Return-Path: Message-ID: <1533199720.3472.136.camel@mtkswgap22> Subject: Re: [PATCH v7 2/3] Bluetooth: mediatek: Add protocol support for MediaTek serial devices From: Sean Wang To: Marcel Holtmann CC: Rob Herring , Mark Rutland , Johan Hedberg , devicetree , "open list:BLUETOOTH DRIVERS" , linux-arm-kernel , , Date: Thu, 2 Aug 2018 16:48:40 +0800 In-Reply-To: References: <1707FFA1-A294-4A95-A3BF-0910CE455232@holtmann.org> <1533192799.3472.122.camel@mtkswgap22> Content-Type: text/plain; charset="UTF-8" MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: On Thu, 2018-08-02 at 09:38 +0200, Marcel Holtmann wrote: > Hi Sean, > [ ... ] > >>> + > >>> +static int mtk_hci_wmt_sync(struct hci_dev *hdev, u8 op, u8 flag, u16 plen, > >>> + const void *param) > >>> +{ > >>> + struct mtk_hci_wmt_cmd wc; > >>> + struct mtk_wmt_hdr *hdr; > >>> + struct sk_buff *skb; > >>> + u32 hlen; > >>> + > >>> + hlen = sizeof(*hdr) + plen; > >>> + if (hlen > 255) > >>> + return -EINVAL; > >>> + > >>> + hdr = (struct mtk_wmt_hdr *)&wc; > >>> + hdr->dir = 1; > >>> + hdr->op = op; > >>> + hdr->dlen = cpu_to_le16(plen + 1); > >>> + hdr->flag = flag; > >>> + memcpy(wc.data, param, plen); > >>> + > >>> + atomic_inc(&hdev->cmd_cnt); > >> > >> Why are you doing this one. It will need a comment here if really needed. However I doubt that this is needed. You are only using it from hdev->setup and hdev->shutdown callbacks. > >> > > > > An increment on cmd_cnt is really needed because hci_cmd_work would check whether cmd_cnt is positive and then has a decrement on cmd_cnt before a packet is being sent out. > > > > okay will add a comment. > > but you are in ->setup callback this time. So if you need this, then all the other ->setup routines would actually fail as well. Either this is leftover from when you did things in ->probe or ->open or this is some thing we might better fix properly in the core instead of papering over it. Can you recheck if this is really needed. > I added a counter print and the counter increments as below /* atomic_inc(&hdev->cmd_cnt); */ pr_info("cmd_cnt = %d\n" , atomic_read(&hdev->cmd_cnt)); skb = __hci_cmd_sync_ev(hdev, 0xfc6f, hlen, &wc, HCI_VENDOR_PKT, HCI_INIT_TIMEOUT); and the log show up that [ 334.049156] Bluetooth: hci0: command 0xfc6f tx timeout [ 334.054840] cmd_cnt = 0 [ 336.065076] Bluetooth: hci0: command 0xfc6f tx timeout [ 336.070795] cmd_cnt = 0 [ 338.080997] Bluetooth: hci0: command 0xfc6f tx timeout [ 338.086683] cmd_cnt = 0 [ 340.096907] Bluetooth: hci0: command 0xfc6f tx timeout [ 340.102609] cmd_cnt = 0 [ 342.112824] Bluetooth: hci0: command 0xfc6f tx timeout [ 342.118520] cmd_cnt = 0 [ 344.128747] Bluetooth: hci0: command 0xfc6f tx timeout [ 344.134454] cmd_cnt = 0 [ 346.144667] Bluetooth: hci0: command 0xfc6f tx timeout [ 346.150372] cmd_cnt = 0 The packet is dropped by hci_cmd_work at [1], so I also wondered why the other vendor driver works, it seems the counter needs to be incremented before every skb is being queued to cmd_q. 4257 static void hci_cmd_work(struct work_struct *work) 4258 { 4259 struct hci_dev *hdev = container_of(work, struct hci_dev, cmd_work); 4260 struct sk_buff *skb; 4261 4262 BT_DBG("%s cmd_cnt %d cmd queued %d", hdev->name, 4263 atomic_read(&hdev->cmd_cnt), skb_queue_len(&hdev->cmd_q)); 4264 4265 /* Send queued commands */ [1] 4266 if (atomic_read(&hdev->cmd_cnt)) { /* dropped when cmd_cnt is zero */ 4267 skb = skb_dequeue(&hdev->cmd_q); 4268 if (!skb) 4269 return; 4270 4271 kfree_skb(hdev->sent_cmd); 4272 4273 hdev->sent_cmd = skb_clone(skb, GFP_KERNEL); 4274 if (hdev->sent_cmd) { 4275 atomic_dec(&hdev->cmd_cnt); /* cmd_cnt-- */ 4276 hci_send_frame(hdev, skb); > >>> + > >>> + skb = __hci_cmd_sync_ev(hdev, 0xfc6f, hlen, &wc, HCI_VENDOR_PKT, > >>> + HCI_INIT_TIMEOUT); > >>> + > >>> + if (IS_ERR(skb)) { > >>> + int err = PTR_ERR(skb); > >>> + > >>> + bt_dev_err(hdev, "Failed to send wmt cmd (%d)", err); > >>> + return err; > >>> + } > >>> + > >>> + kfree_skb(skb); > >>> + > >>> + return 0; > >>> +} > >>> + [ ... ] > >>> + shdr->dlen2 = dlen & 0xff; > >>> + shdr->cs = p[0] + p[1] + p[2]; > >> > > > > as above discussion about shr->cs , it can be filled with zero to have less computing > > If it has no value, then zero it out and add a comment for it. > okay > > > >> I would add another comment here that this added the STP trailer. And change the above to mention it adds the STP header. > >> > > > > sure > > > >> And you might want to check if there is space for the trailer as well. Otherwise skb_put tends to call BUG() if I remember correctly. I know this is super unlikely since our bt_skb_alloc is pretty large. > >> > > > > sure, I will add the handling for that. it should be better to make sure all rooms are enough for header and trailer before adding content to them > > > > [ ... ] > >> You want to add a MODULE_FIRMWARE here as well. > >> > > > > okay > > Regards > > Marcel >