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Commit 8643ff14 authored by Jack Pham's avatar Jack Pham
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usb: dwc3-msm: Disable clock gating always 



There is a known HW bug on the DWC3 MSM implementation that
causes the internal RAM clock to get stuck when entering low
power modes. The workaround for this is to disable internal
clock gating always. As the DWC3_GCTL register will get reset
when coming out of power collapse, make sure to save and
restore the value during suspend and resume.

Change-Id: Id5c7496fbc65f328c84e63bb0588c91fb226c1d7
Signed-off-by: default avatarJack Pham <jackp@codeaurora.org>
parent d602960e

drivers/usb/dwc3/dwc3-msm.c

+13 −0
Original line number Diff line number Diff line
@@ -202,6 +202,7 @@ struct dwc3_msm { 
#define MDWC3_PHY_REF_AND_CORECLK_OFF	\

			(MDWC3_PHY_REF_CLK_OFF | MDWC3_CORECLK_OFF)



	u32 gctl_val;

	u32 qscratch_ctl_val;

	dev_t ext_chg_dev;

	struct cdev ext_chg_cdev;
@@ -1144,6 +1145,13 @@ static void dwc3_msm_notify_event(struct dwc3 *dwc, unsigned event) 
		dwc->tx_fifo_size = mdwc->tx_fifo_size;

		break;

	case DWC3_CONTROLLER_POST_INITIALIZATION_EVENT:

		/*

		 * Workaround: Disable internal clock gating always, as there

		 * is a known HW bug that causes the internal RAM clock to get

		 * stuck when entering low power modes.

		 */

		dwc3_msm_write_reg_field(mdwc->base, DWC3_GCTL,

					DWC3_GCTL_DSBLCLKGTNG, 1);

		usb_phy_post_init(mdwc->ss_phy);

		break;

	case DWC3_CONTROLLER_CONNDONE_EVENT:
@@ -1702,6 +1710,9 @@ static int dwc3_msm_suspend(struct dwc3_msm *mdwc) 
	/* make sure above writes are completed before turning off clocks */

	wmb();



	/* Save value of GCTL to rewrite upon resume */

	mdwc->gctl_val = dwc3_msm_read_reg(mdwc->base, DWC3_GCTL);



	/* Perform controller power collapse */

	if (!host_bus_suspend && mdwc->power_collapse && !cable_connected) {

		mdwc->lpm_flags |= MDWC3_POWER_COLLAPSE;
@@ -1856,6 +1867,8 @@ static int dwc3_msm_resume(struct dwc3_msm *mdwc) 
		mdwc->lpm_flags &= ~MDWC3_POWER_COLLAPSE;

	}



	dwc3_msm_write_reg(mdwc->base, DWC3_GCTL, mdwc->gctl_val);



	atomic_set(&dwc->in_lpm, 0);



	msm_bam_notify_lpm_resume(DWC3_CTRL);