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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id F0DDFC38145 for ; Wed, 7 Sep 2022 12:33:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Type:MIME-Version: References:Message-ID:In-Reply-To:Subject:cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=4b93kTA2Ycpc/wtDj3iDUP33GJO5QnjosLdhLBFsMMA=; b=Ve9OkFUKJJnJTyTwCc7/pSFxbz wTLBkUJsv3d3ejypvTa2YxqS0z9ZSrKF8LBIJst2B0Z7l3Jqx9WdtXtwMnu0NuK94Hihz9MZ1vlqJ dMVcu4abYaJE8foAhmnS9YQZqw+2kRiTIS3xtLgc8mtxrrM9OwZPFlUzrMFYeUnZ9NQqeTheJoyFn uBlHE1ubTU8QWLBTDrpFM59eaMzghi7U93Qln++fIrtgsWiaPw2p1QtJsEgX0FmsAn75ubOzLNFap PR8MeTNoQJRXmK2x/Ci83+G/gnLHIOhJHMuQ7e4J95l2YKyjoLk+uupR1NBJaHdmhGosUFsKNZZ8j +cjQ5W0A==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1oVuEo-00683V-LV; Wed, 07 Sep 2022 12:33:02 +0000 Received: from mga06b.intel.com ([134.134.136.31] helo=mga06.intel.com) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1oVuEl-0067ye-FU for linux-riscv@lists.infradead.org; Wed, 07 Sep 2022 12:33:01 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1662553979; x=1694089979; h=date:from:to:cc:subject:in-reply-to:message-id: references:mime-version; bh=xCXSpxCUXSZyXl18Q11gypEzlpbTjfZc+Q3TQqCe31A=; b=aNmd32rS7lQNQHLN/ef83s0YksgyklyD6857tSNRfg/EM4jtxTviQblr s/7AOcstITmq795e90A98O3vUrdk13qalOe+ED6ZjgkEdah5T23hXe9qk iIT7MaRw0npcWOGps4NGuOugHdeSMkH/50NJVeGlAvtGKI7J6El3dhSyO 65zs0HPeVcEV4MIdwnQsM6DjRhFbD2TXZ3MIF+MtBLw4RStkwN1QUvMUi wharL7A6LnW0bjzyShF3LExK0IZML7gQGXpf9AksMATkg0X0TD3aCtyur 1KACRd0p4u0TqM/wkcO5Au06mzdxR9N2bdoMnrQ1qGzjNHS9sm32PmmsD w==; X-IronPort-AV: E=McAfee;i="6500,9779,10462"; a="358572827" X-IronPort-AV: E=Sophos;i="5.93,296,1654585200"; d="scan'208";a="358572827" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by orsmga104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 Sep 2022 05:32:53 -0700 X-IronPort-AV: E=Sophos;i="5.93,296,1654585200"; d="scan'208";a="676166942" Received: from dmatouse-mobl.ger.corp.intel.com ([10.251.223.53]) by fmsmga008-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 Sep 2022 05:32:45 -0700 Date: Wed, 7 Sep 2022 15:32:44 +0300 (EEST) From: =?ISO-8859-15?Q?Ilpo_J=E4rvinen?= To: Greg Kroah-Hartman cc: Arnd Bergmann , Jiri Slaby , Johan Hovold , linux-serial , LKML , Tobias Klauser , Richard Genoud , Nicolas Ferre , Alexandre Belloni , Claudiu Beznea , Vladimir Zapolskiy , Liviu Dudau , Sudeep Holla , Lorenzo Pieralisi , Shawn Guo , Sascha Hauer , Pengutronix Kernel Team , Fabio Estevam , NXP Linux Team , =?ISO-8859-15?Q?Andreas_F=E4rber?= , Manivannan Sadhasivam , Russell King , Florian Fainelli , bcm-kernel-feedback-list@broadcom.com, =?ISO-8859-15?Q?Pali_Roh=E1r?= , Kevin Cernekee , Palmer Dabbelt , Paul Walmsley , Orson Zhai , Baolin Wang , Chunyan Zhang , Patrice Chotard , linux-riscv@lists.infradead.org Subject: Re: [PATCH v3 0/4] tty: TX helpers In-Reply-To: Message-ID: References: <20220906104805.23211-1-jslaby@suse.cz> <4e9b4471-a6f2-4b16-d830-67d253ae4e6a@linux.intel.com> <715b40ba-1bcc-4582-bed1-ef41126c7b94@www.fastmail.com> MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="8323329-1383753858-1662553973=:1717" X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220907_053259_628337_DFC3E2D5 X-CRM114-Status: GOOD ( 42.77 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. --8323329-1383753858-1662553973=:1717 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8BIT On Wed, 7 Sep 2022, Greg Kroah-Hartman wrote: > On Wed, Sep 07, 2022 at 03:21:28PM +0300, Ilpo Järvinen wrote: > > On Wed, 7 Sep 2022, Arnd Bergmann wrote: > > > > > On Wed, Sep 7, 2022, at 12:16 PM, Ilpo Järvinen wrote: > > > > On Wed, 7 Sep 2022, Jiri Slaby wrote: > > > >> On 06. 09. 22, 13:30, Johan Hovold wrote: > > > >> > On Tue, Sep 06, 2022 at 12:48:01PM +0200, Jiri Slaby wrote: > > > >> > NAK > > > >> > > > >> I'd love to come up with something nicer. That would be a function in > > > >> serial-core calling hooks like I had [1] for example. But provided all those > > > >> CPU workarounds/thunks, it'd be quite expensive to call two functions per > > > >> character. > > > >> > > > >> Or creating a static inline (having ± the macro content) and the hooks as > > > >> parameters and hope for optimizations to eliminate thunks (also suggested in > > > >> the past [1]). > > > >> > > > >> [1] https://lore.kernel.org/all/20220411105405.9519-1-jslaby@suse.cz/ > > > > > > > > I second Jiri here. > > > > > > > > Saving lines in drivers is not that important compared with all removing > > > > all the variants of the same thing that have crept there over the years. > > > > > > > > I suspect the main reason for the variants is that everybody just used > > > > other drivers as examples and therefore we've a few "main" variant > > > > branches depending on which of the drivers was used as an example for the > > > > other. That is hardly a good enough reason to keep them different and as > > > > long as each driver keeps its own function for this, it will eventually > > > > lead to similar differentiation so e.g. a one-time band-aid similarization > > > > would not help in the long run. > > > > > > > > Also, I don't understand why you see it unreadable when the actual code is > > > > out in the open in that macro. It's formatted much better than e.g. > > > > read_poll_timeout() if you want an example of something that is hardly > > > > readable ;-). I agree though there's a learning-curve, albeit small, that > > > > it actually creates a function but that doesn't seem to me as big of an > > > > obstacle you seem to think. > > > > > > I think it would help to replace the macro that defines > > > the function with a set of macros that can be used in > > > function bodies. This would avoid the __VA_ARGS__ stuff > > > and allow readers that are unfamiliar with tty drivers to > > > treat it as a function call. > > > > > > So e.g. instead of > > > > > > static DEFINE_UART_PORT_TX_HELPER_LIMITED(altera_jtaguart_do_tx_chars, > > > true, > > > writel(ch, port->membase + ALTERA_JTAGUART_DATA_REG), > > > ({})); > > > > > > the altera_jtaguart driver would contain a function like > > > > > > static int altera_jtaguart_do_tx_chars(struct uart_port *port, > > > unsigned int count) > > > { > > > char ch; > > > > > > return uart_port_tx_helper_limited(port, ch, count, true, > > > writel(ch, port->membase + ALTERA_JTAGUART_DATA_REG), > > > ({})); > > > } > > > > > > or some variation of that. It's a few more lines, but those > > > extra lines would help me understand what is actually going on > > > while still avoiding the usual bugs and duplication. > > > > > > If the caller of that function is itself trivial (like > > > serial21285_tx_chars), then the intermediate function can > > > be omitted in order to save some of the extra complexity. > > > > I'd be ok with that. There's still a small startle factor associated to > > passing that writel(...) as an argument to a "function" but it's the same > > for other things such as read_poll_timeout() so not an end of the world. > > That's going to incure the function-pointer-indirection-call for every > character that Jiri's original submission had, so I don't think this is > a very viable solution, sorry. I don't think you got what Arnd meant. It must still be technically a #define because you cannot pass writel(ch, port->membase + ALTERA_JTAGUART_DATA_REG) as an argument to a real function like he did in the example above. It's similar to how read_poll_timeout() and friends are #defines despite being lowercased. -- i. --8323329-1383753858-1662553973=:1717 Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv --8323329-1383753858-1662553973=:1717--