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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: <E52C04D8-67C6-4949-B988-A61F6FCD1434@holtmann.org>
Date:   Thu, 30 Jul 2020 17:50:48 +0800
Cc:     Abhishek Pandit-Subedi <abhishekpandit@chromium.org>,
        chromeos-bluetooth-upstreaming 
        <chromeos-bluetooth-upstreaming@chromium.org>,
        Bluetooth Kernel Mailing List 
        <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: <8FE329BB-706A-4D16-950C-A7571FE0B40A@canonical.com>
References: <20200729161740.1.Ib03d0827c8e48fc3df887fec698f79fa335c9274@changeid>
 <8DFB5D1A-AA7E-4960-9937-4FD00827937B@canonical.com>
 <E52C04D8-67C6-4949-B988-A61F6FCD1434@holtmann.org>
To:     Marcel Holtmann <marcel@holtmann.org>
Sender: linux-bluetooth-owner@vger.kernel.org
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> On Jul 30, 2020, at 15:30, Marcel Holtmann <marcel@holtmann.org> wrote:
> 
> Hi Kai-Heng,
> 
>>> 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.
> 
> lets do that and lets do it quickly since the merge window is close. Otherwise I really have to revert that patch.

Ok, I no longer observe the original issue with the patch reverted.
Acked-by: Kai-Heng Feng <kai.heng.feng@canonical.com>

> 
> Regards
> 
> Marcel
>