[v2] Bluetooth: btusb: Reset port on cmd timeout

Commit Message

Abhishek Pandit-Subedi June 24, 2020, 6:11 p.m. UTC

QCA_ROME sometimes gets into a state where it is unresponsive to
commands. Since it doesn't have support for a reset gpio, reset the usb
port when this occurs instead.

Signed-off-by: Abhishek Pandit-Subedi <[e-mail]>
---
On Chromebooks with this chipset, we encountered cmd_timeout after
running suspend stress test for hundreds of iterations. Without
a recovery mechanism, continued cmd_timeout failures eventually caused
the suspend stress test to fail.

This change will just reset the port that the Bluetooth chip is on when
cmd_timeout is encountered. At the very least, the driver will unload
and stop affecting suspend. It doesn't seem to restore the BT controller
to a good state however (this still requires a power cycle).

Changes in v2:
- Renamed btusb_generic_usb_cmd_timeout to btusb_qca_cmd_timeout
- Updated commit note

 drivers/bluetooth/btusb.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

Comments

Marcel Holtmann June 24, 2020, 6:27 p.m. UTC | #1

Hi Abhishek,

> QCA_ROME sometimes gets into a state where it is unresponsive to
> commands. Since it doesn't have support for a reset gpio, reset the usb
> port when this occurs instead.
> 
> Signed-off-by: Abhishek Pandit-Subedi <[e-mail]>
> ---
> On Chromebooks with this chipset, we encountered cmd_timeout after
> running suspend stress test for hundreds of iterations. Without
> a recovery mechanism, continued cmd_timeout failures eventually caused
> the suspend stress test to fail.
> 
> This change will just reset the port that the Bluetooth chip is on when
> cmd_timeout is encountered. At the very least, the driver will unload
> and stop affecting suspend. It doesn't seem to restore the BT controller
> to a good state however (this still requires a power cycle).
> 
> Changes in v2:
> - Renamed btusb_generic_usb_cmd_timeout to btusb_qca_cmd_timeout
> - Updated commit note
> 
> drivers/bluetooth/btusb.c | 17 +++++++++++++++++
> 1 file changed, 17 insertions(+)

patch has been applied to bluetooth-next tree.

Regards

Marcel

Oliver Neukum June 25, 2020, 10:22 a.m. UTC | #2

Am Mittwoch, den 24.06.2020, 11:11 -0700 schrieb Abhishek Pandit-
Subedi:
> QCA_ROME sometimes gets into a state where it is unresponsive to
> commands. Since it doesn't have support for a reset gpio, reset the usb
> port when this occurs instead.

Hi,

on first glance this looks like an unbalanced PM reference. It is not
because the operation is suicidal, but this deserves a comment, unless
you want to get a note telling you that you caused an imbalance every
few weeks.

	Regards
		Oliver

Abhishek Pandit-Subedi June 25, 2020, 11:18 p.m. UTC | #3

Thanks for the heads up Oliver -- I will send a patch with a comment on this.

On Thu, Jun 25, 2020 at 3:22 AM Oliver Neukum <[e-mail]> wrote:
>
> Am Mittwoch, den 24.06.2020, 11:11 -0700 schrieb Abhishek Pandit-
> Subedi:
> > QCA_ROME sometimes gets into a state where it is unresponsive to
> > commands. Since it doesn't have support for a reset gpio, reset the usb
> > port when this occurs instead.
>
> Hi,
>
> on first glance this looks like an unbalanced PM reference. It is not
> because the operation is suicidal, but this deserves a comment, unless
> you want to get a note telling you that you caused an imbalance every
> few weeks.
>
>         Regards
>                 Oliver
>

Patch

diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c
index e42fdd625eb023..df46b2a34c1803 100644
--- a/drivers/bluetooth/btusb.c
+++ b/drivers/bluetooth/btusb.c
@@ -573,6 +573,22 @@  static void btusb_rtl_cmd_timeout(struct hci_dev *hdev)
 	gpiod_set_value_cansleep(reset_gpio, 0);
 }
 
+static void btusb_qca_cmd_timeout(struct hci_dev *hdev)
+{
+	struct btusb_data *data = hci_get_drvdata(hdev);
+	int err;
+
+	if (++data->cmd_timeout_cnt < 5)
+		return;
+
+	bt_dev_err(hdev, "Multiple cmd timeouts seen. Resetting usb device.");
+	err = usb_autopm_get_interface(data->intf);
+	if (!err)
+		usb_queue_reset_device(data->intf);
+	else
+		bt_dev_err(hdev, "Failed usb_autopm_get_interface with %d", err);
+}
+
 static inline void btusb_free_frags(struct btusb_data *data)
 {
 	unsigned long flags;
@@ -3964,6 +3980,7 @@  static int btusb_probe(struct usb_interface *intf,
 	if (id->driver_info & BTUSB_QCA_ROME) {
 		data->setup_on_usb = btusb_setup_qca;
 		hdev->set_bdaddr = btusb_set_bdaddr_ath3012;
+		hdev->cmd_timeout = btusb_qca_cmd_timeout;
 		set_bit(HCI_QUIRK_SIMULTANEOUS_DISCOVERY, &hdev->quirks);
 		btusb_check_needs_reset_resume(intf);
 	}