[PATCH 06/10] usb: chipidea: msm: keep the glue device runtime-active

[Dmitry Baryshkov]

The msm chipidea glue enables runtime PM with pm_runtime_no_callbacks()
and nothing pinning it active. Right after a successful probe the
driver core's pm_request_idle() runtime-suspends the glue (the ci core
child has runtime PM disabled, so it does not hold its parent), and
when the glue sits in a power domain - the HSIC instances live in the
USB_HS_HSIC GDSC on msm8974 - genpd then powers the domain off
underneath the running controller. The EHCI register file reads back
zeroes, an onboard hub's connect is never seen, and subsequent bus
accesses into the unpowered block wedge the interconnect, eventually
taking the whole SoC down.

Pin the glue runtime-active so the domain stays powered for the
lifetime of the controller. Proper low-power handling can later be
built on the child's runtime PM together with the HSIC wakeup
interrupt.

Fixes: 2d0cdcc5a0e4 ("USB: gadget: Implement runtime PM for MSM bus glue driver")
Assisted-by: Claude:claude-fable-5
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxxxxxxxx>
---
 drivers/usb/chipidea/ci_hdrc_msm.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/usb/chipidea/ci_hdrc_msm.c b/drivers/usb/chipidea/ci_hdrc_msm.c
index e28ea87f9898..9a9410a814e5 100644
--- a/drivers/usb/chipidea/ci_hdrc_msm.c
+++ b/drivers/usb/chipidea/ci_hdrc_msm.c
@@ -276,7 +276,13 @@ static int ci_hdrc_msm_probe(struct platform_device *pdev)
 			dev_warn(&pdev->dev, "no wakeup interrupt: %d\n", ret);
 	}
 
+	/*
+	 * The glue owns the controller's power domain (the HSIC instances sit
+	 * in a GDSC): if it runtime-suspends, the domain is powered off
+	 * underneath the running controller. Pin it active.
+	 */
 	pm_runtime_set_active(&pdev->dev);
+	pm_runtime_get_noresume(&pdev->dev);
 	pm_runtime_no_callbacks(&pdev->dev);
 	pm_runtime_enable(&pdev->dev);
 
@@ -294,6 +300,7 @@ static void ci_hdrc_msm_remove(struct platform_device *pdev)
 	struct ci_hdrc_msm *ci = platform_get_drvdata(pdev);
 
 	pm_runtime_disable(&pdev->dev);
+	pm_runtime_put_noidle(&pdev->dev);
 	dev_pm_clear_wake_irq(&ci->ci->dev);
 	ci_hdrc_remove_device(ci->ci);
 	clk_disable_unprepare(ci->iface_clk);

-- 
2.47.3