linux-kernel - Re: [RFC PATCH v5 0/5] Bluetooth: Handle system suspend gracefully

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Message-Id: <C9E912BC-01E0-4E5D-ABC9-DBA932231E50@holtmann.org>
Date:   Wed, 11 Mar 2020 16:03:12 +0100
From:   Marcel Holtmann <marcel@...tmann.org>
To:     Abhishek Pandit-Subedi <abhishekpandit@...omium.org>
Cc:     Luiz Augusto von Dentz <luiz.dentz@...il.com>,
        Alain Michaud <alainm@...omium.org>,
        linux-bluetooth@...r.kernel.org,
        chromeos-bluetooth-upstreaming@...omium.org,
        "David S. Miller" <davem@...emloft.net>,
        Johan Hedberg <johan.hedberg@...il.com>,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        Jakub Kicinski <kuba@...nel.org>
Subject: Re: [RFC PATCH v5 0/5] Bluetooth: Handle system suspend gracefully

Hi Abhishek,

> This patch series prepares the Bluetooth controller for system suspend
> by disconnecting all devices and preparing the event filter and LE
> whitelist with devices that can wake the system from suspend.
> 
> The main motivation for doing this is so we can enable Bluetooth as
> a wake up source during suspend without it being noisy. Bluetooth should
> wake the system when a HID device receives user input but otherwise not
> send any events to the host.
> 
> This patch series was tested on several Chromebooks with both btusb and
> hci_serdev on kernel 4.19. The set of tests was basically the following:
> * Reconnects after suspend succeed
> * HID devices can wake the system from suspend (needs some related bluez
>  changes to call the Set Wake Capable management command)
> * System properly pauses and unpauses discovery + advertising around
>  suspend
> * System does not wake from any events from non wakeable devices
> 
> Series 2 has refactored the change into multiple smaller commits as
> requested. I tried to simplify some of the whitelist filtering edge
> cases but unfortunately it remains quite complex.
> 
> Series 3 has refactored it further and should have resolved the
> whitelisting complexity in series 2.
> 
> Series 4 adds a fix to check for powered down and powering down adapters.
> 
> Series 5 moves set_wake_capable to the last patch in the series and
> changes BT_DBG to bt_dev_dbg.
> 
> Please review and provide any feedback.

so I was planning to apply patches 1-4. The only thing that I noticed was that patch 2 introduces the following warning.

  CC      net/bluetooth/hci_request.o
net/bluetooth/hci_request.c: In function ‘hci_req_prepare_suspend’:
net/bluetooth/hci_request.c:973:6: warning: unused variable ‘old_state’ [-Wunused-variable]
  973 |  int old_state;
      |      ^~~~~~~~~

I think this variable should only be introduced in patch 4. Are you able to respin this series so that the variable moves to patch 4. If not, I can try to fix this myself.

Regards

Marcel