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Subject: Re: [PATCH v1 6/7] Bluetooth: hci_mediatek: Add protocol support for
 MediaTek serial devices
From:   Marcel Holtmann <marcel@holtmann.org>
In-Reply-To: <1525762084.14468.20.camel@mtkswgap22>
Date:   Tue, 8 May 2018 09:27:48 +0200
Cc:     Rob Herring <robh+dt@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Johan Hedberg <johan.hedberg@gmail.com>,
        devicetree <devicetree@vger.kernel.org>,
        BlueZ development <linux-bluetooth@vger.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
        linux-mediatek@lists.infradead.org, linux-kernel@vger.kernel.org
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Message-Id: <D474053D-6910-4B04-8B98-59B96FEB86BC@holtmann.org>
References: <cover.1522736996.git.sean.wang@mediatek.com>
 <f0e0a0b7f1dc3845dc6eafb4ccd60284d1675f8d.1522736996.git.sean.wang@mediatek.com>
 <A7391E5D-2945-415B-8AB1-8DFBF2E65878@holtmann.org>
 <1525762084.14468.20.camel@mtkswgap22>
To:     Sean Wang <sean.wang@mediatek.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Hi Sean,

>>> +
>>> +static int mtk_wmt_cmd_sync(struct hci_uart *hu, u8 opcode, u8 flag, u16 plen,
>>> +			    const void *param)
>>> +{
>>> +	struct mtk_bt_dev *btdev = hu->priv;
>>> +	struct hci_command_hdr *hhdr;
>>> +	struct hci_acl_hdr *ahdr;
>>> +	struct mtk_wmt_hdr *whdr;
>>> +	struct sk_buff *skb;
>>> +	int ret = 0;
>>> +
>>> +	init_completion(&btdev->wmt_cmd);
>>> +
>>> +	skb = bt_skb_alloc(plen + MTK_WMT_CMD_SIZE, GFP_KERNEL);
>>> +	if (!skb)
>>> +		return -ENOMEM;
>>> +
>>> +	/*
>>> +	 * WMT data is carried in either ACL or HCI format with op code as
>>> +	 * 0xfc6f and followed by a WMT header and its actual payload.
>>> +	 */
>> 
>> Please use net subsystem comment style.
>> 
>>> +	switch (opcode) {
>>> +	case MTK_WMT_PATCH_DWNLD:
>>> +		ahdr = skb_put(skb, HCI_ACL_HDR_SIZE);
>>> +		ahdr->handle = cpu_to_le16(0xfc6f);
>>> +		ahdr->dlen   = cpu_to_le16(plen + MTK_WMT_HDR_SIZE);
>>> +		break;
>>> +	default:
>>> +		hhdr = skb_put(skb, HCI_COMMAND_HDR_SIZE);
>>> +		hhdr->opcode = cpu_to_le16(0xfc6f);
>>> +		hhdr->plen = plen + MTK_WMT_HDR_SIZE;
>>> +		break;
>>> +	}
>>> +
>>> +	hci_skb_pkt_type(skb) = opcode == MTK_WMT_PATCH_DWNLD ?
>>> +				HCI_ACLDATA_PKT : HCI_COMMAND_PKT;
>> 
>> Why not move that into the switch statement above.
>> 
>>> +
>>> +	/* Start to build a WMT header and its actual payload. */
>>> +	whdr = skb_put(skb, MTK_WMT_HDR_SIZE);
>>> +	whdr->dir = 1;
>>> +	whdr->op = opcode;
>>> +	whdr->dlen = cpu_to_le16(plen + 1);
>>> +	whdr->flag = flag;
>>> +	skb_put_data(skb, param, plen);
>>> +
>>> +	mtk_enqueue(hu, skb);
>>> +	hci_uart_tx_wakeup(hu);
>>> +
>>> +	/*
>>> +	 * Waiting a WMT event response, while we must take care in case of
>>> +	 * failures for the wait.
>>> +	 */
>>> +	ret = wait_for_completion_interruptible_timeout(&btdev->wmt_cmd, HZ);
>>> +
>>> +	return ret > 0 ? 0 : ret < 0 ? ret : -ETIMEDOUT;
>>> +}
>> 
>> All in all I am not convinced that this is super clean. I get that we need something special for having this in the ACL data packets, but for the standard HCI command I prefer that __hci_cmd_sync is used. I addition, it seems that patch download is the only special case and that happens before at the setup stage. So we could make things special for that. I need to understand this a bit better. Can I get a btmon -w trace.log file from the whole init procedure.
>> 
> 
> While i was trying to rewrite the driver based on btuart.c. you posted
> on RFC, I used __hci_cmd_sync_ev to replace such kinds of SoC specific
> hci command sending which I've done previously with mtk_wmt_cmd_sync.
> 
> However, eventually, I got a cmd_timer timeout whose message printed
> on console as "Bluetooth: hci0: command 0xfc6f tx timeout".
> 
> The mtk soc specific cmd/event I posted below, I dumped directly in
> driver, always uses cmd as opcode 0xfc6f, and its event id as 0xe4.
> 
> It appears to the event id is not standard and thus it cannot cancel the
> cmd timer when the special hci event is being handled. This way can we
> can still use __hci_cmd_sync api ?
> 
> [    4.896200] hci tx: 00000000: 01 6f fc 05 01 07 01 00 04    
> [    4.904671] hci rx: 00000000: e4 05 02 07 01 00
> 00                             
> [    4.912859] Bluetooth: hci0 event 0xe4
> 
> 
> buildroot login: [    6.914509] Bluetooth: hci0: command 0xfc6f tx
> timeout
> [    6.919831] hci tx: 00000000: 01 6f fc 06 01 06 02 00 00
> 01                    .o........
> [    7.006631] hci rx: 00000000: e4 05 02 06 01 00
> 00                             .......
> [    7.014821] Bluetooth: hci0 event 0xe4

can you just start btmon before loading the module / driver? It makes it a lot easier since it will actually decode the basics for us. If there is a bug within __hci_cmd_sync_ev, then we are going to fix it.

So all the MTK vendor commands respond with a vendor event? Or are there some that do the standard command status/complete handling?

Regards

Marcel