From 6d1d051330ee096f575523647fbd8ffe703600b5 Mon Sep 17 00:00:00 2001 From: Sarah Sharp Date: Tue, 3 Jul 2012 22:49:04 -0700 Subject: USB: Fix LPM disable/enable during device reset. The USB 3.0 specification says that sending a Set Feature or Clear Feature for U1/U2 Enable is not a valid request when the device is in the Default or Addressed state. It is only valid when the device is in the Configured state. The original LPM patch attempted to disable LPM after the device had been reset by hub_port_init(), before it had the configuration reinstalled. The TI hub I tested with did not fail the Clear Feature U1/U2 Enable request that khubd sent while it was in the addressed state, which is why I didn't catch it. Move the LPM disable before the device reset, so that we can send the Clear Feature U1/U2 Enable successfully, and balance the LPM disable count. Also delete any calls to usb_enable_lpm() on error paths that lead to re-enumeration. The calls will fail because the device isn't configured, and it's not useful to balance the LPM disable count because the usb_device is about to be destroyed before re-enumeration. Fix the early exit path ("done" label) to call usb_enable_lpm() to balance the LPM disable count. Note that calling usb_reset_and_verify_device() with an unconfigured device may fail on the first call to usb_disable_lpm(). That's because the LPM disable count is initialized to 0 (LPM enabled), and usb_disable_lpm() will attempt to send a Clear Feature U1/U2 request to a device in the Addressed state. The next patch will fix that. This commit should be backported to kernels as old as 3.5, that contain the commit 8306095fd2c1100e8244c09bf560f97aca5a311d "USB: Disable USB 3.0 LPM in critical sections." Signed-off-by: Sarah Sharp Cc: stable@vger.kernel.org --- drivers/usb/core/hub.c | 26 ++++++++++++-------------- 1 file changed, 12 insertions(+), 14 deletions(-) (limited to 'drivers/usb/core/hub.c') diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c index 4cc8dc96940..5c31d2c2f95 100644 --- a/drivers/usb/core/hub.c +++ b/drivers/usb/core/hub.c @@ -4673,6 +4673,16 @@ static int usb_reset_and_verify_device(struct usb_device *udev) } parent_hub = hdev_to_hub(parent_hdev); + /* Disable LPM while we reset the device and reinstall the alt settings. + * Device-initiated LPM settings, and system exit latency settings are + * cleared when the device is reset, so we have to set them up again. + */ + ret = usb_unlocked_disable_lpm(udev); + if (ret) { + dev_err(&udev->dev, "%s Failed to disable LPM\n.", __func__); + goto re_enumerate; + } + set_bit(port1, parent_hub->busy_bits); for (i = 0; i < SET_CONFIG_TRIES; ++i) { @@ -4700,22 +4710,11 @@ static int usb_reset_and_verify_device(struct usb_device *udev) goto done; mutex_lock(hcd->bandwidth_mutex); - /* Disable LPM while we reset the device and reinstall the alt settings. - * Device-initiated LPM settings, and system exit latency settings are - * cleared when the device is reset, so we have to set them up again. - */ - ret = usb_disable_lpm(udev); - if (ret) { - dev_err(&udev->dev, "%s Failed to disable LPM\n.", __func__); - mutex_unlock(hcd->bandwidth_mutex); - goto done; - } ret = usb_hcd_alloc_bandwidth(udev, udev->actconfig, NULL, NULL); if (ret < 0) { dev_warn(&udev->dev, "Busted HC? Not enough HCD resources for " "old configuration.\n"); - usb_enable_lpm(udev); mutex_unlock(hcd->bandwidth_mutex); goto re_enumerate; } @@ -4727,7 +4726,6 @@ static int usb_reset_and_verify_device(struct usb_device *udev) dev_err(&udev->dev, "can't restore configuration #%d (error=%d)\n", udev->actconfig->desc.bConfigurationValue, ret); - usb_enable_lpm(udev); mutex_unlock(hcd->bandwidth_mutex); goto re_enumerate; } @@ -4766,17 +4764,17 @@ static int usb_reset_and_verify_device(struct usb_device *udev) desc->bInterfaceNumber, desc->bAlternateSetting, ret); - usb_unlocked_enable_lpm(udev); goto re_enumerate; } } +done: /* Now that the alt settings are re-installed, enable LPM. */ usb_unlocked_enable_lpm(udev); -done: return 0; re_enumerate: + /* LPM state doesn't matter when we're about to destroy the device. */ hub_port_logical_disconnect(parent_hub, port1); return -ENODEV; } -- cgit v1.2.3 From f74631e3426474183389e55f703797bd965cd356 Mon Sep 17 00:00:00 2001 From: Sarah Sharp Date: Mon, 25 Jun 2012 12:08:08 -0700 Subject: USB: Enable Latency Tolerance Messaging (LTM). USB 3.0 devices may optionally support a new feature called Latency Tolerance Messaging. If both the xHCI host controller and the device support LTM, it should be turned on in order to give the system hardware a better clue about the latency tolerance values of its PCI devices. Once a Set Feature request to enable LTM is received, the USB 3.0 device will begin to send LTM updates as its buffers fill or empty, and it can tolerate more or less latency. The USB 3.0 spec, section C.4.2 says that LTM should be disabled just before the device is placed into suspend. Then the device will send an updated LTM notification, so that the system doesn't think it should remain in an active state in order to satisfy the latency requirements of the suspended device. The Set and Clear Feature LTM enable command can only be sent to a configured device. The device will respond with an error if that command is sent while it is in the Default or Addressed state. Make sure to check udev->actconfig in usb_enable_ltm() and usb_disable_ltm(), and don't send those commands when the device is unconfigured. LTM should be enabled once a new configuration is installed in usb_set_configuration(). If we end up sending duplicate Set Feature LTM Enable commands on a switch from one installed configuration to another configuration, that should be harmless. Make sure that LTM is disabled before the device is unconfigured in usb_disable_device(). If no drivers are bound to the device, it doesn't make sense to allow the device to control the latency tolerance of the xHCI host controller. Signed-off-by: Sarah Sharp --- drivers/usb/core/hub.c | 87 ++++++++++++++++++++++++++++++++++++++++++++++---- 1 file changed, 81 insertions(+), 6 deletions(-) (limited to 'drivers/usb/core/hub.c') diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c index 5c31d2c2f95..b5bd6bd8fd1 100644 --- a/drivers/usb/core/hub.c +++ b/drivers/usb/core/hub.c @@ -2610,6 +2610,57 @@ static int check_port_resume_type(struct usb_device *udev, return status; } +static bool usb_device_supports_ltm(struct usb_device *udev) +{ + if (udev->speed != USB_SPEED_SUPER || !udev->bos || !udev->bos->ss_cap) + return false; + return udev->bos->ss_cap->bmAttributes & USB_LTM_SUPPORT; +} + +int usb_disable_ltm(struct usb_device *udev) +{ + struct usb_hcd *hcd = bus_to_hcd(udev->bus); + + /* Check if the roothub and device supports LTM. */ + if (!usb_device_supports_ltm(hcd->self.root_hub) || + !usb_device_supports_ltm(udev)) + return 0; + + /* Clear Feature LTM Enable can only be sent if the device is + * configured. + */ + if (!udev->actconfig) + return 0; + + return usb_control_msg(udev, usb_sndctrlpipe(udev, 0), + USB_REQ_CLEAR_FEATURE, USB_RECIP_DEVICE, + USB_DEVICE_LTM_ENABLE, 0, NULL, 0, + USB_CTRL_SET_TIMEOUT); +} +EXPORT_SYMBOL_GPL(usb_disable_ltm); + +void usb_enable_ltm(struct usb_device *udev) +{ + struct usb_hcd *hcd = bus_to_hcd(udev->bus); + + /* Check if the roothub and device supports LTM. */ + if (!usb_device_supports_ltm(hcd->self.root_hub) || + !usb_device_supports_ltm(udev)) + return; + + /* Set Feature LTM Enable can only be sent if the device is + * configured. + */ + if (!udev->actconfig) + return; + + usb_control_msg(udev, usb_sndctrlpipe(udev, 0), + USB_REQ_SET_FEATURE, USB_RECIP_DEVICE, + USB_DEVICE_LTM_ENABLE, 0, NULL, 0, + USB_CTRL_SET_TIMEOUT); +} +EXPORT_SYMBOL_GPL(usb_enable_ltm); + #ifdef CONFIG_USB_SUSPEND /* @@ -2705,6 +2756,11 @@ int usb_port_suspend(struct usb_device *udev, pm_message_t msg) if (udev->usb2_hw_lpm_enabled == 1) usb_set_usb2_hardware_lpm(udev, 0); + if (usb_disable_ltm(udev)) { + dev_err(&udev->dev, "%s Failed to disable LTM before suspend\n.", + __func__); + return -ENOMEM; + } if (usb_unlocked_disable_lpm(udev)) { dev_err(&udev->dev, "%s Failed to disable LPM before suspend\n.", __func__); @@ -2734,7 +2790,8 @@ int usb_port_suspend(struct usb_device *udev, pm_message_t msg) if (udev->usb2_hw_lpm_capable == 1) usb_set_usb2_hardware_lpm(udev, 1); - /* Try to enable USB3 LPM again */ + /* Try to enable USB3 LTM and LPM again */ + usb_enable_ltm(udev); usb_unlocked_enable_lpm(udev); /* System sleep transitions should never fail */ @@ -2935,7 +2992,8 @@ int usb_port_resume(struct usb_device *udev, pm_message_t msg) if (udev->usb2_hw_lpm_capable == 1) usb_set_usb2_hardware_lpm(udev, 1); - /* Try to enable USB3 LPM */ + /* Try to enable USB3 LTM and LPM */ + usb_enable_ltm(udev); usb_unlocked_enable_lpm(udev); } @@ -3488,6 +3546,15 @@ EXPORT_SYMBOL_GPL(usb_unlocked_disable_lpm); void usb_unlocked_enable_lpm(struct usb_device *udev) { } EXPORT_SYMBOL_GPL(usb_unlocked_enable_lpm); + +int usb_disable_ltm(struct usb_device *udev) +{ + return 0; +} +EXPORT_SYMBOL_GPL(usb_disable_ltm); + +void usb_enable_ltm(struct usb_device *udev) { } +EXPORT_SYMBOL_GPL(usb_enable_ltm); #endif @@ -4673,15 +4740,22 @@ static int usb_reset_and_verify_device(struct usb_device *udev) } parent_hub = hdev_to_hub(parent_hdev); - /* Disable LPM while we reset the device and reinstall the alt settings. - * Device-initiated LPM settings, and system exit latency settings are - * cleared when the device is reset, so we have to set them up again. + /* Disable LPM and LTM while we reset the device and reinstall the alt + * settings. Device-initiated LPM settings, and system exit latency + * settings are cleared when the device is reset, so we have to set + * them up again. */ ret = usb_unlocked_disable_lpm(udev); if (ret) { dev_err(&udev->dev, "%s Failed to disable LPM\n.", __func__); goto re_enumerate; } + ret = usb_disable_ltm(udev); + if (ret) { + dev_err(&udev->dev, "%s Failed to disable LTM\n.", + __func__); + goto re_enumerate; + } set_bit(port1, parent_hub->busy_bits); for (i = 0; i < SET_CONFIG_TRIES; ++i) { @@ -4769,8 +4843,9 @@ static int usb_reset_and_verify_device(struct usb_device *udev) } done: - /* Now that the alt settings are re-installed, enable LPM. */ + /* Now that the alt settings are re-installed, enable LTM and LPM. */ usb_unlocked_enable_lpm(udev); + usb_enable_ltm(udev); return 0; re_enumerate: -- cgit v1.2.3 From 024f117c2f3c4bb5df6e6696b709e0f3ed7e5dbb Mon Sep 17 00:00:00 2001 From: Sarah Sharp Date: Thu, 5 Jul 2012 17:17:24 -0700 Subject: USB: Add a sysfs file to show LTM capabilities. USB 3.0 devices can optionally support Latency Tolerance Messaging (LTM). Add a new sysfs file in the device directory to show whether a device is LTM capable. This file will be present for both USB 2.0 and USB 3.0 devices. Signed-off-by: Sarah Sharp --- drivers/usb/core/hub.c | 7 ------- 1 file changed, 7 deletions(-) (limited to 'drivers/usb/core/hub.c') diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c index b5bd6bd8fd1..d739f966b5a 100644 --- a/drivers/usb/core/hub.c +++ b/drivers/usb/core/hub.c @@ -2610,13 +2610,6 @@ static int check_port_resume_type(struct usb_device *udev, return status; } -static bool usb_device_supports_ltm(struct usb_device *udev) -{ - if (udev->speed != USB_SPEED_SUPER || !udev->bos || !udev->bos->ss_cap) - return false; - return udev->bos->ss_cap->bmAttributes & USB_LTM_SUPPORT; -} - int usb_disable_ltm(struct usb_device *udev) { struct usb_hcd *hcd = bus_to_hcd(udev->bus); -- cgit v1.2.3