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 F2138C54EE9 for ; Wed, 7 Sep 2022 12:21:57 +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=41XuMGP4W2x/8BkqnUdg0btd4UBsV4N66D6CIEDjk1Q=; b=lO+AGcchbQp8wAxcC0czmR7SCq h1sZUrAUk2iBFHRgybm74QOk0Uiekr0YEnn9Vla2kYteFm+IochRe4M+OnM0SI8LGAFljzSFh2O1n AT19ufUVGO87tpJ2ScQz9M+CIKy/d1DhDtMy2wozW1m2ChTt3zQPwFBQhiIWsKvPcl39hLpKJ1Ml4 Xje9KfU5vm+m/1PiygoujNwwmJa0MW8zcr3IZsClMyuhiO844zeijN2unVMwjjQcRXynrS/cvMvYJ DXX+uKlDcm36tBqtkqc1/wLGbLgmherZtvmzeuUe3P/ozynN6saTYqOJx5UhZwx7KmIafr1aFXD5m hyLuNWVg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1oVu3t-0063gX-JH; Wed, 07 Sep 2022 12:21:45 +0000 Received: from mga03.intel.com ([134.134.136.65]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1oVu3q-0063eV-Hu for linux-riscv@lists.infradead.org; Wed, 07 Sep 2022 12:21:44 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1662553302; x=1694089302; h=date:from:to:cc:subject:in-reply-to:message-id: references:mime-version; bh=i5as+3xhYVCZyfsyjas1dxePnfSBwW/4rUe+OF92EJg=; b=ICd76LC06FBuiSMR/pU3r6SZgsncFQtlMgHkien4L61fp6ZsC+EmtKqo 8lCjRgUXoe6+MMikXkF5vmzLd2r0Ctcoy5sa9oeyncdsSIyUchcfzF0V7 cDHLSx5LYA4Bqn7eQbZX5yb5OULplu/7PV4yYJHjv42JKyYdBDvnKdhie hZ297hq4N9TpQukLGF9KvoYAq6iXifYmfR8W+96EphDVqepcrzGLh/KSR noIjlwBPzFENB1tyZZd47b9n7V/l4uh6W8H8g/+sayfRcJzZ4vhBfvVM5 Y9A15CvVYvlyIw2Ax/PgCNVanl7wvZmdqolgC32XHx3/eX5izuRjLFL6v w==; X-IronPort-AV: E=McAfee;i="6500,9779,10462"; a="298172200" X-IronPort-AV: E=Sophos;i="5.93,296,1654585200"; d="scan'208";a="298172200" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 Sep 2022 05:21:39 -0700 X-IronPort-AV: E=Sophos;i="5.93,296,1654585200"; d="scan'208";a="644594732" Received: from dmatouse-mobl.ger.corp.intel.com ([10.251.223.53]) by orsmga008-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 Sep 2022 05:21:30 -0700 Date: Wed, 7 Sep 2022 15:21:28 +0300 (EEST) From: =?ISO-8859-15?Q?Ilpo_J=E4rvinen?= To: Arnd Bergmann cc: Jiri Slaby , Johan Hovold , Greg Kroah-Hartman , 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: <715b40ba-1bcc-4582-bed1-ef41126c7b94@www.fastmail.com> 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="8323329-1356709510-1662553299=:1717" X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220907_052142_659027_AB75E3A8 X-CRM114-Status: GOOD ( 37.82 ) 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. --8323329-1356709510-1662553299=:1717 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8BIT 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. -- i. --8323329-1356709510-1662553299=: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 --8323329-1356709510-1662553299=:1717--