According to the dt-bindings there are some platforms, which have a
dedicated USB power domain for DWC2 IP core supply. If the power domain
is switched off during system suspend then all USB register will lose
their settings.
Use GUSBCFG_TOUTCAL as a canary to detect that the power domain has
been powered off during suspend. Since the GOTGCTL_CURMODE_HOST doesn't
match on all platform with the current mode, additionally backup
GINTSTS. This works reliable to decide which registers should be
restored.
Signed-off-by: Stefan Wahren <wahrenst@xxxxxxx>
---
drivers/usb/dwc2/core.c | 1 +
drivers/usb/dwc2/core.h | 2 ++
drivers/usb/dwc2/platform.c | 38 +++++++++++++++++++++++++++++++++++++
3 files changed, 41 insertions(+)
Hi, would be nice to get some feedback about the approach and
test results on other DWC2 platforms.
diff --git a/drivers/usb/dwc2/core.c b/drivers/usb/dwc2/core.c
index 9919ab725d54..c3d24312db0f 100644
--- a/drivers/usb/dwc2/core.c
+++ b/drivers/usb/dwc2/core.c
@@ -43,6 +43,7 @@ int dwc2_backup_global_registers(struct dwc2_hsotg *hsotg)
/* Backup global regs */
gr = &hsotg->gr_backup;
+ gr->gintsts = dwc2_readl(hsotg, GINTSTS);
gr->gotgctl = dwc2_readl(hsotg, GOTGCTL);
gr->gintmsk = dwc2_readl(hsotg, GINTMSK);
gr->gahbcfg = dwc2_readl(hsotg, GAHBCFG);
diff --git a/drivers/usb/dwc2/core.h b/drivers/usb/dwc2/core.h
index 81e8632f29ed..e65a74853bb0 100644
--- a/drivers/usb/dwc2/core.h
+++ b/drivers/usb/dwc2/core.h
@@ -667,6 +667,7 @@ struct dwc2_hw_params {
/**
* struct dwc2_gregs_backup - Holds global registers state before
* entering partial power down
+ * @gintsts: Backup of GINTSTS register
* @gotgctl: Backup of GOTGCTL register
* @gintmsk: Backup of GINTMSK register
* @gahbcfg: Backup of GAHBCFG register
@@ -683,6 +684,7 @@ struct dwc2_hw_params {
* @valid: True if registers values backuped.
*/
struct dwc2_gregs_backup {
+ u32 gintsts;
u32 gotgctl;
u32 gintmsk;
u32 gahbcfg;
diff --git a/drivers/usb/dwc2/platform.c b/drivers/usb/dwc2/platform.c
index 7b84416dfc2b..39e9064b6cfe 100644
--- a/drivers/usb/dwc2/platform.c
+++ b/drivers/usb/dwc2/platform.c
@@ -683,6 +683,14 @@ static int __maybe_unused dwc2_suspend(struct device *dev)
regulator_disable(dwc2->usb33d);
}
+ if (is_device_mode)
+ ret = dwc2_gadget_backup_critical_registers(dwc2);
+ else
+ ret = dwc2_host_backup_critical_registers(dwc2);
+
+ if (ret)
+ return ret;
+
if (dwc2->ll_hw_enabled &&
(is_device_mode || dwc2_host_can_poweroff_phy(dwc2))) {
ret = __dwc2_lowlevel_hw_disable(dwc2);
@@ -692,6 +700,24 @@ static int __maybe_unused dwc2_suspend(struct device *dev)
return ret;
}
+static int dwc2_restore_critical_registers(struct dwc2_hsotg *hsotg)
+{
+ struct dwc2_gregs_backup *gr;
+
+ gr = &hsotg->gr_backup;
+
+ if (!gr->valid) {
+ dev_err(hsotg->dev, "%s: no registers to restore\n",
+ __func__);
+ return -EINVAL;
+ }
+
+ if (gr->gintsts & GINTSTS_CURMODE_HOST)
+ return dwc2_host_restore_critical_registers(hsotg);
+
+ return dwc2_gadget_restore_critical_registers(hsotg);
+}
+
static int __maybe_unused dwc2_resume(struct device *dev)
{
struct dwc2_hsotg *dwc2 = dev_get_drvdata(dev);
@@ -704,6 +730,18 @@ static int __maybe_unused dwc2_resume(struct device *dev)
}
dwc2->phy_off_for_suspend = false;
+ /*
+ * During suspend it's possible that the power domain for the
+ * DWC2 controller is disabled and all register values get lost.
+ * In case the GUSBCFG register is not initialized, it's clear the
+ * registers must be restored.
+ */
+ if (!(dwc2_readl(dwc2, GUSBCFG) & GUSBCFG_TOUTCAL_MASK)) {
+ ret = dwc2_restore_critical_registers(dwc2);
+ if (ret)
+ return ret;
+ }
+
if (dwc2->params.activate_stm_id_vb_detection) {
unsigned long flags;
u32 ggpio, gotgctl;
--
2.34.1
