From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from vps0.lunn.ch (vps0.lunn.ch [156.67.10.101]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7D2B8391E41; Sat, 21 Mar 2026 15:29:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=156.67.10.101 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774106942; cv=none; b=MzqTadXWrdWZ8aoHNuOH23sQLq/Vvt6nB1I0lH6Ck0XJqet0DLkfMa2qj9J8HGQqGPfCqiEL65s1eqUywoHumXW/yFtMkIHuClig/yy7Bh3XXdOBoWymkrmGwcChfpWeOpLWPnOhb+0+pdUFBS5cxOW5SN0fMpnCFgXbu9jUK10= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774106942; c=relaxed/simple; bh=4CMZtdrUkeHipUTfXOQB1nOArw6Y9HSJFvn3EVDhXyk=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=pipUhBVfWpx12RhCvGrKOSAlypWVb3HOG1oIQ9sgtM9GMEhLpXX47WxmHRMeqmhVP75mB7toT/sEmJRkM3EJIefgvyf7My2FvNd26i8a2aN+3Qx18trDIt7B7CH5JlZKjejd0H/SuITthww4gRfHoI35CFWtXz9Q8XET40teOmo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=lunn.ch; spf=pass smtp.mailfrom=lunn.ch; dkim=pass (1024-bit key) header.d=lunn.ch header.i=@lunn.ch header.b=NXQjXmSw; arc=none smtp.client-ip=156.67.10.101 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=lunn.ch Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=lunn.ch Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=lunn.ch header.i=@lunn.ch header.b="NXQjXmSw" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lunn.ch; s=20171124; h=In-Reply-To:Content-Disposition:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:From:Sender:Reply-To:Subject: Date:Message-ID:To:Cc:MIME-Version:Content-Type:Content-Transfer-Encoding: Content-ID:Content-Description:Content-Disposition:In-Reply-To:References; bh=6AP4cI1zcL0d79rvKwxclRXlEkH2NVlrTTHSANQpKdw=; b=NXQjXmSwx/TN8qJjeUwyuQbicK m1Xnpl7EDZuRnQXY+ktfgXE4ykTpvgSi/MMCxvYwz5A/prZjWHF2RMG3RzaJ4C6E/YRRSbkm4co5U llb+laF/WPbbZTUtXndQnpvW+eoWcQ01/fBx8pH12Sdu5mSRppR8NjgJyMs0FPX1M87I=; Received: from andrew by vps0.lunn.ch with local (Exim 4.94.2) (envelope-from ) id 1w3yFw-00CizW-4p; Sat, 21 Mar 2026 16:28:52 +0100 Date: Sat, 21 Mar 2026 16:28:52 +0100 From: Andrew Lunn To: Daniel Golle Cc: Vladimir Oltean , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Frank Wunderlich , Chad Monroe , Cezary Wilmanski , Liang Xu , "Benny (Ying-Tsan) Weng" , Jose Maria Verdu Munoz , Avinash Jayaraman , John Crispin Subject: Re: [PATCH net-next 2/2] net: dsa: mxl862xx: use RST_DATA to skip writing zero words Message-ID: <279eca3d-e067-4d0c-ad2d-9c989d7801ea@lunn.ch> References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Sat, Mar 21, 2026 at 05:20:14AM +0000, Daniel Golle wrote: > Issue the firmware's RST_DATA command before writing data payloads that > contain many zero words. RST_DATA zeroes both the firmware's internal > buffer and the MMD data registers in a single command, allowing the > driver to skip individual MDIO writes for zero-valued words. This > reduces bus traffic for the common case where API structs have many > unused or default-zero fields. > > The optimization is applied when at least 5 zero words are found in the > payload, roughly the break-even point against the cost of the extra > RST_DATA command round-trip. Reviewed-by: Andrew Lunn Andrew