Re: [PATCH v1 6/7] Bluetooth: hci_mediatek: Add protocol support for MediaTek serial devices

From: Marcel Holtmann
Date: Tue May 08 2018 - 03:27:57 EST


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