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=-8.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 DB997C433DF for ; Tue, 26 May 2020 21:22:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B473620870 for ; Tue, 26 May 2020 21:22:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="dz9YUIVq" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404257AbgEZVWf (ORCPT ); Tue, 26 May 2020 17:22:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54956 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2403878AbgEZVWe (ORCPT ); Tue, 26 May 2020 17:22:34 -0400 Received: from mail-pg1-x542.google.com (mail-pg1-x542.google.com [IPv6:2607:f8b0:4864:20::542]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 97467C061A0F; Tue, 26 May 2020 14:22:34 -0700 (PDT) Received: by mail-pg1-x542.google.com with SMTP id j21so10675805pgb.7; Tue, 26 May 2020 14:22:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=J/Hxv10p1u+qdYRmsyZWQAn4qMOS/a3PxG600UXIWTM=; b=dz9YUIVqH0AWe3CohewOUedDHc7P0WRC48OTKi6Hn1G0XrQ342WdumVhThTSq6EJrZ QQGgkjgydftJloQ72YDRO1UFfU2WrkuXZBcPOF+MFIUuXYIvPUVNRpjcSVBYi90eAkxp zNJ7jJtIicPBE0o1Yv26fd9A3TR0159Ldl7JmPtYZJXXLae30HNMliuVOFzQo8fTAlwX qPC4F9i0QRas80NXbXP4LneUws9iIxkPebNke5rtjOtWjjT5EZcPcOKVYHAGr9sSZbCl CetiV/4zfVImEr6gUyCI8ty4chlbxynRC/2LxGZq1jxksDXouAe8LxN8Xs/dChjshSXW zV/Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=J/Hxv10p1u+qdYRmsyZWQAn4qMOS/a3PxG600UXIWTM=; b=CKp3aOSDVRuNivg5BWromxiVDPwUGnh7SkJfGnPpMuUFL5G5WtrrK43gvo+B8F2KOX uOvaMkiuoZQvtfkizGRn/V3A1E+/Xa9wdK/znHDv1ufvKEF6kq8xKdK3kIjebE0KZ1fh NhrRrbMus15eppUBam/jjI7Q8SDXBxFn3sLucSS5r6VQMjfojLaxaDb1JObPqNpkWiz2 iuMSir50QIHS8diAAErKgH8ugxzS/Kes01GTyl4tgxL+E5UCbdJnq3zQpeOHPhqPP09Z U8ooEbmjLVxMk7kSqsB0r+iGx1E82YNnAG7/lY7kMqLo2l8nhQD6VnUbxJ02KENoPt4Q LN2w== X-Gm-Message-State: AOAM533SD8Dfz6derpmYlvGyq/zkEzA8AAJT+46er/F7ot7WcZoHz2jE pbk+VxkhuyRb3w293gFeOOhFiKAQ X-Google-Smtp-Source: ABdhPJw5ZHLNuABAPSQsUrd2hg1gAyB5GH2gzGn8cACgk+oCFvL/5+YqQQoh6lc3Dt2UDgsbjLEZow== X-Received: by 2002:a62:e419:: with SMTP id r25mr736849pfh.82.1590528154133; Tue, 26 May 2020 14:22:34 -0700 (PDT) Received: from [10.230.188.43] ([192.19.223.252]) by smtp.gmail.com with ESMTPSA id e13sm391669pfh.19.2020.05.26.14.22.31 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 26 May 2020 14:22:33 -0700 (PDT) Subject: Re: [PATCH net-next 4/4] net: phy: mscc-miim: read poll when high resolution timers are disabled To: Antoine Tenart , davem@davemloft.net, andrew@lunn.ch, hkallweit1@gmail.com Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, alexandre.belloni@bootlin.com, thomas.petazzoni@bootlin.com, allan.nielsen@microchip.com References: <20200526162256.466885-1-antoine.tenart@bootlin.com> <20200526162256.466885-5-antoine.tenart@bootlin.com> From: Florian Fainelli Message-ID: Date: Tue, 26 May 2020 14:22:31 -0700 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Firefox/68.0 Thunderbird/68.8.1 MIME-Version: 1.0 In-Reply-To: <20200526162256.466885-5-antoine.tenart@bootlin.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 5/26/2020 9:22 AM, Antoine Tenart wrote: > The driver uses a read polling mechanism to check the status of the MDIO > bus, to know if it is ready to accept next commands. This polling > mechanism uses usleep_delay() under the hood between reads which is fine > as long as high resolution timers are enabled. Otherwise the delays will > end up to be much longer than expected. > > This patch fixes this by using udelay() under the hood when > CONFIG_HIGH_RES_TIMERS isn't enabled. This increases CPU usage. > > Signed-off-by: Antoine Tenart > --- > drivers/net/phy/Kconfig | 3 ++- > drivers/net/phy/mdio-mscc-miim.c | 22 +++++++++++++++++----- > 2 files changed, 19 insertions(+), 6 deletions(-) > > diff --git a/drivers/net/phy/Kconfig b/drivers/net/phy/Kconfig > index 2a32f26ead0b..047c27087b10 100644 > --- a/drivers/net/phy/Kconfig > +++ b/drivers/net/phy/Kconfig > @@ -184,7 +184,8 @@ config MDIO_MSCC_MIIM > depends on HAS_IOMEM > help > This driver supports the MIIM (MDIO) interface found in the network > - switches of the Microsemi SoCs > + switches of the Microsemi SoCs; it is recommended to switch on > + CONFIG_HIGH_RES_TIMERS > > config MDIO_MVUSB > tristate "Marvell USB to MDIO Adapter" > diff --git a/drivers/net/phy/mdio-mscc-miim.c b/drivers/net/phy/mdio-mscc-miim.c > index aed9afa1e8f1..11f583fd4611 100644 > --- a/drivers/net/phy/mdio-mscc-miim.c > +++ b/drivers/net/phy/mdio-mscc-miim.c > @@ -39,13 +39,25 @@ struct mscc_miim_dev { > void __iomem *phy_regs; > }; > > +/* When high resolution timers aren't built-in: we can't use usleep_range() as > + * we would sleep way too long. Use udelay() instead. > + */ > +#define mscc_readl_poll_timeout(addr, val, cond, delay_us, timeout_us) \ > +({ \ > + if (!IS_ENABLED(CONFIG_HIGH_RES_TIMERS)) \ > + readl_poll_timeout_atomic(addr, val, cond, delay_us, \ > + timeout_us); \ > + readl_poll_timeout(addr, val, cond, delay_us, timeout_us); \ > +}) > + I would make this a regular function which would not harm the compiler's ability to optimize it, but would give you type checking. With that fixed: Reviewed-by: Florian Fainelli -- Florian