Hi,
On 11/23/20 11:13 AM, Hans de Goede wrote:
> With the recent btusb change to detect and deal with more fake CSR
> controllers, I decided to see if one of the fakes which I have
> lying around would now work.
>
> After much experimentation I came to the conclusion that it works, if I
> have autosuspend enabled initially and then disable it after the device
> has suspended at least once. Yes this is very weird, but I've tried many
> things, like manually clearing the remote-wakeup feature. Doing a
> runtime-resume + runtime suspend is the only way to get the receiver
> to actually report received data (and/or pairing info) through its
> bulk rx endpoint.
>
> But the funkyness of the bulk-endpoint does not stop there, I mainly
> found out about this problem, because with autosuspend enabled
> (which usually ensures the suspend at least once condition is met),
> the receiver stops reporting received data through its bulk rx endpoint
> as soon as autosuspend kicks in. So I initially just disabled
> autosuspend, but then the receiver does not work at all.
>
> This was with a fake CSR receiver with a bcdDevice value of 0x8891,
> a lmp_subver of 0x0x1012, a hci_rev of 0x0810 and a hci_ver of
> BLUETOOTH_VER_4_0.
I just realized that I should have opened this one and add the
chipmarkings to the commit msg here too. So I've just opened it
and took a look.
This one has a Barrot 8041a02 chip and searching for 8041a92 shows that
the internet is full of reports of how crappy it is.
I guess this patch probably will get some review remarks anyways,
but let me know if you want a v3 with just the chip added to the
commit msg.
Regards,
Hans
>
> Summarizing this specific fake CSR receiver has the following 2 issues:
>
> 1. The bulk rx endpoint will never report any data unless
> the device was suspended at least once.
>
> 2. They will not wakeup when autosuspended and receiving data on their
> bulk rx endpoint from e.g. a keyboard or mouse (IOW remote-wakeup support
> is broken for the bulk endpoint).
>
> Add a workaround for 1. which enables runtime-suspend, force-suspends
> the hci and then wakes-it up by disabling runtime-suspend again.
>
> Add a workaround for 2. which clears the hci's can_wake flag, this way
> the hci will still be autosuspended when it is not open.
>
> Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
> ---
> drivers/bluetooth/btusb.c | 32 ++++++++++++++++++++++++++++++++
> 1 file changed, 32 insertions(+)
>
> diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c
> index ac7fede4f951..48e404dfa246 100644
> --- a/drivers/bluetooth/btusb.c
> +++ b/drivers/bluetooth/btusb.c
> @@ -1768,6 +1768,7 @@ static int btusb_setup_csr(struct hci_dev *hdev)
> struct hci_rp_read_local_version *rp;
> struct sk_buff *skb;
> bool is_fake = false;
> + int ret;
>
> BT_DBG("%s", hdev->name);
>
> @@ -1856,6 +1857,37 @@ static int btusb_setup_csr(struct hci_dev *hdev)
> */
> clear_bit(HCI_QUIRK_RESET_ON_CLOSE, &hdev->quirks);
> clear_bit(HCI_QUIRK_SIMULTANEOUS_DISCOVERY, &hdev->quirks);
> +
> + /*
> + * Some of these clones are really messed-up:
> + * 1. Their bulk rx endpoint will never report any data unless
> + * the device was suspended at least once (yes really).
> + * 2. They will not wakeup when autosuspended and receiving data
> + * on their bulk rx endpoint from e.g. a keyboard or mouse
> + * (IOW remote-wakeup support is broken for the bulk endpoint).
> + *
> + * To fix 1. enable runtime-suspend, force-suspend the
> + * hci and then wake-it up by disabling runtime-suspend.
> + *
> + * To fix 2. clear the hci's can_wake flag, this way the hci
> + * will still be autosuspended when it is not open.
> + */
> + if (device_can_wakeup(&data->udev->dev)) {
> + pm_runtime_allow(&data->udev->dev);
> +
> + ret = pm_runtime_suspend(&data->udev->dev);
> + if (ret >= 0)
> + msleep(200);
> + else
> + bt_dev_warn(hdev, "Failed to suspend the device for CSR clone receive-issue workaround\n");
> +
> + pm_runtime_forbid(&data->udev->dev);
> +
> + device_set_wakeup_capable(&data->udev->dev, false);
> + /* Re-enable autosuspend if this was requested */
> + if (enable_autosuspend)
> + usb_enable_autosuspend(data->udev);
> + }
> }
>
> kfree_skb(skb);
>
