linux-kernel - Re: [PATCH] Revert "Bluetooth: btusb: Disable runtime suspend on Realtek devices"

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Date:   Thu, 30 Jul 2020 09:30:16 +0200
From:   Marcel Holtmann <marcel@...tmann.org>
To:     Kai-Heng Feng <kai.heng.feng@...onical.com>
Cc:     Abhishek Pandit-Subedi <abhishekpandit@...omium.org>,
        chromeos-bluetooth-upstreaming 
        <chromeos-bluetooth-upstreaming@...omium.org>,
        Bluetooth Kernel Mailing List 
        <linux-bluetooth@...r.kernel.org>,
        Alex Lu <alex_lu@...lsil.com.cn>, linux-pm@...r.kernel.org,
        Johan Hedberg <johan.hedberg@...il.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Revert "Bluetooth: btusb: Disable runtime suspend on
 Realtek devices"

Hi Kai-Heng,

>> On Jul 30, 2020, at 07:17, Abhishek Pandit-Subedi <abhishekpandit@...omium.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@...omium.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.

Regards

Marcel