linux-kernel - Re: [PATCH] Bluetooth: Check scan state before disabling during suspend

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Date:   Tue, 2 Jun 2020 08:26:59 -0400
From:   Alain Michaud <alainmichaud@...gle.com>
To:     Abhishek Pandit-Subedi <abhishekpandit@...omium.org>
Cc:     Manish Mandlik <mmandlik@...gle.com>,
        Marcel Holtmann <marcel@...tmann.org>,
        Luiz Augusto von Dentz <luiz.dentz@...il.com>,
        Bluez mailing list <linux-bluetooth@...r.kernel.org>,
        ChromeOS Bluetooth Upstreaming 
        <chromeos-bluetooth-upstreaming@...omium.org>,
        "David S. Miller" <davem@...emloft.net>,
        Johan Hedberg <johan.hedberg@...il.com>,
        netdev <netdev@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Jakub Kicinski <kuba@...nel.org>
Subject: Re: [PATCH] Bluetooth: Check scan state before disabling during suspend

On Mon, Jun 1, 2020 at 9:49 PM Abhishek Pandit-Subedi
<abhishekpandit@...omium.org> wrote:
>
> Hey linux-bluetooth,
>
> We found this bug when reverting some Chromium maintained patches in
> our repository that was conditionally dropping LE scan enable commands
> if it wasn't toggling between true/false. On some Intel controllers,
> disabling LE scan when it's already disabled resulted in a "Command
> Disallowed" and this was causing suspend to fail.
>
> On Mon, Jun 1, 2020 at 6:43 PM Manish Mandlik <mmandlik@...gle.com> wrote:
> >
> > Check current scan state by checking HCI_LE_SCAN flag and send scan
> > disable command only if scan is already enabled.
> >
> > Signed-off-by: Manish Mandlik <mmandlik@...gle.com>
> > ---
> >
> >  net/bluetooth/hci_request.c | 10 ++++++----
> >  1 file changed, 6 insertions(+), 4 deletions(-)
> >
> > diff --git a/net/bluetooth/hci_request.c b/net/bluetooth/hci_request.c
> > index 1fc55685da62d..1acf5b8e0910c 100644
> > --- a/net/bluetooth/hci_request.c
> > +++ b/net/bluetooth/hci_request.c
> > @@ -998,8 +998,9 @@ static void hci_req_set_event_filter(struct hci_request *req)
> >
> >  static void hci_req_config_le_suspend_scan(struct hci_request *req)
> >  {
> > -       /* Can't change params without disabling first */
> > -       hci_req_add_le_scan_disable(req);
> > +       /* Before changing params disable scan if enabled */
> > +       if (hci_dev_test_flag(req->hdev, HCI_LE_SCAN))
> > +               hci_req_add_le_scan_disable(req);
> >
> >         /* Configure params and enable scanning */
> >         hci_req_add_le_passive_scan(req);
> > @@ -1065,8 +1066,9 @@ void hci_req_prepare_suspend(struct hci_dev *hdev, enum suspended_state next)
> >                 page_scan = SCAN_DISABLED;
> >                 hci_req_add(&req, HCI_OP_WRITE_SCAN_ENABLE, 1, &page_scan);
> >
> > -               /* Disable LE passive scan */
> > -               hci_req_add_le_scan_disable(&req);
> > +               /* Disable LE passive scan if enabled */
> > +               if (hci_dev_test_flag(hdev, HCI_LE_SCAN))
> > +                       hci_req_add_le_scan_disable(&req);
> >
> >                 /* Mark task needing completion */
> >                 set_bit(SUSPEND_SCAN_DISABLE, hdev->suspend_tasks);
> > --
> > 2.27.0.rc2.251.g90737beb825-goog
> >
>
> Reviewed-by: Abhishek Pandit-Subedi <abhishekpandit@...omium.org>
Reviewed-by: Alain Michaud <alainm@...omium.org>
>
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