[PATCHv2 2/2] USB: host: ohci_at91: Stop/start USB PLL for all sleep modes

[Sylvain Rochet]

Disable/unprepare clocks without testing the sleep target_state, removed
the at91_suspend_entering_slow_clock() call (which is only a
target_state == PM_SUSPEND_MEM).

Other kind of suspend now benefit from the power save induced by this
PLL deactivation. The resume penalty is about 500 us, which is not
negligible but acceptable considering the amount of power we are saving.

Signed-off-by: Sylvain Rochet <sylvain.rochet at finsecur.com>
Reported-by: Boris Brezillon <boris.brezillon at free-electrons.com>
---
 drivers/usb/host/ohci-at91.c | 25 +++++++++++++------------
 1 file changed, 13 insertions(+), 12 deletions(-)

diff --git a/drivers/usb/host/ohci-at91.c b/drivers/usb/host/ohci-at91.c
index dc9e4e6..f0da734 100644
--- a/drivers/usb/host/ohci-at91.c
+++ b/drivers/usb/host/ohci-at91.c
@@ -49,6 +49,8 @@ extern int usb_disabled(void);
 
 static void at91_start_clock(void)
 {
+	if (clocked)
+		return;
 	if (IS_ENABLED(CONFIG_COMMON_CLK)) {
 		clk_set_rate(uclk, 48000000);
 		clk_prepare_enable(uclk);
@@ -61,6 +63,8 @@ static void at91_start_clock(void)
 
 static void at91_stop_clock(void)
 {
+	if (!clocked)
+		return;
 	clk_disable_unprepare(fclk);
 	clk_disable_unprepare(iclk);
 	clk_disable_unprepare(hclk);
@@ -615,16 +619,14 @@ ohci_hcd_at91_drv_suspend(struct platform_device *pdev, pm_message_t mesg)
 	 *
 	 * REVISIT: some boards will be able to turn VBUS off...
 	 */
-	if (at91_suspend_entering_slow_clock()) {
-		ohci->hc_control = ohci_readl(ohci, &ohci->regs->control);
-		ohci->hc_control &= OHCI_CTRL_RWC;
-		ohci_writel(ohci, ohci->hc_control, &ohci->regs->control);
-		ohci->rh_state = OHCI_RH_HALTED;
-
-		/* flush the writes */
-		(void) ohci_readl (ohci, &ohci->regs->control);
-		at91_stop_clock();
-	}
+	ohci->hc_control = ohci_readl(ohci, &ohci->regs->control);
+	ohci->hc_control &= OHCI_CTRL_RWC;
+	ohci_writel(ohci, ohci->hc_control, &ohci->regs->control);
+	ohci->rh_state = OHCI_RH_HALTED;
+
+	/* flush the writes */
+	(void) ohci_readl (ohci, &ohci->regs->control);
+	at91_stop_clock();
 
 	return ret;
 }
@@ -636,8 +638,7 @@ static int ohci_hcd_at91_drv_resume(struct platform_device *pdev)
 	if (device_may_wakeup(&pdev->dev))
 		disable_irq_wake(hcd->irq);
 
-	if (!clocked)
-		at91_start_clock();
+	at91_start_clock();
 
 	ohci_resume(hcd, false);
 	return 0;
-- 
2.1.4