power-on every port during hub
> initialization.
>
That is what I would have assumed, but test code shows that it doesn't
happen.
> It looks like there's a bug in hub.c:hub_activate(): The line under
> HUB_INIT which calls hub_power_on() should call
> usb_hub_set_port_power() instead. In fact, the comment near the start
usb_hub_set_port_power() operates on a port of the hub. hub_activate()
operates on the hub itself, or at least I think it does. I don't know
how to convert the calls. Also, there are more calls to hub_power_on()
in the same function. Can you provide more details on what to do,
or even better a patch for me to test ?
Thanks,
Guenter
> of hub_power_on() is wrong. It says "Enable power on each port", but
> in fact it only enables power for ports that had been powered-on
> previously (i.e., the port's bit in hub->power_bits was set).
> Apparently this got messed up in commit ad493e5e5805 ("usb: add usb
> port auto power off mechanism").
>
> Now, the chipidea driver may still need to be updated, because
> ehci_turn_off_all_ports() will still be called during shutdown and it
> will try to power-down all ports, even those which are already powered
> down (for example, because the port is suspended).
>
> Alan Stern
>
next prev parent reply other threads:[~2019-12-27 16:55 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-26 15:57 [PATCH] usb: chipidea: host: Disable port power only if previously enabled Guenter Roeck
2019-12-26 19:46 ` Alan Stern
2019-12-27 1:45 ` Peter Chen
2019-12-27 14:47 ` Alan Stern
2019-12-27 16:55 ` Guenter Roeck [this message]
2019-12-28 19:33 ` Alan Stern
2019-12-29 16:28 ` Guenter Roeck
2019-12-29 16:40 ` Alan Stern
2019-12-30 0:57 ` Guenter Roeck
2020-01-01 22:09 ` Guenter Roeck
2020-01-02 2:30 ` Alan Stern
2019-12-27 1:45 ` Peter Chen
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