From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 596E5C43387 for ; Mon, 14 Jan 2019 10:25:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1778520873 for ; Mon, 14 Jan 2019 10:25:47 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="key not found in DNS" (0-bit key) header.d=codeaurora.org header.i=@codeaurora.org header.b="LlA9HX/7"; dkim=fail reason="key not found in DNS" (0-bit key) header.d=codeaurora.org header.i=@codeaurora.org header.b="CZBQqILl" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726584AbfANKZp (ORCPT ); Mon, 14 Jan 2019 05:25:45 -0500 Received: from smtp.codeaurora.org ([198.145.29.96]:49662 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726187AbfANKZp (ORCPT ); Mon, 14 Jan 2019 05:25:45 -0500 Received: by smtp.codeaurora.org (Postfix, from userid 1000) id C3075615CB; Mon, 14 Jan 2019 10:25:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1547461543; bh=aAMMPNo/h1q0W5/G3jJnCg9rHAdVifyaehaS7bzz7ZE=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=LlA9HX/7Epwr3h0EkbfafsBP0H2PUA8v19ddnBP5D2iOfs3SSR2/RmjCJNA/q7ziw Mm7uZGF5O45vpbNoPhPL/IC5yUoPuDbYeOTUpeDNuph6A5ob8AfKMP+YDp8uMiqi6a dKVTZfaL3KV0UgjasxYBgfXcAym6HBaOKzh3/Vfc= Received: from mail.codeaurora.org (localhost.localdomain [127.0.0.1]) by smtp.codeaurora.org (Postfix) with ESMTP id 4D47A6079C; Mon, 14 Jan 2019 10:25:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1547461541; bh=aAMMPNo/h1q0W5/G3jJnCg9rHAdVifyaehaS7bzz7ZE=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=CZBQqILl6Xz7Fl4L98fFKjVZH4OSprOwhVoyoH/2fsBekjwyAPo45/Q+9Dv2R4fDj la5evxmZsZdAPfCKsgkEktruFRGCLG+OeMjjCqyP71OcPyx5ZbQzjPbjMCpy9PS0ZT vcc1xnu0R2kmNJqVqZQXtWJurhQpq2K3XEYHHodY= MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Mon, 14 Jan 2019 15:55:41 +0530 From: Balakrishna Godavarthi To: Matthias Kaehlcke Cc: Johan Hovold , marcel@holtmann.org, johan.hedberg@gmail.com, linux-kernel@vger.kernel.org, linux-bluetooth@vger.kernel.org, hemantg@codeaurora.org, linux-arm-msm@vger.kernel.org, Johan Hovold Subject: Re: [PATCH v5 1/5] Bluetooth: hci_qca: use wait_until_sent() for power pulses In-Reply-To: <20190111233812.GJ261387@google.com> References: <20181220144639.15928-1-bgodavar@codeaurora.org> <20181220144639.15928-2-bgodavar@codeaurora.org> <20181222015947.GF261387@google.com> <20190109143822.GM14782@localhost> <2d4ee183e3c2fa964c14a5ac702043c0@codeaurora.org> <20190111005532.GC261387@google.com> <5e4b077bbcc81b624c851643bebc45f7@codeaurora.org> <20190111233812.GJ261387@google.com> Message-ID: <7c8badfceab6c4f7188156a8a9abd8ef@codeaurora.org> X-Sender: bgodavar@codeaurora.org User-Agent: Roundcube Webmail/1.2.5 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Matthias, On 2019-01-12 05:08, Matthias Kaehlcke wrote: > On Fri, Jan 11, 2019 at 08:02:00PM +0530, Balakrishna Godavarthi wrote: >> On 2019-01-11 06:25, Matthias Kaehlcke wrote: >> > On Thu, Jan 10, 2019 at 08:18:37PM +0530, Balakrishna Godavarthi wrote: >> > > Hi Johan, >> > > >> > > On 2019-01-09 20:08, Johan Hovold wrote: >> > > > On Fri, Dec 21, 2018 at 05:59:47PM -0800, Matthias Kaehlcke wrote: >> > > > > On Thu, Dec 20, 2018 at 08:16:35PM +0530, Balakrishna Godavarthi >> > > > > wrote: >> > > > > > wcn3990 requires a power pulse to turn ON/OFF along with >> > > > > > regulators. Sometimes we are observing the power pulses are sent >> > > > > > out with some time delay, due to queuing these commands. This is >> > > > > > causing synchronization issues with chip, which intern delay the >> > > > > > chip setup or may end up with communication issues. >> > > > > > >> > > > > > Signed-off-by: Balakrishna Godavarthi >> > > > > > --- >> > > > > > drivers/bluetooth/hci_qca.c | 38 ++++++++++++++----------------------- >> > > > > > 1 file changed, 14 insertions(+), 24 deletions(-) >> > > > > > >> > > > > > diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c >> > > > > > index f036c8f98ea3..5a07c2370289 100644 >> > > > > > --- a/drivers/bluetooth/hci_qca.c >> > > > > > +++ b/drivers/bluetooth/hci_qca.c >> > > > > > @@ -1013,11 +1013,9 @@ static inline void host_set_baudrate(struct hci_uart *hu, unsigned int speed) >> > > > > > hci_uart_set_baudrate(hu, speed); >> > > > > > } >> > > > > > >> > > > > > -static int qca_send_power_pulse(struct hci_dev *hdev, u8 cmd) >> > > > > > +static int qca_send_power_pulse(struct hci_uart *hu, u8 cmd) >> > > > > > { >> > > > > > - struct hci_uart *hu = hci_get_drvdata(hdev); >> > > > > > - struct qca_data *qca = hu->priv; >> > > > > > - struct sk_buff *skb; >> > > > > > + int ret; >> > > > > > >> > > > > > /* These power pulses are single byte command which are sent >> > > > > > * at required baudrate to wcn3990. On wcn3990, we have an external >> > > > > > @@ -1029,19 +1027,16 @@ static int qca_send_power_pulse(struct hci_dev *hdev, u8 cmd) >> > > > > > * save power. Disabling hardware flow control is mandatory while >> > > > > > * sending power pulses to SoC. >> > > > > > */ >> > > > > > - bt_dev_dbg(hdev, "sending power pulse %02x to SoC", cmd); >> > > > > > - >> > > > > > - skb = bt_skb_alloc(sizeof(cmd), GFP_KERNEL); >> > > > > > - if (!skb) >> > > > > > - return -ENOMEM; >> > > > > > - >> > > > > > + bt_dev_dbg(hu->hdev, "sending power pulse %02x to SoC", cmd); >> > > > > > hci_uart_set_flow_control(hu, true); >> > > > > > + ret = serdev_device_write_buf(hu->serdev, &cmd, sizeof(cmd)); >> > > > > > + if (ret < 0) { >> > > > > > + bt_dev_err(hu->hdev, "failed to send power pulse %02x to SoC", >> > > > > > + cmd); >> > > > > > + return ret; >> > > > > > + } >> > > > > > >> > > > > > - skb_put_u8(skb, cmd); >> > > > > > - hci_skb_pkt_type(skb) = HCI_COMMAND_PKT; >> > > > > > - >> > > > > > - skb_queue_tail(&qca->txq, skb); >> > > > > > - hci_uart_tx_wakeup(hu); >> > > > > > + serdev_device_wait_until_sent(hu->serdev, 0); >> > > > >> > > > Again, do you really want to wait indefinitely here? >> > > > >> > > [Bala]: these commands are mandatory to turn ON or OFF the chip. >> > > so blocking to the max time is required. >> > > these commands are sent during the BT chip ON & OFF. >> > > in the latest series, i have flushed the uart before sending >> > > this >> > > commands >> > > so the uart FIFO(as just opened the port before calling this >> > > function) or the circular >> > > buffer will be empty and also i am disabling the flow >> > > control too. >> > > https://patchwork.kernel.org/patch/10744435/ >> > >> > The commands may be mandatory for switching the chip on or off, but >> > what is better if there is a problem with sending them (e.g. a buggy >> > UART driver): >> > >> > 1. wait a reasonable time, report an error >> > 2. wait forever >> > >> > ? >> > >> > If the single byte command couldn't be sent after a few milliseconds, >> > it likely never will, waiting forever doesn't fix that. An error >> > report at least provides some information about the problem and the >> > driver is in a not-hanging state. >> > >> > Cheers >> > >> > Matthias >> >> [Bala]: will update this with a bound TIMEOUT value. But >> wait_until_sent() >> is void return >> type how could we know that the data is sent out on the lines. > > Good point, I didn't check and expected it to return an error. If you > feel really motivated and have maintainer support you could possibly > change the API, however it seems this would be a somewhat larger > change. > > I guess the next best thing to do is to proceed as if all data was > sent and if there was a problem it will likely manifest through > another error (especially for the ON pulse), which still seems better > than a hanging driver. > > Cheers > > Matthias [Bala]: sure, will add the timeout to one second and if data didn't sent to the lines anyways we will get an version command timeouts errors. -- Regards Balakrishna.