From: Matthias Kaehlcke <mka@chromium.org>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Rob Herring <robh+dt@kernel.org>,
Frank Rowand <frowand.list@gmail.com>,
devicetree@vger.kernel.org, Peter Chen <peter.chen@nxp.com>,
Stephen Boyd <swboyd@chromium.org>,
Alan Stern <stern@rowland.harvard.edu>,
Ravi Chandra Sadineni <ravisadineni@chromium.org>,
Bastien Nocera <hadess@hadess.net>,
linux-kernel@vger.kernel.org,
Douglas Anderson <dianders@chromium.org>,
linux-usb@vger.kernel.org, Krzysztof Kozlowski <krzk@kernel.org>,
Mathias Nyman <mathias.nyman@intel.com>
Subject: Re: [PATCH v5 3/4] usb: host: xhci-plat: Create platform device for onboard hubs in probe()
Date: Thu, 11 Feb 2021 11:01:03 -0800 [thread overview]
Message-ID: <YCV+7z8Y/l0eyse9@google.com> (raw)
In-Reply-To: <YCV7XGloQIjtFAqf@google.com>
On Thu, Feb 11, 2021 at 10:45:48AM -0800, Matthias Kaehlcke wrote:
> Hi Greg,
>
> On Thu, Feb 11, 2021 at 07:58:23AM +0100, Greg Kroah-Hartman wrote:
> > On Wed, Feb 10, 2021 at 09:10:38AM -0800, Matthias Kaehlcke wrote:
> > > Check during probe() if a hub supported by the onboard_usb_hub
> > > driver is connected to the controller. If such a hub is found
> > > create the corresponding platform device. This requires the
> > > device tree to have a node for the hub with its vendor and
> > > product id (which is not common for USB devices). Further the
> > > platform device is only created when CONFIG_USB_ONBOARD_HUB=y/m.
> > >
> > > Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
> > > ---
> > >
> > > Changes in v5:
> > > - patch added to the series
> > >
> > > drivers/usb/host/xhci-plat.c | 16 ++++++++++++++++
> > > include/linux/usb/hcd.h | 2 ++
> > > 2 files changed, 18 insertions(+)
> > >
> > > diff --git a/drivers/usb/host/xhci-plat.c b/drivers/usb/host/xhci-plat.c
> > > index 4d34f6005381..e785fa109eea 100644
> > > --- a/drivers/usb/host/xhci-plat.c
> > > +++ b/drivers/usb/host/xhci-plat.c
> > > @@ -15,6 +15,7 @@
> > > #include <linux/of.h>
> > > #include <linux/of_device.h>
> > > #include <linux/platform_device.h>
> > > +#include <linux/usb/onboard_hub.h>
> > > #include <linux/usb/phy.h>
> > > #include <linux/slab.h>
> > > #include <linux/acpi.h>
> > > @@ -184,6 +185,7 @@ static int xhci_plat_probe(struct platform_device *pdev)
> > > int ret;
> > > int irq;
> > > struct xhci_plat_priv *priv = NULL;
> > > + struct device_node *np;
> > >
> > >
> > > if (usb_disabled())
> > > @@ -356,6 +358,17 @@ static int xhci_plat_probe(struct platform_device *pdev)
> > > */
> > > pm_runtime_forbid(&pdev->dev);
> > >
> > > + np = usb_of_get_device_node(hcd->self.root_hub, hcd->self.busnum);
> > > + if (np && of_is_onboard_usb_hub(np)) {
> > > + struct platform_device *pdev;
> > > +
> > > + pdev = of_platform_device_create(np, NULL, NULL);
> >
> > A platform device is a child of another platform device? Ok, but
> > really, why? What uses this device?
>
> In earlier versions there was a standalone platform device:
> https://lore.kernel.org/patchwork/patch/1313001/
>
> However this was rejected by Rob, since the DT would require a node for the
> platform device and (implicit or explicit) nodes for the USB devices,
> representing the same physical device:
>
> https://lore.kernel.org/patchwork/patch/1305395/
> https://lore.kernel.org/patchwork/patch/1313000/
>
> Both Doug Anderson and myself argued that it seems legitimate to distinguish
> between the devices connected to the USB bus, and the chip which might have
> GPIOs, regulators, clocks, ... but apparently our arguments were not
> convincing enough.
To let the xhci-plat driver create the platform device was suggested by Alan:
https://lore.kernel.org/patchwork/patch/1313000/#1510227
Personally I would favor a standalone platform device, since it provides more
flexiblity (also works for hubs connected to a non-root hub) and doesn't require
cooperation from other driver, however I doubt I could convince Rob of the
corresponding DT bindings.
next prev parent reply other threads:[~2021-02-11 19:12 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-10 17:10 [PATCH v5 0/4] USB: misc: Add onboard_usb_hub driver Matthias Kaehlcke
2021-02-10 17:10 ` [PATCH v5 1/4] dt-bindings: usb: Add binding for discrete onboard USB hubs Matthias Kaehlcke
2021-02-11 14:56 ` Rob Herring
2021-02-17 21:04 ` Rob Herring
2021-02-18 1:33 ` Matthias Kaehlcke
2021-02-19 15:05 ` Rob Herring
2021-02-22 17:39 ` Matthias Kaehlcke
2021-02-10 17:10 ` [PATCH v5 2/4] USB: misc: Add onboard_usb_hub driver Matthias Kaehlcke
2021-02-11 7:03 ` Greg Kroah-Hartman
2021-02-11 18:04 ` Matthias Kaehlcke
2021-02-10 17:10 ` [PATCH v5 3/4] usb: host: xhci-plat: Create platform device for onboard hubs in probe() Matthias Kaehlcke
2021-02-10 21:06 ` Krzysztof Kozlowski
2021-02-10 22:20 ` Matthias Kaehlcke
2021-02-11 19:14 ` Stephen Boyd
2021-02-11 20:36 ` Matthias Kaehlcke
2021-02-11 20:45 ` Stephen Boyd
2021-02-11 22:46 ` Rob Herring
2021-02-11 22:40 ` Rob Herring
2021-02-11 6:58 ` Greg Kroah-Hartman
2021-02-11 18:45 ` Matthias Kaehlcke
2021-02-11 19:01 ` Matthias Kaehlcke [this message]
2021-02-10 17:10 ` [PATCH v5 4/4] arm64: dts: qcom: sc7180-trogdor: Add nodes for onboard USB hub Matthias Kaehlcke
2021-02-10 21:04 ` [PATCH v5 0/4] USB: misc: Add onboard_usb_hub driver Krzysztof Kozlowski
2021-02-10 22:37 ` Matthias Kaehlcke
2021-02-24 13:25 ` Michal Simek
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