From 4d8a0a2c146a6dae81dde6d6cc40ae53f362e719 Mon Sep 17 00:00:00 2001 From: Sven Peter Date: Sun, 7 Nov 2021 11:21:20 +0100 Subject: [PATCH] usb: dwc3: Add role switch reset quirk for Apple DWC3 As mad as it sounds, the dwc3 controller present on the Apple M1 must be reset and reinitialized whenever a device is unplugged from the root port. The only reliable unplug/plug notification available comes from the USB PD controller through the role-switch infrastructure. This is required for at least two reasons: - The USB2 D+/D- lines are connected through a stateful eUSB2 repeater which in turn is controlled by a variant of the TI TPS6598x USB PD chip. When the USB PD controller detects a hotplug event it resets the eUSB2 repeater. Afterwards, no new device is recognized before the DWC3 core and PHY are reset as well. - It's possible to completely break the dwc3 controller by switching it to device mode and unplugging the cable at just the wrong time. Even a CORESOFTRESET is not enough to allow new devices again. The only workaround is to trigger a hard reset of the entire dwc3 core. Signed-off-by: Sven Peter --- drivers/usb/dwc3/core.c | 39 ++++++++++++++++++++++++++++++++++++--- drivers/usb/dwc3/core.h | 6 ++++++ drivers/usb/dwc3/drd.c | 7 +++++++ 3 files changed, 49 insertions(+), 3 deletions(-) diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c index f4c09951b517..b037415bccca 100644 --- a/drivers/usb/dwc3/core.c +++ b/drivers/usb/dwc3/core.c @@ -116,6 +116,8 @@ void dwc3_set_prtcap(struct dwc3 *dwc, u32 mode) } static int dwc3_core_soft_reset(struct dwc3 *dwc); +static void dwc3_core_exit(struct dwc3 *dwc); +static int dwc3_core_init_for_resume(struct dwc3 *dwc); static void __dwc3_set_mode(struct work_struct *work) { @@ -131,10 +133,11 @@ static void __dwc3_set_mode(struct work_struct *work) if (dwc->current_dr_role == DWC3_GCTL_PRTCAP_OTG) dwc3_otg_update(dwc, 0); - if (!dwc->desired_dr_role) + if (!dwc->desired_dr_role && !dwc->role_switch_reset_quirk) goto out; - if (dwc->desired_dr_role == dwc->current_dr_role) + if (dwc->desired_dr_role == dwc->current_dr_role && + !dwc->role_switch_reset_quirk) goto out; if (dwc->desired_dr_role == DWC3_GCTL_PRTCAP_OTG && dwc->edev) @@ -159,6 +162,34 @@ static void __dwc3_set_mode(struct work_struct *work) break; } + if (dwc->role_switch_reset_quirk) { + if (dwc->current_dr_role) { + dwc->current_dr_role = 0; + dwc3_core_exit(dwc); + } + + if (dwc->desired_dr_role) { + /* + * the first call to __dwc3_set_mode comes from + * dwc3_drd_init. In that case dwc3_core_init has been + * called but dwc->current_dr_role is zero such that + * we must not reinitialize the core again here. + */ + if (dwc->role_switch_reset_quirk_initialized) { + ret = dwc3_core_init_for_resume(dwc); + if (ret) { + dev_err(dwc->dev, + "failed to reinitialize core\n"); + goto out; + } + } + + dwc->role_switch_reset_quirk_initialized = 1; + } else { + goto out; + } + } + /* For DRD host or device mode only */ if (dwc->desired_dr_role != DWC3_GCTL_PRTCAP_OTG) { reg = dwc3_readl(dwc->regs, DWC3_GCTL); @@ -1617,6 +1648,8 @@ static int dwc3_probe(struct platform_device *pdev) else dwc->num_clks = ret; + if (of_device_is_compatible(dev->of_node, "apple,dwc3")) + dwc->role_switch_reset_quirk = true; } ret = reset_control_deassert(dwc->reset); @@ -1746,7 +1779,6 @@ static int dwc3_remove(struct platform_device *pdev) return 0; } -#ifdef CONFIG_PM static int dwc3_core_init_for_resume(struct dwc3 *dwc) { int ret; @@ -1773,6 +1805,7 @@ static int dwc3_core_init_for_resume(struct dwc3 *dwc) return ret; } +#ifdef CONFIG_PM static int dwc3_suspend_common(struct dwc3 *dwc, pm_message_t msg) { unsigned long flags; diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h index e1cc3f7398fb..7df0dc2dcefc 100644 --- a/drivers/usb/dwc3/core.h +++ b/drivers/usb/dwc3/core.h @@ -1096,6 +1096,9 @@ struct dwc3_scratchpad_array { * 3 - Reserved * @dis_metastability_quirk: set to disable metastability quirk. * @dis_split_quirk: set to disable split boundary. + * @role_switch_reset_quirk: set to force reinitialization after any role switch + * @role_switch_reset_quirk_initialized: set to true after the first role switch + * which is triggered from dwc3_drd_init directly * @imod_interval: set the interrupt moderation interval in 250ns * increments or 0 to disable. * @max_cfg_eps: current max number of IN eps used across all USB configs. @@ -1309,6 +1312,9 @@ struct dwc3 { unsigned dis_split_quirk:1; unsigned async_callbacks:1; + unsigned role_switch_reset_quirk:1; + unsigned role_switch_reset_quirk_initialized:1; + u16 imod_interval; int max_cfg_eps; diff --git a/drivers/usb/dwc3/drd.c b/drivers/usb/dwc3/drd.c index d7f76835137f..403e88a72f0e 100644 --- a/drivers/usb/dwc3/drd.c +++ b/drivers/usb/dwc3/drd.c @@ -506,6 +506,9 @@ static int dwc3_usb_role_switch_set(struct usb_role_switch *sw, break; } + if (dwc->role_switch_reset_quirk && role == USB_ROLE_NONE) + mode = 0; + dwc3_set_mode(dwc, mode); return 0; } @@ -534,6 +537,10 @@ static enum usb_role dwc3_usb_role_switch_get(struct usb_role_switch *sw) role = USB_ROLE_DEVICE; break; } + + if (dwc->role_switch_reset_quirk && !dwc->current_dr_role) + role = USB_ROLE_NONE; + spin_unlock_irqrestore(&dwc->lock, flags); return role; } -- 2.34.1