linux-kernel - Re: [PATCH v1] Bluetooth: hci_qca: Drop unused event during BT on

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Message-ID: <2be3922d-8899-4e58-aa23-57a0b5cfc111@molgen.mpg.de>
Date: Wed, 21 Aug 2024 06:49:05 +0200
From: Paul Menzel <pmenzel@...gen.mpg.de>
To: Cheng Jiang <quic_chejiang@...cinc.com>
Cc: Marcel Holtmann <marcel@...tmann.org>,
 Luiz Augusto von Dentz <luiz.dentz@...il.com>,
 linux-bluetooth@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1] Bluetooth: hci_qca: Drop unused event during BT on

Dear Cheng,


Thank you for your patch.

Am 21.08.24 um 06:16 schrieb Cheng Jiang:

> Is there any comment for the changes? Thanks!
> 
> On 7/26/2024 5:58 PM, Cheng Jiang wrote:
>> For the WCN6750/WCN6855/WCN7850, the vendor command for a baudrate
>> change is not sent as synchronous HCI command, controller sends the
>> corresponding vendor event with the new baudrate. It needs to be
>> dropped, otherwise it may be misinterpreted as response to a later
>> command.

Is that documented in some datasheet?

How can this behavior be tested, and your change be verified? How did 
you test it?

>> Signed-off-by: Cheng Jiang <quic_chejiang@...cinc.com>
>> ---
>>   drivers/bluetooth/hci_qca.c | 16 +++++++++++++++-
>>   1 file changed, 15 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c
>> index ca6466676902..f497d601e035 100644
>> --- a/drivers/bluetooth/hci_qca.c
>> +++ b/drivers/bluetooth/hci_qca.c
>> @@ -1206,7 +1206,15 @@ static int qca_recv_event(struct hci_dev *hdev, struct sk_buff *skb)
>>   		 * vendor command).
>>   		 */
>>   
>> -		if (hdr->evt == HCI_EV_VENDOR)
>> +		/* For the WCN6750/WCN6855/WCN7850, like the WCN3990, the

Does “like the” mean “and” in this situation? WCN3990 is not mentioned 
in the commit message.

>> +		 * vendor command for a baudrate change command isn't sent as
>> +		 * synchronous HCI command, the controller sends the corresponding
>> +		 * command complete event with the new baudrate. The event is
>> +		 * received and properly decoded after changing the baudrate of
>> +		 * the host port. It needs to be dropped.
>> +		 */
>> +

It’d remove the blank line.

>> +		if (hdr->evt == HCI_EV_VENDOR || hdr->evt == HCI_EV_CMD_COMPLETE)
>>   			complete(&qca->drop_ev_comp);

Excuse my ignorance. Is `HCI_EV_CMD_COMPLETE` only sent in case of a 
baudrate change?

>>   		kfree_skb(skb);
>> @@ -1497,6 +1505,9 @@ static int qca_set_speed(struct hci_uart *hu, enum qca_speed_type speed_type)
>>   
>>   		switch (soc_type) {
>>   		case QCA_WCN3990:
>> +		case QCA_WCN6750:
>> +		case QCA_WCN6855:
>> +		case QCA_WCN7850:

So setting the speed wasn’t working before?

>>   			reinit_completion(&qca->drop_ev_comp);
>>   			set_bit(QCA_DROP_VENDOR_EVENT, &qca->flags);
>>   			break;
>> @@ -1531,6 +1542,9 @@ static int qca_set_speed(struct hci_uart *hu, enum qca_speed_type speed_type)
>>   
>>   		switch (soc_type) {
>>   		case QCA_WCN3990:
>> +		case QCA_WCN6750:
>> +		case QCA_WCN6855:
>> +		case QCA_WCN7850:
>>   			/* Wait for the controller to send the vendor event
>>   			 * for the baudrate change command.
>>   			 */


Kind regards,

Paul