Re: [PATCH usb-next v10 3/8] usb: core: add a wrapper for the USB PHYs on the HCD

Chunfeng Yun
2018-03-22T08:10:45Z

Hi,
On Wed, 2018-03-21 at 13:30 +0200, Roger Quadros wrote:
> Martin,
>
> On 21/03/18 00:01, Martin Blumenstingl wrote:
> > Hi Roger, Hi Chunfeng,
> >
> > On Tue, Mar 20, 2018 at 1:04 PM, Chunfeng Yun <chunfeng.yun-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org> wrote:
> >> Hi Martin & Roger:
> >>
> >> On Mon, 2018-03-19 at 17:12 +0100, Martin Blumenstingl wrote:
> >>> Hi Roger,
> >>>
> >>> On Mon, Mar 19, 2018 at 9:49 AM, Roger Quadros <rogerq-l0cyMroinI0@public.gmane.org> wrote:
> >>>> Hi,
> >>>>
> >>>> On 19/03/18 00:29, Martin Blumenstingl wrote:
> >>>>> Hi Roger,
> >>>>>
> >>>>> On Fri, Mar 16, 2018 at 3:32 PM, Roger Quadros <rogerq-l0cyMroinI0@public.gmane.org> wrote:
> >>>>>> +some TI folks
> >>>>>>
> >>>>>> Hi Martin,
> >>>>>>
> >>>>>> On 18/02/18 20:44, Martin Blumenstingl wrote:
> >>>>>>> Many SoC platforms have separate devices for the USB PHY which are
> >>>>>>> registered through the generic PHY framework. These PHYs have to be
> >>>>>>> enabled to make the USB controller actually work. They also have to be
> >>>>>>> disabled again on shutdown/suspend.
> >>>>>>>
> >>>>>>> Currently (at least) the following HCI platform drivers are using custom
> >>>>>>> code to obtain all PHYs via devicetree for the roothub/controller and
> >>>>>>> disable/enable them when required:
> >>>>>>> - ehci-platform.c has ehci_platform_power_{on,off}
> >>>>>>> - xhci-mtk.c has xhci_mtk_phy_{init,exit,power_on,power_off}
> >>>>>>> - ohci-platform.c has ohci_platform_power_{on,off}
> >>>>>>>
> >>>>>>> With this new wrapper the USB PHYs can be specified directly in the
> >>>>>>> USB controller's devicetree node (just like on the drivers listed
> >>>>>>> above). This allows SoCs like the Amlogic Meson GXL family to operate
> >>>>>>> correctly once this is wired up correctly. These SoCs use a dwc3
> >>>>>>> controller and require all USB PHYs to be initialized (if one of the USB
> >>>>>>> PHYs it not initialized then none of USB port works at all).
> >>>>>>>
> >>>>>>> Signed-off-by: Martin Blumenstingl <martin.blumenstingl-gM/Ye1E23mwN+BqQ9rBEUg@public.gmane.org>
> >>>>>>> Tested-by: Yixun Lan <yixun.lan-LpR1jeaWuhtBDgjK7y7TUQ@public.gmane.org>
> >>>>>>> Cc: Neil Armstrong <narmstrong-rdvid1DuHRBWk0Htik3J/w@public.gmane.org>
> >>>>>>> Cc: Chunfeng Yun <chunfeng.yun-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org>
> >>>>>>
> >>>>>> This patch is breaking low power cases on TI SoCs when USB is in host mode.
> >>>>>> I'll explain why below.
> >>>>> based on your explanation and reading the TI PHY drivers I am assuming
> >>>>> that the affected SoCs are using the "phy-omap-usb2" driver
> >>>>>
> >>>> yes and phy-ti-pipe3 as well i.e. "ti,phy-usb3" and "ti,omap-usb3"
> >>> I missed that, thanks
> >>>
> >>>>>>> ---
> >>>>>>> drivers/usb/core/Makefile | 2 +-
> >>>>>>> drivers/usb/core/phy.c | 158 ++++++++++++++++++++++++++++++++++++++++++++++
> >>>>>>> drivers/usb/core/phy.h | 7 ++
> >>>>>>> 3 files changed, 166 insertions(+), 1 deletion(-)
> >>>>>>> create mode 100644 drivers/usb/core/phy.c
> >>>>>>> create mode 100644 drivers/usb/core/phy.h
> >>>>>>>
> >>>>>>> diff --git a/drivers/usb/core/Makefile b/drivers/usb/core/Makefile
> >>>>>>> index 92c9cefb4317..18e874b0441e 100644
> >>>>>>> --- a/drivers/usb/core/Makefile
> >>>>>>> +++ b/drivers/usb/core/Makefile
> >>>>>>> @@ -6,7 +6,7 @@
> >>>>>>> usbcore-y := usb.o hub.o hcd.o urb.o message.o driver.o
> >>>>>>> usbcore-y += config.o file.o buffer.o sysfs.o endpoint.o
> >>>>>>> usbcore-y += devio.o notify.o generic.o quirks.o devices.o
> >>>>>>> -usbcore-y += port.o
> >>>>>>> +usbcore-y += phy.o port.o
> >>>>>>>
> >>>>>>> usbcore-$(CONFIG_OF) += of.o
> >>>>>>> usbcore-$(CONFIG_USB_PCI) += hcd-pci.o
> >>>>>>> diff --git a/drivers/usb/core/phy.c b/drivers/usb/core/phy.c
> >>>>>>> new file mode 100644
> >>>>>>> index 000000000000..09b7c43c0ea4
> >>>>>>> --- /dev/null
> >>>>>>> +++ b/drivers/usb/core/phy.c
> >>>>>>> @@ -0,0 +1,158 @@
> >>>>>>> +// SPDX-License-Identifier: GPL-2.0+
> >>>>>>> +/*
> >>>>>>> + * A wrapper for multiple PHYs which passes all phy_* function calls to
> >>>>>>> + * multiple (actual) PHY devices. This is comes handy when initializing
> >>>>>>> + * all PHYs on a HCD and to keep them all in the same state.
> >>>>>>> + *
> >>>>>>> + * Copyright (C) 2018 Martin Blumenstingl <martin.blumenstingl-gM/Ye1E23mwN+BqQ9rBEUg@public.gmane.org>
> >>>>>>> + */
> >>>>>>> +
> >>>>>>> +#include <linux/device.h>
> >>>>>>> +#include <linux/list.h>
> >>>>>>> +#include <linux/phy/phy.h>
> >>>>>>> +#include <linux/of.h>
> >>>>>>> +
> >>>>>>> +#include "phy.h"
> >>>>>>> +
> >>>>>>> +struct usb_phy_roothub {
> >>>>>>> + struct phy *phy;
> >>>>>>> + struct list_head list;
> >>>>>>> +};
> >>>>>>> +
> >>>>>>> +static struct usb_phy_roothub *usb_phy_roothub_alloc(struct device *dev)
> >>>>>>> +{
> >>>>>>> + struct usb_phy_roothub *roothub_entry;
> >>>>>>> +
> >>>>>>> + roothub_entry = devm_kzalloc(dev, sizeof(*roothub_entry), GFP_KERNEL);
> >>>>>>> + if (!roothub_entry)
> >>>>>>> + return ERR_PTR(-ENOMEM);
> >>>>>>> +
> >>>>>>> + INIT_LIST_HEAD(&roothub_entry->list);
> >>>>>>> +
> >>>>>>> + return roothub_entry;
> >>>>>>> +}
> >>>>>>> +
> >>>>>>> +static int usb_phy_roothub_add_phy(struct device *dev, int index,
> >>>>>>> + struct list_head *list)
> >>>>>>> +{
> >>>>>>> + struct usb_phy_roothub *roothub_entry;
> >>>>>>> + struct phy *phy = devm_of_phy_get_by_index(dev, dev->of_node, index);
> >>>>>>> +
> >>>>>>> + if (IS_ERR_OR_NULL(phy)) {
> >>>>>>> + if (!phy || PTR_ERR(phy) == -ENODEV)
> >>>>>>> + return 0;
> >>>>>>> + else
> >>>>>>> + return PTR_ERR(phy);
> >>>>>>> + }
> >>>>>>> +
> >>>>>>> + roothub_entry = usb_phy_roothub_alloc(dev);
> >>>>>>> + if (IS_ERR(roothub_entry))
> >>>>>>> + return PTR_ERR(roothub_entry);
> >>>>>>> +
> >>>>>>> + roothub_entry->phy = phy;
> >>>>>>> +
> >>>>>>> + list_add_tail(&roothub_entry->list, list);
> >>>>>>> +
> >>>>>>> + return 0;
> >>>>>>> +}
> >>>>>>> +
> >>>>>>> +struct usb_phy_roothub *usb_phy_roothub_init(struct device *dev)
> >>>>>>> +{
> >>>>>>> + struct usb_phy_roothub *phy_roothub;
> >>>>>>> + struct usb_phy_roothub *roothub_entry;
> >>>>>>> + struct list_head *head;
> >>>>>>> + int i, num_phys, err;
> >>>>>>> +
> >>>>>>> + num_phys = of_count_phandle_with_args(dev->of_node, "phys",
> >>>>>>> + "#phy-cells");
> >>>>>>> + if (num_phys <= 0)
> >>>>>>> + return NULL;
> >>>>>>> +
> >>>>>>> + phy_roothub = usb_phy_roothub_alloc(dev);
> >>>>>>> + if (IS_ERR(phy_roothub))
> >>>>>>> + return phy_roothub;
> >>>>>>> +
> >>>>>>> + for (i = 0; i < num_phys; i++) {
> >>>>>>> + err = usb_phy_roothub_add_phy(dev, i, &phy_roothub->list);
> >>>>>>> + if (err)
> >>>>>>> + goto err_out;
> >>>>>>> + }
> >>>>>>> +
> >>>>>>> + head = &phy_roothub->list;
> >>>>>>> +
> >>>>>>> + list_for_each_entry(roothub_entry, head, list) {
> >>>>>>> + err = phy_init(roothub_entry->phy);
> >>>>>>
> >>>>>> The phy_init() function actually enables the PHY clocks.
> >>>>>> It should be moved to the usb_phy_roothub_exit() routine just before calling phy_power_on().
> >>>>> do you mean that phy_init should be moved to usb_phy_roothub_power_on
> >>>>> (just before phy_power_on is called within usb_phy_roothub_power_on)?
> >>>>>
> >>>>
> >>>> Yes.
> >>>>
> >>>>> an earlier version of my patch did exactly this, but it caused
> >>>>> problems during a suspend/resume cycle on Mediatek devices
> >>>>> Chunfeng Yun reported that issue here [0], quote from that mail for
> >>>>> easier reading:
> >>>>> "In order to keep link state on mt8173, we just power off all phys(not
> >>>>> exit) when system enter suspend, then power on them again (needn't
> >>>>> init, otherwise device will be disconnected) when system resume, this
> >>>>> can avoid re-enumerating device."
> >>>>>
> >>>>>>> + if (err)
> >>>>>>> + goto err_exit_phys;
> >>>>>>> + }
> >>>>>>> +
> >>>>>>> + return phy_roothub;
> >>>>>>> +
> >>>>>>> +err_exit_phys:
> >>>>>>> + list_for_each_entry_continue_reverse(roothub_entry, head, list)
> >>>>>>> + phy_exit(roothub_entry->phy);
> >>>>>>> +
> >>>>>>> +err_out:
> >>>>>>> + return ERR_PTR(err);
> >>>>>>> +}
> >>>>>>> +EXPORT_SYMBOL_GPL(usb_phy_roothub_init);
> >>>>>>> +
> >>>>>>> +int usb_phy_roothub_exit(struct usb_phy_roothub *phy_roothub)
> >>>>>>> +{
> >>>>>>> + struct usb_phy_roothub *roothub_entry;
> >>>>>>> + struct list_head *head;
> >>>>>>> + int err, ret = 0;
> >>>>>>> +
> >>>>>>> + if (!phy_roothub)
> >>>>>>> + return 0;
> >>>>>>> +
> >>>>>>> + head = &phy_roothub->list;
> >>>>>>> +
> >>>>>>> + list_for_each_entry(roothub_entry, head, list) {
> >>>>>>> + err = phy_exit(roothub_entry->phy);
> >>>>>>> + if (err)
> >>>>>>> + ret = ret;
> >>>>>>> + }
> >>>>>>
> >>>>>> phy_exit() should be moved to usb_phy_roothub_poweroff() just after calling phy_power_off().
> >>>>> if I understood Chunfeng Yun correctly this will require
> >>>>> re-enumeration of the USB devices after a suspend/resume cycle on
> >>>>> Mediatek SoCs
> >>>>>
> >>>>
> >>>> OK. I suppose that there are 2 cases
> >>>> 1) Mediatek's case: USB controller context retained across suspend/resume.
> >>>> Remote wakeup probably required.
> >>>> No re-enumeration preferred after resume. phy_exit()/phy_init() must not be called
> >>>> during suspend/resume to keep PHY link active.
> >>> Documentation/devicetree/bindings/usb/mediatek,mtu3.txt indeed shows
> >>> that the parent of the USB controller can be marked as "wakeup-source"
> >>>
> >>>> 2) TI's case: low power important: USB context is lost, OK to re-enumerate.
> >>>> phy_exit()/phy_init() must be called during suspend/resume.
> >>> ACK
> >>>
> >>>>>> With that there is nothing else being done here. Shouldn't we be doing the equivalent of
> >>>>>> usb_phy_roothub_del_phy() and usb_phy_roothub_free() here?
> >>>>>>
> >>>>>>> +
> >>>>>>> + return ret;
> >>>>>>> +}
> >>>>>>> +EXPORT_SYMBOL_GPL(usb_phy_roothub_exit);
> >>>>>>> +
> >>>>>>> +int usb_phy_roothub_power_on(struct usb_phy_roothub *phy_roothub)
> >>>>>>> +{
> >>>>>>> + struct usb_phy_roothub *roothub_entry;
> >>>>>>> + struct list_head *head;
> >>>>>>> + int err;
> >>>>>>> +
> >>>>>>> + if (!phy_roothub)
> >>>>>>> + return 0;
> >>>>>>> +
> >>>>>>> + head = &phy_roothub->list;
> >>>>>>> +
> >>>>>>> + list_for_each_entry(roothub_entry, head, list) {
> >>>>>>> + err = phy_power_on(roothub_entry->phy);
> >>>>>>> + if (err)
> >>>>>>> + goto err_out;
> >>>>>>> + }
> >>>>>>> +
> >>>>>>> + return 0;
> >>>>>>> +
> >>>>>>> +err_out:
> >>>>>>> + list_for_each_entry_continue_reverse(roothub_entry, head, list)
> >>>>>>> + phy_power_off(roothub_entry->phy);
> >>>>>>> +
> >>>>>>> + return err;
> >>>>>>> +}
> >>>>>>> +EXPORT_SYMBOL_GPL(usb_phy_roothub_power_on);
> >>>>>>> +
> >>>>>>> +void usb_phy_roothub_power_off(struct usb_phy_roothub *phy_roothub)
> >>>>>>> +{
> >>>>>>> + struct usb_phy_roothub *roothub_entry;
> >>>>>>> +
> >>>>>>> + if (!phy_roothub)
> >>>>>>> + return;
> >>>>>>> +
> >>>>>>> + list_for_each_entry_reverse(roothub_entry, &phy_roothub->list, list)
> >>>>>>> + phy_power_off(roothub_entry->phy);
> >>>>>>
> >>>>>> Not doing the phy_exit() here leaves the clocks enabled on our SoC and
> >>>>>> we're no longer able to reach low power states on system suspend.
> >>>>> I'm not sure where this problem should be solved:
> >>>>> - set skip_phy_initialization in struct usb_hcd to 1 for the affected
> >>>>> TI platforms
> >>>>
> >>>> Many TI platforms are affected, omap5*, dra7*, am43*
> >>>>
> >>>>> - fix this in the usb_phy_roothub code
> >>>>
> >>>> I'd vote for fixing it in the usb_phy_roothub code. How?
> >>>> How about using the device_can_wakeup() to decide if we should call phy_exit()/init() or not?
> >>>> If the USB device can't wakeup the system there is no point in keeping it powered/clocked right?
> >>> @Chunfeng: can you confirm Roger's idea that we could call phy_exit if
> >>> the controller is *NOT* marked as "wakeup-source"?
> >>> I am also not sure if it would work, since the "wakeup-source"
> >>> property is defined on the USB controller's parent node in case of the
> >>> Mediatek MTU3 (Mediatek USB3.0 DRD) controller
> >>>
> >> Very sorry, I forgot that MTU3 & xHCI drivers always set them as wakeup
> >> devices by device_init_wakeup(dev, true),but not dependent on
> >> "wakeup-source" property, so maybe we can use device_can_wakeup() to
> >> decide whether call phy_exit()/init() or not.
> > the 64-bit Amlogic Meson GXL/GXM SoCs don't support suspend/resume
> > yet, so I cannot test this
> > based on this suggestion I threw up two patches which are *compile
> > tested only* based on Greg's usb-next branch
> > you can find them here: [0] (as well as attached to this mail)
> >
> > @Chunfeng: can you please test this on one of your Mediatek SoCs?
> > @Roger: can you please test this on a TI SoC?
> >
> > (apologies in advance if these patches don't work)
> >
> > please note that I won't have access to my computer until Saturday.
> > if these patches need to be rewritten/replaced/etc. then feel free to
> > send your own version to the list
>
> Had to do the following to build
>
> diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c
> index 6d4a419..2884607 100644
> --- a/drivers/usb/core/hcd.c
> +++ b/drivers/usb/core/hcd.c
> @@ -2262,7 +2262,7 @@ int hcd_bus_suspend(struct usb_device *rhdev, pm_message_t msg)
> hcd->state = HC_STATE_SUSPENDED;
>
> if (!PMSG_IS_AUTO(msg))
> - usb_phy_roothub_suspend(hcd->phy_roothub);
> + usb_phy_roothub_suspend(&rhdev->dev, hcd->phy_roothub);

Try to use hcd->self.controller instead of &rhdev->dev;

>
> /* Did we race with a root-hub wakeup event? */
> if (rhdev->do_remote_wakeup) {
> @@ -2302,7 +2302,7 @@ int hcd_bus_resume(struct usb_device *rhdev, pm_message_t msg)
> }
>
> if (!PMSG_IS_AUTO(msg)) {
> - status = usb_phy_roothub_resume(hcd->phy_roothub);
> + status = usb_phy_roothub_resume(&rhdev->dev, hcd->phy_roothub);
ditto
> if (status)
> return status;
> }
> @@ -2344,7 +2344,7 @@ int hcd_bus_resume(struct usb_device *rhdev, pm_message_t msg)
> }
> } else {
> hcd->state = old_state;
> - usb_phy_roothub_suspend(hcd->phy_roothub);
> + usb_phy_roothub_suspend(&rhdev->dev, hcd->phy_roothub);
ditto
> dev_dbg(&rhdev->dev, "bus %s fail, err %d\n",
> "resume", status);
> if (status != -ESHUTDOWN)
>
>
> And the following to fix runtime issues
>
> diff --git a/drivers/usb/core/phy.c b/drivers/usb/core/phy.c
> index 2eca371..8598906 100644
> --- a/drivers/usb/core/phy.c
> +++ b/drivers/usb/core/phy.c
> @@ -32,9 +32,9 @@ static int usb_phy_roothub_add_phy(struct device *dev, int index,
> return PTR_ERR(phy);
> }
>
> - roothub_entry = usb_phy_roothub_alloc(dev);
> - if (IS_ERR(roothub_entry))
> - return PTR_ERR(roothub_entry);
> + roothub_entry = devm_kzalloc(dev, sizeof(*roothub_entry), GFP_KERNEL);
> + if (!roothub_entry)
> + return -ENOMEM;
>
> roothub_entry->phy = phy;
>
> @@ -162,7 +162,7 @@ int usb_phy_roothub_suspend(struct device *dev,
> usb_phy_roothub_power_off(phy_roothub);
>
> /* keep the PHYs initialized so the device can wake up the system */
> - if (device_can_wakeup(dev))
> + if (device_may_wakeup(dev))
It's ok
> return 0;
>
> return usb_phy_roothub_exit(phy_roothub);
>
>
> Here are my obervations
> - if wakeup is disabled it works fine as expected, phy_exit() is called and I'm able to reach
> low power states.
>
> - if wakeup is enabled (/sys/bus/usb/device/usb2/power/wakeup), then hcd_bus_suspend() is never called
> and so phy_power_off won't be called either.
>
> This means that the device_may_wakeup() check is redundant. Sorry for suggesting this.
You maybe use a wrong device.
>
> This also means that wakeup is not enabled on Chunfeng's platform. Chunfeng, can you confirm this?
> What does /sys/bus/usb/device/usb<?>/power/wakeup say?
They are also "disabled" state;
I think we should use wakeup state of hcd controller, but not
usb_device's, please test it, thanks.

>
> Chunfeng sent a patch [1] to set shared_hcd->skip_phy_initialization for the mtk platform.
> Chunfeng, why did you need this patch?
>
> [1] - https://patchwork.kernel.org/patch/10298641/
>
> What options do we have now to fix the original issue?
>
> Chungfeng, can you set skip_phy_initialization for the hcd that has PHY's linked to it?
> Then usb_phy_roothub_*() driver will be a no-op for you. And we could revert to the original approach
> of doing phy_power_off() as well as phy_exit() during suspend.
>
> Alternatively, Martin, how about not relying on skip_phy_initialization flag but having default behaviour
> of no-op for the usb_phy_roothub_*() driver. As platforms migrate to it they can set a new
> flag in hcd to use it?

>
> >
> >>>>> - fix this in the PHY driver
> >>>>
> >>>> There is nothing to fix in the PHY driver. It is doing what it is supposed to do.
> >>> I actually wonder if phy_ops should have explicit suspend/resume support:
> >>> - assuming we define two new callbacks: .suspend and .resume
> >>> - the PHY framework could call .power_off by default if .suspend is not defined
> >>> - the PHY framework could call .power_on by default if .resume is not defined
> >>> - drivers could set .suspend and .resume on their own, allowing more
> >>> fine-grained control by for example *only* stopping the clock (but not
> >>> re-initializing the registers, etc.)
> >>>
> >>> @Roger: what do you think about this?
> >>> Kishon (the PHY framework maintainer) is also CC'ed - I would like to
> >>> hear his opinion too
> >>>
> >>>>> - somewhere else
> >>>>>
> >>>>>>> +}
> >>>>>>> +EXPORT_SYMBOL_GPL(usb_phy_roothub_power_off);
> >>>>>>> diff --git a/drivers/usb/core/phy.h b/drivers/usb/core/phy.h
> >>>>>>> new file mode 100644
> >>>>>>> index 000000000000..6fde59bfbff8
> >>>>>>> --- /dev/null
> >>>>>>> +++ b/drivers/usb/core/phy.h
> >>>>>>> @@ -0,0 +1,7 @@
> >>>>>>> +struct usb_phy_roothub;
> >>>>>>> +
> >>>>>>> +struct usb_phy_roothub *usb_phy_roothub_init(struct device *dev);
> >>>>>>> +int usb_phy_roothub_exit(struct usb_phy_roothub *phy_roothub);
> >>>>>>> +
> >>>>>>> +int usb_phy_roothub_power_on(struct usb_phy_roothub *phy_roothub);
> >>>>>>> +void usb_phy_roothub_power_off(struct usb_phy_roothub *phy_roothub);
> >>>>>>>
> >>>>>>
> >>>>
>
> >
> > [0] https://github.com/xdarklight/linux/commits/usb-phy-roothub-suspend-rfc-v1
> >
>