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

Roger Quadros
2018-03-16T14:32:29Z

+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@googlemail.com>
> Tested-by: Yixun Lan <yixun.lan@amlogic.com>
> Cc: Neil Armstrong <narmstrong@baylibre.com>
> Cc: Chunfeng Yun <chunfeng.yun@mediatek.com>

This patch is breaking low power cases on TI SoCs when USB is in host mode.
I'll explain why below.

> ---
> 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@googlemail.com>
> + */
> +
> +#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().

> + 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().

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.

> +}
> +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);
>

The following patch fixes the issue for me. Let me know what you think and I can post it officially.

diff --git a/drivers/usb/core/phy.c b/drivers/usb/core/phy.c
index 09b7c43..23232d3 100644
--- a/drivers/usb/core/phy.c
+++ b/drivers/usb/core/phy.c
@@ -59,8 +59,6 @@ static int usb_phy_roothub_add_phy(struct device *dev, int index,
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",
@@ -75,25 +73,10 @@ struct usb_phy_roothub *usb_phy_roothub_init(struct device *dev)
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);
- if (err)
- goto err_exit_phys;
+ return ERR_PTR(err);
}

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);

@@ -106,13 +89,8 @@ int usb_phy_roothub_exit(struct usb_phy_roothub *phy_roothub)
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;
- }
+ /* TODO: usb_phy_roothub_del_phy */
+ /* TODO: usb_phy_roothub_free */

return ret;
}
@@ -130,16 +108,23 @@ int usb_phy_roothub_power_on(struct usb_phy_roothub *phy_roothub)
head = &phy_roothub->list;

list_for_each_entry(roothub_entry, head, list) {
- err = phy_power_on(roothub_entry->phy);
+ err = phy_init(roothub_entry->phy);
if (err)
goto err_out;
+ err = phy_power_on(roothub_entry->phy);
+ if (err) {
+ phy_exit(roothub_entry->phy);
+ goto err_out;
+ }
}

return 0;

err_out:
- list_for_each_entry_continue_reverse(roothub_entry, head, list)
+ list_for_each_entry_continue_reverse(roothub_entry, head, list) {
phy_power_off(roothub_entry->phy);
+ phy_exit(roothub_entry->phy);
+ }

return err;
}
@@ -152,7 +137,9 @@ void usb_phy_roothub_power_off(struct usb_phy_roothub *phy_roothub)
if (!phy_roothub)
return;

- list_for_each_entry_reverse(roothub_entry, &phy_roothub->list, list)
+ list_for_each_entry_reverse(roothub_entry, &phy_roothub->list, list) {
phy_power_off(roothub_entry->phy);
+ phy_exit(roothub_entry->phy);
+ }
}
EXPORT_SYMBOL_GPL(usb_phy_roothub_power_off);

--
cheers,
-roger

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