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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 214D3C433DF for ; Sun, 17 May 2020 02:02:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 03B5C206F4 for ; Sun, 17 May 2020 02:02:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726932AbgEQCCa (ORCPT ); Sat, 16 May 2020 22:02:30 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57396 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726880AbgEQCC3 (ORCPT ); Sat, 16 May 2020 22:02:29 -0400 Received: from shards.monkeyblade.net (shards.monkeyblade.net [IPv6:2620:137:e000::1:9]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BB791C061A0C for ; Sat, 16 May 2020 19:02:29 -0700 (PDT) Received: from localhost (unknown [IPv6:2601:601:9f00:477::3d5]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) (Authenticated sender: davem-davemloft) by shards.monkeyblade.net (Postfix) with ESMTPSA id 3EFF012782505; Sat, 16 May 2020 19:02:28 -0700 (PDT) Date: Sat, 16 May 2020 19:02:25 -0700 (PDT) Message-Id: <20200516.190225.342589110126932388.davem@davemloft.net> To: marex@denx.de Cc: netdev@vger.kernel.org, lukas@wunner.de, ynezz@true.cz, yuehaibing@huawei.com Subject: Re: [PATCH V6 00/20] net: ks8851: Unify KS8851 SPI and MLL drivers From: David Miller In-Reply-To: <20200517003354.233373-1-marex@denx.de> References: <20200517003354.233373-1-marex@denx.de> X-Mailer: Mew version 6.8 on Emacs 26.3 Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.5.12 (shards.monkeyblade.net [149.20.54.216]); Sat, 16 May 2020 19:02:28 -0700 (PDT) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Marek Vasut Date: Sun, 17 May 2020 02:33:34 +0200 > The KS8851SNL/SNLI and KS8851-16MLL/MLLI/MLLU are very much the same pieces > of silicon, except the former has an SPI interface, while the later has a > parallel bus interface. Thus far, Linux has two separate drivers for each > and they are diverging considerably. > > This series unifies them into a single driver with small SPI and parallel > bus specific parts. The approach here is to first separate out the SPI > specific parts into a separate file, then add parallel bus accessors in > another separate file and then finally remove the old parallel bus driver. > The reason for replacing the old parallel bus driver is because the SPI > bus driver is much higher quality. What strikes me in these changes is all of the new indirect jumps in the fast paths of TX and RX packet processing. It's just too much for my eyes. :-) Especially in the presence of Spectre mitigations, these costs are quite non-trivial. Seriously, I would recommend that instead of having these small indirect helpers, just inline the differences into two instances of the RX interrupt and the TX handler.