linux-kernel - Re: [PATCH v4] Bluetooth: hci_qca: wcn3990: Drop baudrate change vendor event

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Message-ID: <20190620234835.GZ137143@google.com>
Date:   Thu, 20 Jun 2019 16:48:35 -0700
From:   Matthias Kaehlcke <mka@...omium.org>
To:     Marcel Holtmann <marcel@...tmann.org>,
        Johan Hedberg <johan.hedberg@...il.com>
Cc:     linux-bluetooth@...r.kernel.org, linux-kernel@...r.kernel.org,
        Balakrishna Godavarthi <bgodavar@...eaurora.org>,
        Harish Bandi <c-hbandi@...eaurora.org>,
        Rocky Liao <rjliao@...eaurora.org>
Subject: Re: [PATCH v4] Bluetooth: hci_qca: wcn3990: Drop baudrate change
 vendor event

On Tue, May 21, 2019 at 12:53:07PM -0700, Matthias Kaehlcke wrote:
> Firmware download to the WCN3990 often fails with a 'TLV response size
> mismatch' error:
> 
> [  133.064659] Bluetooth: hci0: setting up wcn3990
> [  133.489150] Bluetooth: hci0: QCA controller version 0x02140201
> [  133.495245] Bluetooth: hci0: QCA Downloading qca/crbtfw21.tlv
> [  133.507214] Bluetooth: hci0: QCA TLV response size mismatch
> [  133.513265] Bluetooth: hci0: QCA Failed to download patch (-84)
> 
> This is caused by a vendor event that corresponds to an earlier command
> to change the baudrate. The event is not processed in the context of the
> baudrate change and is later interpreted as response to the firmware
> download command (which is also a vendor command), but the driver detects
> that the event doesn't have the expected amount of associated data.
> 
> More details:
> 
> For the WCN3990 the vendor command for a baudrate change isn't sent as
> synchronous HCI command, because the controller sends the corresponding
> vendor event with the new baudrate. The event is received and decoded
> after the baudrate change of the host port.
> 
> Identify the 'unused' event when it is received and don't add it to
> the queue of RX frames.
> 
> Signed-off-by: Matthias Kaehlcke <mka@...omium.org>

ping

Firmware download on WCN3990 is know to be broken for about 6
months. Can we please either apply this patch or discuss possible
alternatives? Doing nothing isn't really a great option :/ As
mentioned earlier one alternative could be a delay at the right place
with a comment why it is needed.

Thanks

Matthias