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Commit 23bafa2f authored by Manu Gautam's avatar Manu Gautam
Browse files

USB: phy-msm-usb: Avoid race b/w sm_work and set_suspend 



OTG's set_suspend routine is used by host controller (EHCI)
driver to suspend or resume USB OTG/PHY hardware from its
runtime suspend/resume callbacks. OTG set_suspend routine
uses sm_workqueue to put hardware in LPM (or suspend it).
As there is no synchronization between sm_work and
set_suspend, this results in both racing with each other.
Sometimes with fast back to back set_suspend calls, PHY LPM
state goes out of sync than what requested by host driver.
Fix this by flushing work from set_suspend to complete
event processing by sm_work.

CRs-fixed: 654489
Change-Id: I5e0bfa3bc6c12af23fd26b2496c7ee5b7fc1488e
Signed-off-by: default avatarManu Gautam <mgautam@codeaurora.org>
parent 1e733ca9

drivers/usb/phy/phy-msm-usb.c

+9 −1
Original line number Diff line number Diff line
@@ -786,6 +786,9 @@ static int msm_otg_set_suspend(struct usb_phy *phy, int suspend) 
	if (aca_enabled())

		return 0;



	pr_debug("%s(%d) in %s state\n", __func__, suspend,

				usb_otg_state_string(phy->state));



	/*

	 * UDC and HCD call usb_phy_set_suspend() to enter/exit LPM

	 * during bus suspend/resume.  Update the relevant state
@@ -801,8 +804,13 @@ static int msm_otg_set_suspend(struct usb_phy *phy, int suspend) 
		case OTG_STATE_A_HOST:

			pr_debug("host bus suspend\n");

			clear_bit(A_BUS_REQ, &motg->inputs);

			if (!atomic_read(&motg->in_lpm))

			if (!atomic_read(&motg->in_lpm)) {

				queue_work(system_nrt_wq, &motg->sm_work);

				/* Flush sm_work to avoid it race with

				 * subsequent calls of set_suspend.

				 */

				flush_work(&motg->sm_work);

			}

			break;

		case OTG_STATE_B_PERIPHERAL:

			pr_debug("peripheral bus suspend\n");