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

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Date:   Thu, 30 Jul 2020 11:55:51 +0200
From:   Marcel Holtmann <marcel@...tmann.org>
To:     Abhishek Pandit-Subedi <abhishekpandit@...omium.org>
Cc:     chromeos-bluetooth-upstreaming 
        <chromeos-bluetooth-upstreaming@...omium.org>,
        Kai-Heng Feng <kai.heng.feng@...onical.com>,
        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 Abhishek,

> 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 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.
> 
> drivers/bluetooth/btusb.c | 4 ----
> 1 file changed, 4 deletions(-)

patch has been applied to bluetooth-next tree.

Regards

Marcel