From: Hans de Goede <hdegoede@redhat.com>
To: John Stultz <john.stultz@linaro.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: lkml <linux-kernel@vger.kernel.org>,
Yu Chen <chenyu56@huawei.com>, Rob Herring <robh+dt@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Heikki Krogerus <heikki.krogerus@linux.intel.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Chunfeng Yun <chunfeng.yun@mediatek.com>,
Felipe Balbi <balbi@kernel.org>,
Andy Shevchenko <andy.shevchenko@gmail.com>,
Jun Li <lijun.kernel@gmail.com>,
Valentin Schneider <valentin.schneider@arm.com>,
Linux USB List <linux-usb@vger.kernel.org>,
"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
<devicetree@vger.kernel.org>
Subject: Re: [RFC][PATCH 2/3] usb: roles: Add usb role switch notifier.
Date: Thu, 3 Oct 2019 22:56:24 +0200 [thread overview]
Message-ID: <9cfccb6a-fba1-61a3-3eb6-3009c2f5e747@redhat.com> (raw)
In-Reply-To: <CALAqxLWm_u3KsXHn4a6PdBCOKM1vs5k0xS3G5jY+M-=HBqUJag@mail.gmail.com>
Hi,
On 03-10-2019 22:45, John Stultz wrote:
> On Thu, Oct 3, 2019 at 4:26 AM Greg Kroah-Hartman
> <gregkh@linuxfoundation.org> wrote:
>>
>> On Wed, Oct 02, 2019 at 11:16:16PM +0000, John Stultz wrote:
>>> From: Yu Chen <chenyu56@huawei.com>
>>>
>>> This patch adds notifier for drivers want to be informed of the usb role
>>> switch.
>>
>> Ick, I hate notifiers, they always come back to cause problems.
>>
>> What's just wrong with a "real" call to who ever needs to know this?
>> And who does need to know this anyway? Like Hans said, if we don't have
>> a user for it, we should not add it.
>
> So in this case, its used for interactions between the dwc3 driver and
> the hikey960 integrated USB hub, which is controlled via gpio (which I
> didn't submit here as I was trying to keep things short and
> reviewable, but likely misjudged).
>
> The HiKey960 has only one USB controller, but in order to support both
> USB-C gadget/OTG and USB-A (host only) ports. When the USB-C
> connection is attached, it powers down and disconnects the hub. When
> the USB-C connection is detached, it powers the hub on and connects
> the controller to the hub.
When you say one controller, do you mean 1 host and 1 gadget controller,
or is this one of these lovely devices where a gadget controller gets
abused as / confused with a proper host controller?
And since you are doing a usb-role-switch driver, I guess that the
role-switch is integrated inside the SoC, so you only get one pair
of USB datalines to the outside ?
This does seem rather special, it might help if you can provide a diagram
with both the relevant bits inside the SoC as well as what lives outside
the Soc. even if it is in ASCII art...
Regards,
Hans
next prev parent reply other threads:[~2019-10-03 20:56 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-02 23:16 [RFC][PATCH 0/3] dwc3 role-switch handling for HiKey960 John Stultz
2019-10-02 23:16 ` [RFC][PATCH 1/3] dt-bindings: usb: generic: Add role-switch-default-host binding John Stultz
2019-10-02 23:16 ` [RFC][PATCH 2/3] usb: roles: Add usb role switch notifier John Stultz
2019-10-03 9:25 ` Hans de Goede
2019-10-03 20:37 ` John Stultz
2019-10-03 20:37 ` John Stultz
2019-10-03 20:51 ` Hans de Goede
2019-10-03 20:51 ` Hans de Goede
2019-10-04 8:12 ` Heikki Krogerus
2019-10-04 8:12 ` Heikki Krogerus
2019-10-15 5:39 ` John Stultz
2019-10-15 5:39 ` John Stultz
2019-10-16 7:27 ` Hans de Goede
2019-10-18 5:55 ` John Stultz
2019-10-18 8:06 ` Hans de Goede
2019-10-18 18:39 ` John Stultz
2019-10-18 19:30 ` Hans de Goede
2019-10-18 19:53 ` John Stultz
2019-10-18 19:59 ` Hans de Goede
2019-10-18 20:12 ` John Stultz
2019-10-18 20:21 ` Hans de Goede
2019-10-18 20:37 ` John Stultz
2019-10-18 21:05 ` Hans de Goede
2019-10-22 5:58 ` John Stultz
2019-11-14 10:11 ` Hans de Goede
2019-11-15 0:23 ` John Stultz
2019-10-16 9:10 ` Hans de Goede
2019-10-03 11:26 ` Greg Kroah-Hartman
2019-10-03 20:45 ` John Stultz
2019-10-03 20:45 ` John Stultz
2019-10-03 20:56 ` Hans de Goede [this message]
2019-10-03 20:56 ` Hans de Goede
2019-10-03 21:33 ` John Stultz
2019-10-03 21:33 ` John Stultz
2019-10-06 15:22 ` Hans de Goede
2019-10-06 15:22 ` Hans de Goede
2019-10-15 7:03 ` John Stultz
2019-10-15 7:03 ` John Stultz
2019-10-04 8:00 ` Heikki Krogerus
2019-10-04 8:00 ` Heikki Krogerus
2019-10-02 23:16 ` [RFC][PATCH 3/3] usb: dwc3: Registering a role switch in the DRD code John Stultz
2019-10-03 0:32 ` kbuild test robot
2019-10-03 0:43 ` John Stultz
2019-10-13 22:01 ` kbuild test robot
2019-10-15 8:25 ` Roger Quadros
2019-10-15 8:25 ` Roger Quadros
2019-10-15 19:10 ` John Stultz
2019-10-16 9:24 ` Roger Quadros
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