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=-12.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 1249CC4361B for ; Tue, 8 Dec 2020 20:57:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E0EE323AFE for ; Tue, 8 Dec 2020 20:57:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729539AbgLHU5F (ORCPT ); Tue, 8 Dec 2020 15:57:05 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43550 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727988AbgLHU5F (ORCPT ); Tue, 8 Dec 2020 15:57:05 -0500 Received: from mail-ed1-x541.google.com (mail-ed1-x541.google.com [IPv6:2a00:1450:4864:20::541]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EA9FCC0613CF for ; Tue, 8 Dec 2020 12:56:24 -0800 (PST) Received: by mail-ed1-x541.google.com with SMTP id b73so19004712edf.13 for ; Tue, 08 Dec 2020 12:56:24 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=6DdKBi1cgyoljGzBWCPffDWHeqJxmio3GBFfS+NIfpY=; b=Z3uH/CLDgd4c8a3xYlBrJg+iZwA7p/MEKgN6YvCW3b+0aUn2POp3Y7BT2rNa/HG9a0 LtLgfUOutgciB9Tl1ovHmN8PDhy8YhHFvR4mmKcckckrifYyYTU88EaHbhMQzmZUgLt/ 5ka33ut76coqFuFP8Xo1AdY1YZsNlMVjz8CAMVFG8z42Yynmk3NtNh9cU4wqtVC0Xzhh 9M7epuoYWSGEuCCdzehdfQGbDNsrHEKpsIIEe5fXPFhNcTDlCel2AvYSe/8qeP8KS3G6 cwFyjF8yc+mLZEo6gGFr3kDn6amVQVIouA4ZAKMIN8CefaPFgod6VRAloIfsfSevkhcf 8uOQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=6DdKBi1cgyoljGzBWCPffDWHeqJxmio3GBFfS+NIfpY=; b=dh2AidehyOLn6E2W/boluH9nYAai3W644hjFioFczMDlio5/2J+QjeFvQmMEvwN2tb 5GRGArwhDSy2Utgmeo9nn2DG0sYOXLDaE8T3lvamMpaPZmubYTFOJeWnSrQ0jnz39TTN FPJolSid3yCKF0DpdV/NVW4ayTTl2ybvuMxoxNFGhPSWuo53yTVsngc4Eg7Ai4Re/lsM gCPQj0bQeJQ9kdG7mOEw3452qq0AoNKFsddTOVcFs5hMNhiaPgqiOm0TieExyFvrWlah y6bQwK3Wk38FB4xzt+ZMTFOsUCVQU0ZwRokfUFylDTpYYxmxJz9HarQT7aLv7NPsVYf5 YqCg== X-Gm-Message-State: AOAM530DUMyUhcTgE3Yp7/lG4o7KcNJhLbVpR5AI60I6bEwJorjiysWr 3hJbW451f0FlX+cBvGGH1NA= X-Google-Smtp-Source: ABdhPJxa21e6yip2uA76uaSWYELHefCaNi/orwRfb/Csqj7vcOGqrq4tdzivCuwG1N34Xep7QlME1A== X-Received: by 2002:a05:6402:491:: with SMTP id k17mr26388321edv.370.1607460983588; Tue, 08 Dec 2020 12:56:23 -0800 (PST) Received: from skbuf ([188.25.2.120]) by smtp.gmail.com with ESMTPSA id l1sm9130705eje.12.2020.12.08.12.56.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 08 Dec 2020 12:56:23 -0800 (PST) Date: Tue, 8 Dec 2020 22:56:21 +0200 From: Vladimir Oltean To: DENG Qingfang Cc: netdev@vger.kernel.org, linux-mediatek@lists.infradead.org, Sean Wang , Landen Chao , Andrew Lunn , Vivien Didelot , Florian Fainelli , "David S . Miller" , Jakub Kicinski , Matthias Brugger , Russell King , Frank Wunderlich Subject: Re: [PATCH net-next] net: dsa: mt7530: support setting ageing time Message-ID: <20201208205621.2xxscilegk4k4t4g@skbuf> References: <20201208070028.3177-1-dqfext@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201208070028.3177-1-dqfext@gmail.com> Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Tue, Dec 08, 2020 at 03:00:28PM +0800, DENG Qingfang wrote: > MT7530 has a global address age control register, so use it to set > ageing time. > > The applied timer is (AGE_CNT + 1) * (AGE_UNIT + 1) seconds > > Signed-off-by: DENG Qingfang > --- > drivers/net/dsa/mt7530.c | 41 ++++++++++++++++++++++++++++++++++++++++ > drivers/net/dsa/mt7530.h | 13 +++++++++++++ > 2 files changed, 54 insertions(+) > > diff --git a/drivers/net/dsa/mt7530.c b/drivers/net/dsa/mt7530.c > index 6408402a44f5..99bf8fed6536 100644 > --- a/drivers/net/dsa/mt7530.c > +++ b/drivers/net/dsa/mt7530.c > @@ -870,6 +870,46 @@ mt7530_get_sset_count(struct dsa_switch *ds, int port, int sset) > return ARRAY_SIZE(mt7530_mib); > } > > +static int > +mt7530_set_ageing_time(struct dsa_switch *ds, unsigned int msecs) > +{ > + struct mt7530_priv *priv = ds->priv; > + unsigned int secs = msecs / 1000; > + unsigned int tmp_age_count; > + unsigned int error = -1; > + unsigned int age_count; > + unsigned int age_unit; > + > + /* Applied timer is (AGE_CNT + 1) * (AGE_UNIT + 1) seconds */ > + if (secs < 1 || secs > (AGE_CNT_MAX + 1) * (AGE_UNIT_MAX + 1)) > + return -ERANGE; > + > + /* iterate through all possible age_count to find the closest pair */ > + for (tmp_age_count = 0; tmp_age_count <= AGE_CNT_MAX; ++tmp_age_count) { > + unsigned int tmp_age_unit = secs / (tmp_age_count + 1) - 1; > + > + if (tmp_age_unit <= AGE_UNIT_MAX) { > + unsigned int tmp_error = secs - > + (tmp_age_count + 1) * (tmp_age_unit + 1); > + > + /* found a closer pair */ > + if (error > tmp_error) { > + error = tmp_error; > + age_count = tmp_age_count; > + age_unit = tmp_age_unit; > + } I feel that the error calculation is just snake oil. This would be enough: if (tmp_age_unit <= AGE_UNIT_MAX) break; Explanation: You are given a number X, and must find A and B such that the error E = |(A x B) - X| should be minimum, with 1 <= A <= A_max 1 <= B <= B_max It is logical to try with A=1 first. If X / A <= B_max, then of course, B = X / 1, and the error E is 0. If that doesn't work out, and B > B_max, then you go to A=2. That gives you another B = X / 2, and the error E is 1. You check again if B <= B_max. If it is, that's your answer. B = X / 2, with an error E of 1. You get my point. Iterating ascendingly through A, and calculating B as X / A, already gives you the smallest error as soon as it satisfies the B <= B_max requirement. > + > + /* found the exact match, so break the loop */ > + if (!error) > + break; > + } > + } > + > + mt7530_write(priv, MT7530_AAC, AGE_CNT(age_count) | AGE_UNIT(age_unit)); > + > + return 0; > +} > + > static void mt7530_setup_port5(struct dsa_switch *ds, phy_interface_t interface) > { > struct mt7530_priv *priv = ds->priv; > @@ -2564,6 +2604,7 @@ static const struct dsa_switch_ops mt7530_switch_ops = { > .phy_write = mt753x_phy_write, > .get_ethtool_stats = mt7530_get_ethtool_stats, > .get_sset_count = mt7530_get_sset_count, > + .set_ageing_time = mt7530_set_ageing_time, > .port_enable = mt7530_port_enable, > .port_disable = mt7530_port_disable, > .port_change_mtu = mt7530_port_change_mtu, > diff --git a/drivers/net/dsa/mt7530.h b/drivers/net/dsa/mt7530.h > index ee3523a7537e..32d8969b3ace 100644 > --- a/drivers/net/dsa/mt7530.h > +++ b/drivers/net/dsa/mt7530.h > @@ -161,6 +161,19 @@ enum mt7530_vlan_egress_attr { > MT7530_VLAN_EGRESS_STACK = 3, > }; > > +/* Register for address age control */ > +#define MT7530_AAC 0xa0 > +/* Disable ageing */ > +#define AGE_DIS BIT(20) > +/* Age count */ > +#define AGE_CNT_MASK GENMASK(19, 12) > +#define AGE_CNT_MAX 0xff > +#define AGE_CNT(x) (AGE_CNT_MASK & ((x) << 12)) > +/* Age unit */ > +#define AGE_UNIT_MASK GENMASK(11, 0) > +#define AGE_UNIT_MAX 0xfff > +#define AGE_UNIT(x) (AGE_UNIT_MASK & (x)) > + > /* Register for port STP state control */ > #define MT7530_SSP_P(x) (0x2000 + ((x) * 0x100)) > #define FID_PST(x) ((x) & 0x3) > -- > 2.25.1 >