usb: chipidea: add wait vbus lower than OTGSC_BSV before role starts

When the gadget role starts, we need to make sure the vbus is lower
than OTGSC_BSV, or there will be an vbus interrupt since we use
B_SESSION_VALID as vbus interrupt to indicate connect and disconnect.
When the host role starts, it may not be useful to wait vbus to lower
than OTGSC_BSV, but it can indicate some hardware problems like the
vbus is still higher than OTGSC_BSV after we disconnect to host some
time later (5000 milliseconds currently), which is obvious not correct.

Tested-by: Marek Vasut <marex@denx.de>
Signed-off-by: Peter Chen <peter.chen@freescale.com>
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 4 insertions, 0 deletions

diff --git a/drivers/usb/chipidea/otg.c b/drivers/usb/chipidea/otg.c
index 7f37484ca362..39bd7ec8bf75 100644
--- a/drivers/usb/chipidea/otg.c
+++ b/drivers/usb/chipidea/otg.c
@@ -52,6 +52,7 @@ void ci_handle_vbus_change(struct ci_hdrc *ci)
 		usb_gadget_vbus_disconnect(&ci->gadget);
 }
 
+#define CI_VBUS_STABLE_TIMEOUT_MS 5000
 static void ci_handle_id_switch(struct ci_hdrc *ci)
 {
 	enum ci_role role = ci_otg_role(ci);
@@ -61,6 +62,9 @@ static void ci_handle_id_switch(struct ci_hdrc *ci)
 			ci_role(ci)->name, ci->roles[role]->name);
 
 		ci_role_stop(ci);
+		/* wait vbus lower than OTGSC_BSV */
+		hw_wait_reg(ci, OP_OTGSC, OTGSC_BSV, 0,
+				CI_VBUS_STABLE_TIMEOUT_MS);
 		ci_role_start(ci, role);
 	}
 }