Message-ID: <b238f666-9238-fb42-cd46-ad628e576218@redhat.com>
Date:   Sat, 17 Jul 2021 11:31:56 +0200
From:   Hans de Goede <hdegoede@...hat.com>
To:     Ismael Ferreras Morezuelas <swyterzone@...il.com>,
        Marcel Holtmann <marcel@...tmann.org>
Cc:     Johan Hedberg <johan.hedberg@...il.com>,
        Luiz Augusto von Dentz <luiz.dentz@...il.com>,
        BlueZ <linux-bluetooth@...r.kernel.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Bluetooth: btusb: Make the CSR clone chip force-suspend
 workaround more generic

Hi,

On 7/17/21 1:21 AM, Ismael Ferreras Morezuelas wrote:
> Turns out Hans de Goede completed the work I started last year trying to
> improve Chinese-clone detection of CSR controller chips. Quirk after quirk
> these Bluetooth dongles are more usable now.
> 
> Even after a few BlueZ regressions; these clones are so fickle that some
> days they stop working altogether. Except on Windows, they work fine.
> 
> 
> But this force-suspend initialization quirk seems to mostly do the trick,
> after a lot of testing Bluetooth now seems to work *all* the time.
> 
> The only problem is that the solution ended up being masked under a very
> stringent check; when there are probably hundreds of fake dongle
> models out there that benefit from a good reset. Make it so.
> 
> 
> Fixes: 81cac64ba258a ("Bluetooth: Deal with USB devices that are faking CSR vendor")
> Fixes: cde1a8a992875 ("Bluetooth: btusb: Fix and detect most of the Chinese Bluetooth controllers")
> Fixes: d74e0ae7e0303 ("Bluetooth: btusb: Fix detection of some fake CSR controllers with a bcdDevice val of 0x0134")
> Fixes: 0671c0662383e ("Bluetooth: btusb: Add workaround for remote-wakeup issues with Barrot 8041a02 fake CSR controllers")
> 
> Cc: stable@...r.kernel.org
> Cc: Hans de Goede <hdegoede@...hat.com>
> Tested-by: Ismael Ferreras Morezuelas <swyterzone@...il.com>
> Signed-off-by: Ismael Ferreras Morezuelas <swyterzone@...il.com>

FWIW I'm fine with making the force-suspend once quirk which
I added generic to all clones.

The new code looks good to me:

Reviewed-by: Hans de Goede <hdegoede@...hat.com>

Regards,

Hans





> ---
> 
> I've changed the warning line to make it easy to grep and detect if this updated
> workaround is part of the driver. Should make it much more obvious to users in
> case their dongle doesn't work for other reasons. There's a clear then-now.
> 
> Easy to narrow other future issues down. Let me know what you think.
> 
>  drivers/bluetooth/btusb.c | 61 +++++++++++++++++++++------------------
>  1 file changed, 33 insertions(+), 28 deletions(-)
> 
> diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c
> index a9855a2dd..197cafe75 100644
> --- a/drivers/bluetooth/btusb.c
> +++ b/drivers/bluetooth/btusb.c
> @@ -1890,7 +1890,7 @@ static int btusb_setup_csr(struct hci_dev *hdev)
>  		is_fake = true;
>  
>  	if (is_fake) {
> -		bt_dev_warn(hdev, "CSR: Unbranded CSR clone detected; adding workarounds...");
> +		bt_dev_warn(hdev, "CSR: Unbranded CSR clone detected; adding workarounds and force-suspending once...");
>  
>  		/* Generally these clones have big discrepancies between
>  		 * advertised features and what's actually supported.
> @@ -1907,41 +1907,46 @@ static int btusb_setup_csr(struct hci_dev *hdev)
>  		clear_bit(HCI_QUIRK_SIMULTANEOUS_DISCOVERY, &hdev->quirks);
>  
>  		/*
> -		 * Special workaround for clones with a Barrot 8041a02 chip,
> -		 * 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).
> +		 * Special workaround for these BT 4.0 chip clones, and potentially more:
> +		 *
> +		 * - 0x0134: a Barrot 8041a02                 (HCI rev: 0x1012 sub: 0x0810)
> +		 * - 0x7558: IC markings FR3191AHAL 749H15143 (HCI rev/sub-version: 0x0709)
> +		 *
> +		 * These controllers 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
> +		 * 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.
> +		 * HCI and then wake-it up by disabling runtime-suspend.
>  		 *
> -		 * To fix 2. clear the hci's can_wake flag, this way the hci
> +		 * To fix 2. clear the HCI's can_wake flag, this way the HCI
>  		 * will still be autosuspended when it is not open.
> +		 *
> +		 * --
> +		 *
> +		 * Because these are widespread problems we prefer generic solutions; so
> +		 * apply this initialization quirk to every controller that gets here,
> +		 * it should be harmless. The alternative is to not work at all.
>  		 */
> -		if (bcdDevice == 0x8891 &&
> -		    le16_to_cpu(rp->lmp_subver) == 0x1012 &&
> -		    le16_to_cpu(rp->hci_rev) == 0x0810 &&
> -		    le16_to_cpu(rp->hci_ver) == BLUETOOTH_VER_4_0) {
> -			bt_dev_warn(hdev, "CSR: detected a fake CSR dongle using a Barrot 8041a02 chip, this chip is very buggy and may have issues");
> -
> -			pm_runtime_allow(&data->udev->dev);
> +		pm_runtime_allow(&data->udev->dev);
>  
> -			ret = pm_runtime_suspend(&data->udev->dev);
> -			if (ret >= 0)
> -				msleep(200);
> -			else
> -				bt_dev_err(hdev, "Failed to suspend the device for Barrot 8041a02 receive-issue workaround");
> -
> -			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);
> -		}
> +		ret = pm_runtime_suspend(&data->udev->dev);
> +		if (ret >= 0)
> +			msleep(200);
> +		else
> +			bt_dev_err(hdev, "CSR: Failed to suspend the device for our Barrot 8041a02 receive-issue workaround");
> +
> +		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);
> 

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