From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Lu Baolu <baolu.lu@linux.intel.com>
Cc: felipe.balbi@linux.intel.com,
Mathias Nyman <mathias.nyman@intel.com>,
Lee Jones <lee.jones@linaro.org>,
Heikki Krogerus <heikki.krogerus@linux.intel.com>,
Liam Girdwood <lgirdwood@gmail.com>,
Mark Brown <broonie@kernel.org>,
linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v10 6/7] usb: pci-quirks: add Intel USB drcfg mux device
Date: Wed, 8 Jun 2016 08:45:27 -0700 [thread overview]
Message-ID: <20160608154527.GA16905@kroah.com> (raw)
In-Reply-To: <5757CF94.40803@linux.intel.com>
On Wed, Jun 08, 2016 at 03:56:04PM +0800, Lu Baolu wrote:
> Hi Greg,
>
> On 06/08/2016 12:45 PM, Greg Kroah-Hartman wrote:
> > On Thu, Jun 02, 2016 at 09:37:28AM +0800, Lu Baolu wrote:
> >> In some Intel platforms, a single usb port is shared between USB host
> >> and device controllers. The shared port is under control of a switch
> >> which is defined in the Intel vendor defined extended capability for
> >> xHCI.
> >>
> >> This patch adds the support to detect and create the platform device
> >> for the port mux switch.
> > Why do you need a platform device for this? You do nothing with this
> > device, why create it at all?
>
> In this patch series, I have a generic framework for port mux devices
> and two port mux drivers sitting on top the generic code.
>
> In this patch, I create a platform device for the real mux device in
> Intel Cherry Trail or Broxton SOCs. In it's driver, I registered a mux
> into the generic framework and handle the power management
> things in driver's pm entries (otherwise, the system can't be waken
> up from system suspend).
>
> > And why is it a platform device, isn't is really a PCI device? Why
> > would you ever find a "platform" device below a PCI device? Don't abuse
> > platform devices for things that aren't. It makes me want to delete
> > that whole interface more and more...
>
> Port mux devices are physical devices in Intel Cherry Trail and Broxton
> SOCs. It doesn't sit on any PCIe bus. But it maps its registers in xHCI
> space. OS kernel can enumerate it by looking up the xhci extended
> capability list with a vendor specific capability ID.
A physical device that maps registers into PCI space seems like a PCI
device of some type to me :)
Again, I hate platform devices for obvious reasons like this...
greg k-h
next prev parent reply other threads:[~2016-06-08 15:45 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-02 1:37 [PATCH v10 0/7] usb: add support for Intel dual role port mux Lu Baolu
2016-06-02 1:37 ` [PATCH v10 1/7] regulator: fixed: add support for ACPI interface Lu Baolu
2016-06-08 4:42 ` Greg Kroah-Hartman
2016-06-08 13:43 ` Mark Brown
2016-06-08 15:46 ` Greg Kroah-Hartman
2016-06-09 2:43 ` Lu Baolu
2016-06-02 1:37 ` [PATCH v10 2/7] usb: mux: add generic code for dual role port mux Lu Baolu
2016-06-03 7:41 ` Peter Chen
2016-06-03 8:16 ` Heikki Krogerus
2016-06-03 9:20 ` Peter Chen
2016-06-03 16:06 ` Lu Baolu
2016-06-04 2:28 ` Peter Chen
2016-06-05 6:55 ` Lu Baolu
2016-06-05 8:33 ` Jun Li
2016-06-05 8:46 ` Lu Baolu
2016-06-06 1:08 ` Jun Li
2016-06-06 2:30 ` Lu Baolu
2016-06-06 2:05 ` Peter Chen
2016-06-06 2:45 ` Lu Baolu
2016-06-06 6:48 ` Peter Chen
2016-06-06 1:25 ` Peter Chen
2016-06-06 3:04 ` Lu Baolu
2016-06-06 7:02 ` Roger Quadros
2016-06-07 3:03 ` Jun Li
2016-06-07 6:27 ` Lu Baolu
2016-06-07 6:34 ` Jun Li
2016-06-07 9:27 ` Lu Baolu
2016-06-07 12:49 ` Roger Quadros
2016-06-07 9:53 ` Lu Baolu
2016-06-07 12:58 ` Roger Quadros
2016-06-07 13:04 ` Felipe Balbi
2016-06-07 14:02 ` Roger Quadros
2016-06-07 15:05 ` Felipe Balbi
2016-06-08 3:04 ` Jun Li
[not found] ` <5757A8CB.90402@linux.intel.com>
2016-06-08 6:20 ` Jun Li
2016-06-08 6:25 ` Peter Chen
2016-06-08 7:58 ` Roger Quadros
2016-06-06 7:02 ` Peter Chen
2016-06-06 7:35 ` Lu Baolu
2016-06-02 1:37 ` [PATCH v10 3/7] usb: mux: add driver for Intel gpio controlled " Lu Baolu
2016-06-02 1:37 ` [PATCH v10 4/7] usb: mux: add driver for Intel drcfg " Lu Baolu
2016-06-02 1:37 ` [PATCH v10 5/7] mfd: intel_vuport: Add Intel virtual USB port MFD Driver Lu Baolu
2016-06-02 1:37 ` [PATCH v10 6/7] usb: pci-quirks: add Intel USB drcfg mux device Lu Baolu
2016-06-08 4:45 ` Greg Kroah-Hartman
2016-06-08 7:56 ` Lu Baolu
2016-06-08 15:45 ` Greg Kroah-Hartman [this message]
2016-06-09 2:39 ` Lu Baolu
2016-06-16 0:27 ` Lu Baolu
2016-06-18 0:58 ` Greg Kroah-Hartman
2016-06-19 9:52 ` Lu Baolu
2016-06-02 1:37 ` [PATCH v10 7/7] MAINTAINERS: add maintainer entry for Intel USB dual role mux drivers Lu Baolu
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