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Subject: Re: [PATCH] Revert "Bluetooth: btusb: Disable runtime suspend on
 Realtek devices"
From:   Kai-Heng Feng <kai.heng.feng@canonical.com>
In-Reply-To: <20200729161740.1.Ib03d0827c8e48fc3df887fec698f79fa335c9274@changeid>
Date:   Thu, 30 Jul 2020 12:14:42 +0800
Cc:     marcel@holtmann.org, chromeos-bluetooth-upstreaming@chromium.org,
        linux-bluetooth@vger.kernel.org, Alex Lu <alex_lu@realsil.com.cn>,
        linux-pm@vger.kernel.org, Johan Hedberg <johan.hedberg@gmail.com>,
        linux-kernel@vger.kernel.org
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Message-Id: <8DFB5D1A-AA7E-4960-9937-4FD00827937B@canonical.com>
References: <20200729161740.1.Ib03d0827c8e48fc3df887fec698f79fa335c9274@changeid>
To:     Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
Sender: linux-bluetooth-owner@vger.kernel.org
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Hi Abhishek,

> On Jul 30, 2020, at 07:17, Abhishek Pandit-Subedi <abhishekpandit@chromium.org> wrote:
> 
> This reverts commit 7ecacafc240638148567742cca41aa7144b4fe1e.
> 
> Testing this change on a board with RTL8822CE, I found that enabling
> autosuspend has no effect on the stability of the system. The board
> continued working after autosuspend, suspend and reboot.

The original issue was found on 8723DE. Do you have one to test with?
The rtw88 codebase has changed a lot and maybe it's already fixed in mainline.
Let me do some test and I'll report back.

> 
> The original commit makes it impossible to enable autosuspend on working
> systems so it should be reverted. Disabling autosuspend should be done
> via module param or udev in userspace instead.
> 
> Signed-off-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
> ---
> We have a few Chromebooks using the RTL 8822CE part over USB and they
> are running without problems with autosuspend enabled. While bringing up
> a new board, I found some power regressions that I was able to narrow
> down to this change so I'm requesting a revert.
> 
> I tested this on Hp Chromebook 14a (running 4.14 kernel and 5.4 kernel)
> with this revert:
> * Enabled autosuspend, used it normally with a HID device
> * Suspended the Chromebook and verified it worked normally on resume
> * Rebooted the Chromebook and verified Bluetooth was working on next
>  boot
> 
> I didn't see the issue that was originally reported with this fix. For
> the original reporter, if you're still seeing this issue, there are
> other ways to disable autosuspend for your device:
> * set module param: enable_autosuspend=0
> * change your kconfig so BT_HCIBTUSB_AUTOSUSPEND=n
> * use a udev rule to disable autosuspend for specific vid:pid
> 
> Keeping this change in the kernel makes it impossible to enable
> autosuspend so it should be reverted.

It's apparently a driver/firmware/hardware issue, so the fix should keep inside the kernel.
However, the fix can be more precise and target only 8723DE.

Kai-Heng

> 
> drivers/bluetooth/btusb.c | 4 ----
> 1 file changed, 4 deletions(-)
> 
> diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c
> index 1f51494f581812..8d2608ddfd0875 100644
> --- a/drivers/bluetooth/btusb.c
> +++ b/drivers/bluetooth/btusb.c
> @@ -4086,10 +4086,6 @@ static int btusb_probe(struct usb_interface *intf,
> 			set_bit(BTUSB_USE_ALT1_FOR_WBS, &data->flags);
> 		else
> 			bt_dev_err(hdev, "Device does not support ALT setting 1");
> -
> -		err = usb_autopm_get_interface(intf);
> -		if (err < 0)
> -			goto out_free_dev;
> 	}
> 
> 	if (!reset)
> -- 
> 2.28.0.rc0.142.g3c755180ce-goog
>