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 49A01C54EE9 for ; Wed, 7 Sep 2022 12:36:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=kRv7KEYteqn0oSHPnzh+TmTgSYCtIAc7SitF8TvLuHU=; b=ZASNOaayIJAxsi SAzVjkBIswyTsFdlD5dMmERbYuxW0SxyfzBEi11gUoprn/Duzg433Sd4fdzskKmn0vqMsWt4JECdC qtOib1bNcXQtAPLW2L3GZPSucMBqiN5NS+rvWQwR83cXCA2/55Xdz084J52a8lMHqYgUhM8udLOdk CuGkDQJPqgubEbBrG/8Ha/nnq/AILX/M72lzBmHCG39hSdYIpN418U7ms9DxW0ctohM42ymxdq6Oi X70BrnX6gxGEzwcVG1O3QTJfqGwqnEgMh+2Xz974ydXOCEfuOWXoVyTKJMfqqYxJHC5+f+Qgvwli2 IIKNJ6kKbEoFgLLwzdXQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1oVuIP-006A8L-MK; Wed, 07 Sep 2022 12:36:45 +0000 Received: from dfw.source.kernel.org ([139.178.84.217]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1oVuIL-006A5E-0U for linux-riscv@lists.infradead.org; Wed, 07 Sep 2022 12:36:42 +0000 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 823BD618F3; Wed, 7 Sep 2022 12:36:40 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4EB65C433D6; Wed, 7 Sep 2022 12:36:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1662554199; bh=QgJtQQyWhXkuOFpCX2/kDd53/jJ10WDfToo3fSGo0qE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=B4esvN0Z0ADEd8fI2c/TyT+AHLjmAv+u7pyIMhLxwtcMZmO6zzeLog2JmBJPNu+2Q vW5yQwciydrFO0UGPT2p8vWrNdrVN4iVPH/lJbFnh+5f9JAilM+zqB7XovXOweJEwR h7u4MPrdV5xPyNEssdrkhbOtkEDjbtA2sWs+VSH8= Date: Wed, 7 Sep 2022 14:36:37 +0200 From: Greg Kroah-Hartman To: Ilpo =?iso-8859-1?Q?J=E4rvinen?= 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 , Andreas =?iso-8859-1?Q?F=E4rber?= , Manivannan Sadhasivam , Russell King , Florian Fainelli , bcm-kernel-feedback-list@broadcom.com, Pali =?iso-8859-1?Q?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 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-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220907_053641_163586_CCECED4D X-CRM114-Status: GOOD ( 45.33 ) 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: , Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org On Wed, Sep 07, 2022 at 03:32:44PM +0300, Ilpo J=E4rvinen wrote: > On Wed, 7 Sep 2022, Greg Kroah-Hartman wrote: > = > > On Wed, Sep 07, 2022 at 03:21:28PM +0300, Ilpo J=E4rvinen wrote: > > > On Wed, 7 Sep 2022, Arnd Bergmann wrote: > > > = > > > > On Wed, Sep 7, 2022, at 12:16 PM, Ilpo J=E4rvinen 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 functi= on in > > > > >> serial-core calling hooks like I had [1] for example. But provid= ed all those > > > > >> CPU workarounds/thunks, it'd be quite expensive to call two func= tions per > > > > >> character. > > > > >> = > > > > >> Or creating a static inline (having =B1 the macro content) and t= he 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@sus= e.cz/ > > > > > > > > > > I second Jiri here. > > > > > > > > > > Saving lines in drivers is not that important compared with all r= emoving = > > > > > 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" varian= t = > > > > > 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 even= tually = > > > > > lead to similar differentiation so e.g. a one-time band-aid simil= arization = > > > > > would not help in the long run. > > > > > > > > > > Also, I don't understand why you see it unreadable when the actua= l 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 h= ardly = > > > > > readable ;-). I agree though there's a learning-curve, albeit sma= ll, 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_cha= rs, > > > > 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 wor= ld. > > = > > 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. Ok, no, I don't understand what Arnd meant here then :( confused, greg k-h _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv