netdev - Re: [PATCH v2 1/3] Bluetooth: Add new quirk for broken local ext features max

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Message-ID: <CA+E=qVd6sRCnKZz2gizxqP=DVQPttW4JgmhE7SHYJhbnQADpwA@mail.gmail.com>
Date:   Sat, 5 Nov 2022 00:13:30 -0700
From:   Vasily Khoruzhick <anarsoul@...il.com>
To:     Marcel Holtmann <marcel@...tmann.org>
Cc:     Bastian Germann <bage@...ian.org>,
        Rob Herring <robh+dt@...nel.org>,
        Maxime Ripard <mripard@...nel.org>,
        Chen-Yu Tsai <wens@...e.org>,
        Johan Hedberg <johan.hedberg@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kubakici@...pl>, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-bluetooth@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [PATCH v2 1/3] Bluetooth: Add new quirk for broken local ext
 features max_page

On Thu, Jun 2, 2022 at 9:10 AM Marcel Holtmann <marcel@...tmann.org> wrote:
>
> Hi Bastian,

Hi Marcel,

> > Some adapters (e.g. RTL8723CS) advertise that they have more than
> > 2 pages for local ext features, but they don't support any features
> > declared in these pages. RTL8723CS reports max_page = 2 and declares
> > support for sync train and secure connection, but it responds with
> > either garbage or with error in status on corresponding commands.
>
>
> please include btmon output for the garbage and/or error.

We had it in v1 thread, here is relevant part:

< HCI Command: Read Local Extend.. (0x04|0x0004) plen 1  #228 [hci0] 6.889869
        Page: 2
> HCI Event: Command Complete (0x0e) plen 14             #229 [hci0] 6.890487
      Read Local Extended Features (0x04|0x0004) ncmd 2
        Status: Success (0x00)
        Page: 2/2
        Features: 0x5f 0x03 0x00 0x00 0x00 0x00 0x00 0x00
          Connectionless Slave Broadcast - Master
          Connectionless Slave Broadcast - Slave
          Synchronization Train
          Synchronization Scan
          Inquiry Response Notification Event
          Coarse Clock Adjustment
          Secure Connections (Controller Support)
          Ping
< HCI Command: Delete Stored Lin.. (0x03|0x0012) plen 7  #230 [hci0] 6.890559
        Address: 00:00:00:00:00:00 (OUI 00-00-00)
        Delete all: 0x01
> HCI Event: Command Complete (0x0e) plen 6              #231 [hci0] 6.891170
      Delete Stored Link Key (0x03|0x0012) ncmd 2
        Status: Success (0x00)
        Num keys: 0
< HCI Command: Read Synchronizat.. (0x03|0x0077) plen 0  #232 [hci0] 6.891199
> HCI Event: Command Complete (0x0e) plen 9              #233 [hci0] 6.891788
      Read Synchronization Train Parameters (0x03|0x0077) ncmd 2
        invalid packet size
        01 ac bd 11 80 80                                ......
= Close Index: 00:E0:4C:23:99:87                              [hci0] 6.891832

> >
> > Signed-off-by: Vasily Khoruzhick <anarsoul@...il.com>
> > [rebase on current tree]
> > Signed-off-by: Bastian Germann <bage@...ian.org>
> > ---
> > include/net/bluetooth/hci.h | 7 +++++++
> > net/bluetooth/hci_event.c   | 4 +++-
> > 2 files changed, 10 insertions(+), 1 deletion(-)
> >
> > diff --git a/include/net/bluetooth/hci.h b/include/net/bluetooth/hci.h
> > index 69ef31cea582..af26e8051905 100644
> > --- a/include/net/bluetooth/hci.h
> > +++ b/include/net/bluetooth/hci.h
> > @@ -265,6 +265,13 @@ enum {
> >        * runtime suspend, because event filtering takes place there.
> >        */
> >       HCI_QUIRK_BROKEN_FILTER_CLEAR_ALL,
> > +
> > +     /* When this quirk is set, max_page for local extended features
> > +      * is set to 1, even if controller reports higher number. Some
> > +      * controllers (e.g. RTL8723CS) report more pages, but they
> > +      * don't actually support features declared there.
> > +      */
> > +     HCI_QUIRK_BROKEN_LOCAL_EXT_FTR_MAX_PAGE,
> > };
>
> Can we just call it _BROKEN_LOCAL_EXT_FEATURES_PAGE_2.
>
> Now with that said, is Secure Connections really broken? We need that bit to indicate support for this.

I don't really see the point in testing any 4.1 features if the chip
vendor claims that they are broken.

I understand your intention to get the max out of the hardware, but it
doesn't look like a good idea to me to use something that the vendor
claims to be broken.

Regards,
Vasily

> Regards
>
> Marcel
>