From 9262c19d14c433a6a1ba25c3ff897cb89e412309 Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Tue, 20 May 2014 18:08:12 -0700 Subject: [PATCH] usb: disable port power control if not supported in wHubCharacteristics A hub indicates whether it supports per-port power control via the wHubCharacteristics field in its descriptor. If it is not supported a hub will still emulate ClearPortPower(PORT_POWER) requests by stopping the link state machine. However, since this does not save power do not bother suspending. This also consolidates support checks into a hub_is_port_power_switchable() helper. Acked-by: Alan Stern Signed-off-by: Dan Williams Signed-off-by: Greg Kroah-Hartman --- drivers/usb/core/hub.c | 8 ++------ drivers/usb/core/hub.h | 10 ++++++++++ drivers/usb/core/port.c | 13 ++++++++----- 3 files changed, 20 insertions(+), 11 deletions(-) diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c index 5f43c22ba787..77b91888abef 100644 --- a/drivers/usb/core/hub.c +++ b/drivers/usb/core/hub.c @@ -818,8 +818,6 @@ static unsigned hub_power_on(struct usb_hub *hub, bool do_delay) int port1; unsigned pgood_delay = hub->descriptor->bPwrOn2PwrGood * 2; unsigned delay; - u16 wHubCharacteristics = - le16_to_cpu(hub->descriptor->wHubCharacteristics); /* Enable power on each port. Some hubs have reserved values * of LPSM (> 2) in their descriptors, even though they are @@ -827,7 +825,7 @@ static unsigned hub_power_on(struct usb_hub *hub, bool do_delay) * but only emulate it. In all cases, the ports won't work * unless we send these messages to the hub. */ - if ((wHubCharacteristics & HUB_CHAR_LPSM) < 2) + if (hub_is_port_power_switchable(hub)) dev_dbg(hub->intfdev, "enabling power on all ports\n"); else dev_dbg(hub->intfdev, "trying to enable port power on " @@ -4417,8 +4415,6 @@ static void hub_port_connect_change(struct usb_hub *hub, int port1, struct usb_device *hdev = hub->hdev; struct device *hub_dev = hub->intfdev; struct usb_hcd *hcd = bus_to_hcd(hdev->bus); - unsigned wHubCharacteristics = - le16_to_cpu(hub->descriptor->wHubCharacteristics); struct usb_device *udev; int status, i; unsigned unit_load; @@ -4503,7 +4499,7 @@ static void hub_port_connect_change(struct usb_hub *hub, int port1, test_bit(port1, hub->removed_bits)) { /* maybe switch power back on (e.g. root hub was reset) */ - if ((wHubCharacteristics & HUB_CHAR_LPSM) < 2 + if (hub_is_port_power_switchable(hub) && !port_is_power_on(hub, portstatus)) set_port_feature(hdev, port1, USB_PORT_FEAT_POWER); diff --git a/drivers/usb/core/hub.h b/drivers/usb/core/hub.h index f9b521e60128..4bd72dd303d5 100644 --- a/drivers/usb/core/hub.h +++ b/drivers/usb/core/hub.h @@ -112,6 +112,16 @@ extern int hub_port_debounce(struct usb_hub *hub, int port1, extern int usb_clear_port_feature(struct usb_device *hdev, int port1, int feature); +static inline bool hub_is_port_power_switchable(struct usb_hub *hub) +{ + __le16 hcs; + + if (!hub) + return false; + hcs = hub->descriptor->wHubCharacteristics; + return (le16_to_cpu(hcs) & HUB_CHAR_LPSM) < HUB_CHAR_NO_LPSM; +} + static inline int hub_port_debounce_be_connected(struct usb_hub *hub, int port1) { diff --git a/drivers/usb/core/port.c b/drivers/usb/core/port.c index 37647e080599..168fa6ee3348 100644 --- a/drivers/usb/core/port.c +++ b/drivers/usb/core/port.c @@ -177,12 +177,15 @@ int usb_hub_create_port_device(struct usb_hub *hub, int port1) pm_runtime_set_active(&port_dev->dev); - /* It would be dangerous if user space couldn't - * prevent usb device from being powered off. So don't - * enable port runtime pm if failed to expose port's pm qos. + /* + * Do not enable port runtime pm if the hub does not support + * power switching. Also, userspace must have final say of + * whether a port is permitted to power-off. Do not enable + * runtime pm if we fail to expose pm_qos_no_power_off. */ - if (!dev_pm_qos_expose_flags(&port_dev->dev, - PM_QOS_FLAG_NO_POWER_OFF)) + if (hub_is_port_power_switchable(hub) + && dev_pm_qos_expose_flags(&port_dev->dev, + PM_QOS_FLAG_NO_POWER_OFF) == 0) pm_runtime_enable(&port_dev->dev); device_enable_async_suspend(&port_dev->dev); -- 2.45.2