From 8afa408cba5c474696df6307a64b1c612bbcadbc Mon Sep 17 00:00:00 2001 From: Sarah Sharp Date: Mon, 23 Apr 2012 10:08:51 -0700 Subject: [PATCH] USB: Allow drivers to disable hub-initiated LPM. USB 3.0 Link Power Management (LPM) is designed to allow individual links in the bus to go into lower power states. There are two ways a link can enter a lower power state: 1. Device-initiated LPM. When a USB device decides it can go into a lower power link state, it sends a message to the parent hub, telling it to go into either U1 or U2. Device-initiated LPM is good for devices that send data to the host, like communications devices. 2. Hub-initiated LPM. After the link has been idle for a specific amount of time, the parent hub will request that the child go into a lower power state. The child can refuse that request. For example, a USB modem may want to refuse the LPM request if it is in the middle of receiving a text message. Hub-initiated LPM is good for devices where only the host initiates the data transfer, like USB printers or USB mass storage devices. Links will be automatically placed into higher power states by the USB hubs and roothubs whenever the host starts a USB transmission. Introduce a new usb_driver flag, disable_hub_initiated_lpm, that allows drivers to disable hub-initiated LPM. Signed-off-by: Sarah Sharp Cc: Marcel Holtmann Cc: Gustavo Padovan Cc: Johan Hedberg Cc: Hansjoerg Lipp Cc: Tilman Schmidt Cc: Karsten Keil Cc: Oliver Neukum Cc: Peter Korsgaard Cc: Jan Dumon Cc: Petko Manolov Cc: Steve Glendinning Cc: "John W. Linville" Cc: Kalle Valo Cc: "Luis R. Rodriguez" Cc: Jouni Malinen Cc: Vasanthakumar Thiagarajan Cc: Senthil Balasubramanian Cc: Christian Lamparter Cc: Brett Rudley Cc: Roland Vossen Cc: Arend van Spriel Cc: "Franky (Zhenhui) Lin" Cc: Kan Yan Cc: Dan Williams Cc: Jussi Kivilinna Cc: Ivo van Doorn Cc: Gertjan van Wingerde Cc: Helmut Schaa Cc: Herton Ronaldo Krzesinski Cc: Hin-Tak Leung Cc: Larry Finger Cc: Chaoming Li Cc: Daniel Drake Cc: Ulrich Kunitz Cc: linux-bluetooth@vger.kernel.org Cc: gigaset307x-common@lists.sourceforge.net Cc: netdev@vger.kernel.org Cc: linux-usb@vger.kernel.org Cc: linux-wireless@vger.kernel.org Cc: ath9k-devel@lists.ath9k.org Cc: libertas-dev@lists.infradead.org Cc: users@rt2x00.serialmonkey.com --- include/linux/usb.h | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/include/linux/usb.h b/include/linux/usb.h index e6c815590fdd..22e7b53123ef 100644 --- a/include/linux/usb.h +++ b/include/linux/usb.h @@ -879,6 +879,9 @@ struct usbdrv_wrap { * for interfaces bound to this driver. * @soft_unbind: if set to 1, the USB core will not kill URBs and disable * endpoints before calling the driver's disconnect method. + * @disable_hub_initiated_lpm: if set to 0, the USB core will not allow hubs + * to initiate lower power link state transitions when an idle timeout + * occurs. Device-initiated USB 3.0 link PM will still be allowed. * * USB interface drivers must provide a name, probe() and disconnect() * methods, and an id_table. Other driver fields are optional. @@ -919,6 +922,7 @@ struct usb_driver { struct usbdrv_wrap drvwrap; unsigned int no_dynamic_id:1; unsigned int supports_autosuspend:1; + unsigned int disable_hub_initiated_lpm:1; unsigned int soft_unbind:1; }; #define to_usb_driver(d) container_of(d, struct usb_driver, drvwrap.driver) -- 2.20.1