| Message ID | 20210210091015.v5.3.I7a3a7d9d2126c34079b1cab87aa0b2ec3030f9b7@changeid |
|---|---|
| State | Superseded |
| Headers | show |
| Series | USB: misc: Add onboard_usb_hub driver | expand |
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? thanks, greg k-h
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.
Quoting Matthias Kaehlcke (2021-02-10 14:20:18) > > On Wed, Feb 10, 2021 at 10:06:45PM +0100, Krzysztof Kozlowski wrote: > > > > This looks hackish... what if later we have something else than hub? > > Another if()? > > > > What if hub could be connected to something else than XHCI controller? > > In earlier versions this was standalone driver, which was more flexible and > didn't require cooperation from the XHCI driver: > > https://lore.kernel.org/patchwork/patch/1313001/ > > Rob Herring raised objections about the DT bindings, since the USB hub would be > represented twice in the DT, once in the USB hierachry (with an explicit node or > implicitly) plus a node for the platform device for the new driver: > > https://lore.kernel.org/patchwork/patch/1305395/ > https://lore.kernel.org/patchwork/patch/1313000/ > > Alan Stern suggested to create the platform device in the XHCI platform driver: > > https://lore.kernel.org/patchwork/patch/1313000/#1510227 > > I wasn't super happy about involving xhci-plat, but at least the code is minimal > and all the device specific stuff is handled by the onboard_usb_hub driver. > > If you have better suggestions that might satisfy all parties please let us > know :) > Is it possible to use the graph binding to connect the USB controller on the SoC to the port on the hub? Then the hub would be a standalone node at the root of DT connected to the USB controller (or phy) and xhci code could probe the firmware to see if there's a graph connection downstream that is a powered hub like this. I didn't see this idea mentioned in the previous discussions, but maybe I missed it.
Quoting Matthias Kaehlcke (2021-02-11 12:36:35) > Hi Stephen, > > On Thu, Feb 11, 2021 at 11:14:39AM -0800, Stephen Boyd wrote: > > > > Is it possible to use the graph binding to connect the USB controller on > > the SoC to the port on the hub? Then the hub would be a standalone node > > at the root of DT connected to the USB controller (or phy) and xhci code > > could probe the firmware to see if there's a graph connection downstream > > that is a powered hub like this. I didn't see this idea mentioned in the > > previous discussions, but maybe I missed it. > > Thanks for bringing this up. I'm not sure I completely understand your > suggestion, but in general it seems a direction that could be worth > exploring. Cool. > > I think something like the following should work even without requiring > cooperation from the XHCI code: > > onboard-usb-hub { > compatible = “realtek,rts5411”, “onboard_usb_hub”; > #address-cells = <1>; > #size-cells = <0>; > > vdd-supply = <&pp3300_hub>; > > port@0 { > reg = <0>; > > rts5411_3_0: endpoint { > // should not be needed > remote-endpoint = <&usb_1_dwc3_port1>; > }; > }; > > port@1 { > reg = <1>; > > rts5411_2_0: endpoint { > // should not be needed > remote-endpoint = <&usb_1_dwc3_port2>; > }; > }; > }; > > &usb_1_dwc3 { > dr_mode = "host"; > #address-cells = <1>; > #size-cells = <0>; > > port@1 { > reg = <1>; > > usb_1_dwc3_port1: endpoint { > remote-endpoint = <&rts5411_3_0>; > }; > }; > > port@2 { > reg = <2>; > > usb_1_dwc3_port2: endpoint { > remote-endpoint = <&rts5411_2_0>; > }; > }; > }; > > That looks like an actual description of the hardware, without multiple DT > nodes for the hub. > > The USB part of the onboard_hub driver could determine the platform device > from the remote endpoint and register the USB device with it. Yeah you got it, this is what I'm suggesting. I'd like to go even further and also describe the ports on "the other side" or "downstream facing side" of the USB hub that go to things like type-c ports or type-a ports. This would allow us to describe the USB topology and how it is physically connected to ports on the device that humans see. But that's mostly a job for the type-c subsystem, so it's a parallel discussion that's only related because of the graph binding.
On Thu, Feb 11, 2021 at 2:45 PM Stephen Boyd <swboyd@chromium.org> wrote: > > Quoting Matthias Kaehlcke (2021-02-11 12:36:35) > > Hi Stephen, > > > > On Thu, Feb 11, 2021 at 11:14:39AM -0800, Stephen Boyd wrote: > > > > > > Is it possible to use the graph binding to connect the USB controller on > > > the SoC to the port on the hub? Then the hub would be a standalone node > > > at the root of DT connected to the USB controller (or phy) and xhci code > > > could probe the firmware to see if there's a graph connection downstream > > > that is a powered hub like this. I didn't see this idea mentioned in the > > > previous discussions, but maybe I missed it. > > > > Thanks for bringing this up. I'm not sure I completely understand your > > suggestion, but in general it seems a direction that could be worth > > exploring. > > Cool. > > > > > I think something like the following should work even without requiring > > cooperation from the XHCI code: > > > > onboard-usb-hub { > > compatible = “realtek,rts5411”, “onboard_usb_hub”; > > #address-cells = <1>; > > #size-cells = <0>; > > > > vdd-supply = <&pp3300_hub>; > > > > port@0 { > > reg = <0>; > > > > rts5411_3_0: endpoint { > > // should not be needed > > remote-endpoint = <&usb_1_dwc3_port1>; > > }; > > }; > > > > port@1 { > > reg = <1>; > > > > rts5411_2_0: endpoint { > > // should not be needed > > remote-endpoint = <&usb_1_dwc3_port2>; > > }; > > }; > > }; > > > > &usb_1_dwc3 { > > dr_mode = "host"; > > #address-cells = <1>; > > #size-cells = <0>; > > > > port@1 { > > reg = <1>; > > > > usb_1_dwc3_port1: endpoint { > > remote-endpoint = <&rts5411_3_0>; > > }; > > }; > > > > port@2 { > > reg = <2>; > > > > usb_1_dwc3_port2: endpoint { > > remote-endpoint = <&rts5411_2_0>; > > }; > > }; > > }; > > > > That looks like an actual description of the hardware, without multiple DT > > nodes for the hub. > > > > The USB part of the onboard_hub driver could determine the platform device > > from the remote endpoint and register the USB device with it. > > Yeah you got it, this is what I'm suggesting. I'd like to go even > further and also describe the ports on "the other side" or "downstream > facing side" of the USB hub that go to things like type-c ports or > type-a ports. This would allow us to describe the USB topology and how > it is physically connected to ports on the device that humans see. But > that's mostly a job for the type-c subsystem, so it's a parallel > discussion that's only related because of the graph binding. I'd like to see a complete case that includes connectors. I really need someone to worry about USB bindings with a view on the big picture. The piecemeal additions don't result in the best design. Rob
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); + if (pdev) + hcd->onboard_hub_dev = &pdev->dev; + else + xhci_warn(xhci, "failed to create onboard hub platform device\n"); + } + return 0; @@ -402,6 +415,9 @@ static int xhci_plat_remove(struct platform_device *dev) usb_remove_hcd(hcd); usb_put_hcd(shared_hcd); + if (hcd->onboard_hub_dev) + of_platform_device_destroy(hcd->onboard_hub_dev, NULL); + clk_disable_unprepare(clk); clk_disable_unprepare(reg_clk); usb_put_hcd(hcd); diff --git a/include/linux/usb/hcd.h b/include/linux/usb/hcd.h index 96281cd50ff6..d02a508e19b0 100644 --- a/include/linux/usb/hcd.h +++ b/include/linux/usb/hcd.h @@ -225,6 +225,8 @@ struct usb_hcd { * (ohci 32, uhci 1024, ehci 256/512/1024). */ + struct device *onboard_hub_dev; + /* The HC driver's private data is stored at the end of * this structure. */
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(+)