usb: dwc2: Skip clock gating on Samsung SoCs

Commit 0112b7ce68ea ("usb: dwc2: Update dwc2_handle_usb_suspend_intr
function.") changed the way the driver handles power down modes in a such
way that it uses clock gating when no other power down mode is available.

This however doesn't work well on the DWC2 implementation used on the
Samsung SoCs. When a clock gating is enabled, system hangs. It looks that
the proper clock gating requires some additional glue code in the shared
USB2 PHY and/or Samsung glue code for the DWC2. To restore driver
operation on the Samsung SoCs simply skip enabling clock gating mode
until one finds what is really needed to make it working reliably.

Fixes: 0112b7ce68ea ("usb: dwc2: Update dwc2_handle_usb_suspend_intr function.")
Cc: stable <stable@vger.kernel.org>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/20210716050127.4406-1-m.szyprowski@samsung.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/dwc2/core.h b/drivers/usb/dwc2/core.h
index ab6b815e0089ca1196fb6bf6911387154fc24bf1..483de2bbfaabe3ca1843cb3872afbb3f34a67b73 100644 (file)
--- a/drivers/usb/dwc2/core.h
+++ b/drivers/usb/dwc2/core.h
@@ -383,6 +383,9 @@ enum dwc2_ep0_state {
  *                     0 - No (default)
  *                     1 - Partial power down
  *                     2 - Hibernation
+ * @no_clock_gating:   Specifies whether to avoid clock gating feature.
+ *                     0 - No (use clock gating)
+ *                     1 - Yes (avoid it)
  * @lpm:               Enable LPM support.
  *                     0 - No
  *                     1 - Yes
@@ -480,6 +483,7 @@ struct dwc2_core_params {
 #define DWC2_POWER_DOWN_PARAM_NONE             0
 #define DWC2_POWER_DOWN_PARAM_PARTIAL          1
 #define DWC2_POWER_DOWN_PARAM_HIBERNATION      2
+       bool no_clock_gating;
 
        bool lpm;
        bool lpm_clock_gating;

diff --git a/drivers/usb/dwc2/core_intr.c b/drivers/usb/dwc2/core_intr.c
index a5ab03808da69fec436b2a1c1fa74d459a334295..a5c52b237e723753e9574dfe7236d0a445cf06cb 100644 (file)
--- a/drivers/usb/dwc2/core_intr.c
+++ b/drivers/usb/dwc2/core_intr.c
@@ -556,7 +556,8 @@ static void dwc2_handle_usb_suspend_intr(struct dwc2_hsotg *hsotg)
                                 * If neither hibernation nor partial power down are supported,
                                 * clock gating is used to save power.
                                 */
-                               dwc2_gadget_enter_clock_gating(hsotg);
+                               if (!hsotg->params.no_clock_gating)
+                                       dwc2_gadget_enter_clock_gating(hsotg);
                        }
 
                        /*

diff --git a/drivers/usb/dwc2/hcd.c b/drivers/usb/dwc2/hcd.c
index 035d4911a3c324d81d742dc91c775444fde42164..2a7828971d0564743e7caa933ad485c8eeb5b299 100644 (file)
--- a/drivers/usb/dwc2/hcd.c
+++ b/drivers/usb/dwc2/hcd.c
@@ -3338,7 +3338,8 @@ int dwc2_port_suspend(struct dwc2_hsotg *hsotg, u16 windex)
                 * If not hibernation nor partial power down are supported,
                 * clock gating is used to save power.
                 */
-               dwc2_host_enter_clock_gating(hsotg);
+               if (!hsotg->params.no_clock_gating)
+                       dwc2_host_enter_clock_gating(hsotg);
                break;
        }
 
@@ -4402,7 +4403,8 @@ static int _dwc2_hcd_suspend(struct usb_hcd *hcd)
                 * If not hibernation nor partial power down are supported,
                 * clock gating is used to save power.
                 */
-               dwc2_host_enter_clock_gating(hsotg);
+               if (!hsotg->params.no_clock_gating)
+                       dwc2_host_enter_clock_gating(hsotg);
 
                /* After entering suspend, hardware is not accessible */
                clear_bit(HCD_FLAG_HW_ACCESSIBLE, &hcd->flags);

diff --git a/drivers/usb/dwc2/params.c b/drivers/usb/dwc2/params.c
index 67c5eb1402325a219e5114923eed480c155cd4ee..59e119345994756166a4a4d4ef44bfd0c6302d03 100644 (file)
--- a/drivers/usb/dwc2/params.c
+++ b/drivers/usb/dwc2/params.c
@@ -76,6 +76,7 @@ static void dwc2_set_s3c6400_params(struct dwc2_hsotg *hsotg)
        struct dwc2_core_params *p = &hsotg->params;
 
        p->power_down = DWC2_POWER_DOWN_PARAM_NONE;
+       p->no_clock_gating = true;
        p->phy_utmi_width = 8;
 }