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=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no 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 4B532C2BB1D for ; Tue, 7 Apr 2020 09:41:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 12C5A2074F for ; Tue, 7 Apr 2020 09:41:20 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=mg.codeaurora.org header.i=@mg.codeaurora.org header.b="NpfCjwCh" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726720AbgDGJlT (ORCPT ); Tue, 7 Apr 2020 05:41:19 -0400 Received: from mail27.static.mailgun.info ([104.130.122.27]:22954 "EHLO mail27.static.mailgun.info" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725883AbgDGJlT (ORCPT ); Tue, 7 Apr 2020 05:41:19 -0400 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1586252478; h=Content-Transfer-Encoding: Content-Type: In-Reply-To: MIME-Version: Date: Message-ID: References: Cc: To: From: Subject: Sender; bh=++wZMu6+upyOo/X2jGPlQvmS8PlK2mzO0cecdjSV+I8=; b=NpfCjwCh46lY7MgDze7kW8VBpgsvSzInYvLn11hmo85NQbdOKu7hI8JaMD6GAjzy+1NZoiTz KpzEjRXITZHFQm/pjidTNlT8WDO4IuZwVtSnapyY7e7qVgGa3qdSZPBMISRoBFPPAHr8EMGj Zlk2UYdlJpOZBUmJDs5HKlNdRRY= X-Mailgun-Sending-Ip: 104.130.122.27 X-Mailgun-Sid: WyIzZmY0MiIsICJsaW51eC1zZXJpYWxAdmdlci5rZXJuZWwub3JnIiwgImJlOWU0YSJd Received: from smtp.codeaurora.org (ec2-35-166-182-171.us-west-2.compute.amazonaws.com [35.166.182.171]) by mxa.mailgun.org with ESMTP id 5e8c4aac.7fcfe2b38298-smtp-out-n03; Tue, 07 Apr 2020 09:41:00 -0000 (UTC) Received: by smtp.codeaurora.org (Postfix, from userid 1001) id 11AB9C44791; Tue, 7 Apr 2020 09:40:58 +0000 (UTC) Received: from [192.168.0.6] (unknown [183.83.138.47]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: akashast) by smtp.codeaurora.org (Postfix) with ESMTPSA id 39832C43636; Tue, 7 Apr 2020 09:40:52 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 39832C43636 Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; spf=none smtp.mailfrom=akashast@codeaurora.org Subject: Re: [PATCH V3 6/8] tty: serial: qcom_geni_serial: Add interconnect support From: Akash Asthana To: Matthias Kaehlcke Cc: gregkh@linuxfoundation.org, agross@kernel.org, bjorn.andersson@linaro.org, wsa@the-dreams.de, broonie@kernel.org, mark.rutland@arm.com, robh+dt@kernel.org, georgi.djakov@linaro.org, linux-i2c@vger.kernel.org, linux-spi@vger.kernel.org, devicetree@vger.kernel.org, swboyd@chromium.org, mgautam@codeaurora.org, linux-arm-msm@vger.kernel.org, linux-serial@vger.kernel.org, dianders@chromium.org, evgreen@chromium.org References: <1585652976-17481-1-git-send-email-akashast@codeaurora.org> <1585652976-17481-7-git-send-email-akashast@codeaurora.org> <20200331193949.GK199755@google.com> Message-ID: <694f2664-3ef2-b3a6-c447-c33086172b02@codeaurora.org> Date: Tue, 7 Apr 2020 15:10:50 +0530 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US Sender: linux-serial-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-serial@vger.kernel.org Hi Matthias, >>>     static const struct uart_ops qcom_geni_console_pops = { >>> @@ -1304,6 +1315,17 @@ static int qcom_geni_serial_probe(struct >>> platform_device *pdev) >>>               return -ENOMEM; >>>       } >>>   +    ret = geni_icc_get(&port->se, "qup-core", "qup-config", NULL); >>> +    if (ret) >>> +        return ret; >>> +    /* Set the bus quota to a reasonable value */ >>> +    port->se.to_core.avg_bw = console ? GENI_DEFAULT_BW : >>> +        Bps_to_icc(CORE_2X_50_MHZ); >>> +    port->se.to_core.peak_bw = console ? GENI_DEFAULT_BW : >>> +        Bps_to_icc(CORE_2X_100_MHZ); >> I'm still unconvinced about the setting of the core bandwidth based on >> whether the port is used as console or not. It could possibly break >> consoles working at speeds > 115kbs and reserve more bandwidth than >> necessary for ports with 'slow' devices. >> >> Why not scale the core bandwidth dynamically? You said earlier that >> there >> is no clear/linear translation of port speed to bandwidth, but you could >> use the same logic that is implicitly used here: >> >>     if (baudrate <= 115200) { >>         avg_bw = GENI_DEFAULT_BW; >>         peak_bw = GENI_DEFAULT_BW; I will make peak_bw = 2 * DEFAULT  to generalize this logic and will factor it out in common driver. Anyway with  peak_bw = GENI_DEFAULT_BW or 2 * GENI_DEFAULT_BW core clock is going to tick at 50 MHz. 9600(19.2 MHz) < GENI_DEFAULT_BW, 2 * GENI_DEFAULT_BW < 2500(50 MHz). Regards, Akash >>     } else { >>         avg_bw = Bps_to_icc(CORE_2X_50_MHZ); >>         peak_bw = Bps_to_icc(CORE_2X_100_MHZ); >>     } >> >> This would be more robust, power efficient and future readers of the >> code don't have to wonder "why is the console special?" when our >> discussions on this will be long forgotten. > > Okay, I will add this piece of code in set_termios call of the driver > because I don't have baudrate information during probe. It covers the > console case mentioned in probe function. > > Regards, > > Akash > -- The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,\na Linux Foundation Collaborative Project