linux-kernel - Re: [PATCH v7 4/4] Bluetooth: btqca: inject command complete event during fw download

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Message-Id: <1FC4CC11-B070-4ACF-9107-857A4D392876@holtmann.org>
Date:   Sun, 30 Dec 2018 09:10:45 +0100
From:   Marcel Holtmann <marcel@...tmann.org>
To:     Balakrishna Godavarthi <bgodavar@...eaurora.org>
Cc:     Johan Hedberg <johan.hedberg@...il.com>, mka@...omium.org,
        linux-kernel@...r.kernel.org, linux-bluetooth@...r.kernel.org,
        hemantg@...eaurora.org, linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH v7 4/4] Bluetooth: btqca: inject command complete event
 during fw download

Hi Balakrishna,

>>> Latest qualcomm chips are not sending an command complete event for
>>> every firmware packet sent to chip. They only respond with a vendor
>>> specific event for the last firmware packet. This optimization will
>>> decrease the BT ON time. Due to this we are seeing a timeout error
>>> message logs on the console during firmware download. Now we are
>>> injecting a command complete event once we receive an vendor specific
>>> event for the last RAM firmware packet.
>>> Signed-off-by: Balakrishna Godavarthi <bgodavar@...eaurora.org>
>>> ---
>>> drivers/bluetooth/btqca.c | 39 ++++++++++++++++++++++++++++++++++++++-
>>> drivers/bluetooth/btqca.h |  3 +++
>>> 2 files changed, 41 insertions(+), 1 deletion(-)
>>> diff --git a/drivers/bluetooth/btqca.c b/drivers/bluetooth/btqca.c
>>> index ec9e03a6b778..0b533f65f652 100644
>>> --- a/drivers/bluetooth/btqca.c
>>> +++ b/drivers/bluetooth/btqca.c
>>> @@ -144,6 +144,7 @@ static void qca_tlv_check_data(struct rome_config *config,
>>> 		 * In case VSE is skipped, only the last segment is acked.
>>> 		 */
>>> 		config->dnld_mode = tlv_patch->download_mode;
>>> +		config->dnld_type = config->dnld_mode;
>>> 		BT_DBG("Total Length           : %d bytes",
>>> 		       le32_to_cpu(tlv_patch->total_size));
>>> @@ -264,6 +265,31 @@ static int qca_tlv_send_segment(struct hci_dev *hdev, int seg_size,
>>> 	return err;
>>> }
>>> +static int qca_inject_cmd_complete_event(struct hci_dev *hdev)
>>> +{
>>> +	struct hci_event_hdr *hdr;
>>> +	struct hci_ev_cmd_complete *evt;
>>> +	struct sk_buff *skb;
>>> +
>>> +	skb = bt_skb_alloc(sizeof(*hdr) + sizeof(*evt) + 1, GFP_KERNEL);
>>> +	if (!skb)
>>> +		return -ENOMEM;
>>> +
>>> +	hdr = skb_put(skb, sizeof(*hdr));
>>> +	hdr->evt = HCI_EV_CMD_COMPLETE;
>>> +	hdr->plen = sizeof(*evt) + 1;
>>> +
>>> +	evt = skb_put(skb, sizeof(*evt));
>>> +	evt->ncmd = 1;
>>> +	evt->opcode = HCI_OP_NOP;
>>> +
>>> +	skb_put_u8(skb, QCA_HCI_CC_SUCCESS);
>>> +
>>> +	hci_skb_pkt_type(skb) = HCI_EVENT_PKT;
>>> +
>>> +	return hci_recv_frame(hdev, skb);
>>> +}
>>> +
>>> static int qca_download_firmware(struct hci_dev *hdev,
>>> 				  struct rome_config *config)
>>> {
>>> @@ -297,11 +323,22 @@ static int qca_download_firmware(struct hci_dev *hdev,
>>> 		ret = qca_tlv_send_segment(hdev, segsize, segment,
>>> 					    config->dnld_mode);
>>> 		if (ret)
>>> -			break;
>>> +			goto out;
>>> 		segment += segsize;
>>> 	}
>>> +	/* Latest qualcomm chipsets are not sending a command complete event
>>> +	 * for every fw packet sent. They only respond with a vendor specific
>>> +	 * event for the last packet. This optimization in the chip will
>>> +	 * decrease the BT in initialization time. Here we will inject a command
>>> +	 * complete event to avoid a command timeout error message.
>>> +	 */
>>> +	if ((config->dnld_type == ROME_SKIP_EVT_VSE_CC ||
>>> +	    config->dnld_type == ROME_SKIP_EVT_VSE))
>>> +		return qca_inject_cmd_complete_event(hdev);
>>> +
>> have you actually considered using __hci_cmd_send in that case. It is
>> allowed for vendor OGF to use that command. I see you actually do use
>> it and now I am failing to understand what this is for.
> [Bala]: thanks for reviewing the change.
> 
> __hci_cmd_send() can be used only to send the command to the chip. it will not wait for the response for the command sent.
> 
> as you know that every vendor command sent to chip will respond with vendor specific event and command complete event.
> but in our case chip will only respond with vendor specific event only. so we are injecting command complete event.

and __hci_cmd_sync_ev is also not working for you? However since you are not waiting for the vendor event anyway and just injecting cmd_complete, I wonder what’s the difference in just using __hci_cmd_send and not bothering to wait or inject at all. I am failing to see where this injection makes a difference.

For me it is a big difference if we are injecting one event like in the case of Intel compared to injecting one for every command. It will show a wrong picture in btmon and that is a bad idea.

Regards

Marcel