Return-Path: Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 11.5 \(3445.9.1\)) Subject: Re: [PATCH v7 2/3] Bluetooth: mediatek: Add protocol support for MediaTek serial devices From: Marcel Holtmann In-Reply-To: <1533205495.3472.144.camel@mtkswgap22> Date: Fri, 3 Aug 2018 14:51:03 +0200 Cc: Rob Herring , Mark Rutland , Johan Hedberg , devicetree , "open list:BLUETOOTH DRIVERS" , linux-arm-kernel , linux-mediatek@lists.infradead.org, linux-kernel@vger.kernel.org Message-Id: References: <1707FFA1-A294-4A95-A3BF-0910CE455232@holtmann.org> <1533192799.3472.122.camel@mtkswgap22> <1533199720.3472.136.camel@mtkswgap22> <9526E5D9-50BA-4D57-80F5-083DB7D28AFE@holtmann.org> <1533205495.3472.144.camel@mtkswgap22> To: Sean Wang Sender: linux-kernel-owner@vger.kernel.org List-ID: 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); >> >> actually the command also needs to better go via the raw_q anyway since it doesn’t come back with the cmd status or cmd complete. You have it waiting for a vendor event. Maybe with is something we need to consider with __hci_cmd_sync_ev anyway. >> >> Johan would know best since he wrote that code. Anyway, we should fix that in the core and not have you hack around it. >> > > yes, my case is that received event is neither cmd status nor cmd complete. It is completely a vendor event. > > if it wants to be solved by the core layer, do you permit that I remove the hack and then send it in the next version? we need to have a __hci_raw_sync_ev that uses the hdev->raw_q and waits for the specified event to come back. I never realized that you are missing the cmd status or cmd complete. So this is similar to the original CSR vendor commands which had the same behavior. I have the feeling that you hdev->cmd_cnt increment is just hiding the problem here. If you really think that it is not chains any side effects we can merge the driver with a big warning and fix this up. However the clean way would be for you to create a patch that introduces __hci_raw_sync_ev as describe above. Regards Marcel