Date: Sun, 4 Mar 2018 09:07:05 +1100 (EST) From: Bruce Evans <brde@optusnet.com.au> To: Ian Lepore <ian@freebsd.org> Cc: Konstantin Belousov <kostikbel@gmail.com>, Hans Petter Selasky <hselasky@freebsd.org>, src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r330352 - in head/sys/compat/linuxkpi/common: include/linux src Message-ID: <20180304083915.E6774@besplex.bde.org> In-Reply-To: <1520110970.23690.20.camel@freebsd.org> References: <201803031854.w23IsHxm086835@repo.freebsd.org> <1520104482.23690.15.camel@freebsd.org> <20180303204913.GI3194@kib.kiev.ua> <1520110970.23690.20.camel@freebsd.org>
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On Sat, 3 Mar 2018, Ian Lepore wrote: > On Sat, 2018-03-03 at 22:49 +0200, Konstantin Belousov wrote: >> ,,, >> BTW mstosbt() and other functions have weird bracing in the formula. I >> think that the formula as calculated by the C operator precedence is >> fine, i.e. multiplication is done before right shift. But the bracing >> is redundand then, because the '()' pair next to the return () braces by >> inclusion is tautological. >> > > Oh, on looking closer, it's not a paste-o, I just didn't put the > closing paren where I had intended to for making it clear the shift > happens last. =A0(So almost everyone except me is still going to think a > fix has redundant parens.) It is a good example of how redundant parentheses reduce readability. Redundant parentheses make the non-redundant parentheses hard to see. The most important ones are for _ms * (x / 500) (where x =3D ((uint64_t)1 << 63)). These are needed since the natural expression _ms * x / 500 would overflow since it is evaluated left to right. Then you want to add redundant parentheses for _ms * (x / 500) >> 32, although both left to right evaluation and operator precedence work right for that. Then style(9) requires redundant parentheses for the return value. Normally I would parenthesize x * y >> z since I don't remember the precedence of '>>' and suspect it is broken (*), but here there are too many other parentheses. (*) The precedence of '>>' is indeed broken. It is like a division operato= r so should be at the same level or 1 lower. But it is 2 lower (+ and - are in between). So x + y * z means x + (y * z), but x + y >> z means (x + y) >> z. So x + (y >> z) needs parentheses, and (x + y) >> z should be parenthesized since it is surprising that its parentheses are redundant. Bruce From owner-svn-src-head@freebsd.org Sat Mar 3 22:10:17 2018 Return-Path: <owner-svn-src-head@freebsd.org> Delivered-To: svn-src-head@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 42C74F4093A; Sat, 3 Mar 2018 22:10:17 +0000 (UTC) (envelope-from ian@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client CN "mxrelay.nyi.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id DD3CA7903D; Sat, 3 Mar 2018 22:10:16 +0000 (UTC) (envelope-from ian@FreeBSD.org) Received: from repo.freebsd.org (repo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:0]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id CED5346C1; Sat, 3 Mar 2018 22:10:16 +0000 (UTC) (envelope-from ian@FreeBSD.org) Received: from repo.freebsd.org ([127.0.1.37]) by repo.freebsd.org (8.15.2/8.15.2) with ESMTP id w23MAG1j083205; Sat, 3 Mar 2018 22:10:16 GMT (envelope-from ian@FreeBSD.org) Received: (from ian@localhost) by repo.freebsd.org (8.15.2/8.15.2/Submit) id w23MAGXV083204; Sat, 3 Mar 2018 22:10:16 GMT (envelope-from ian@FreeBSD.org) Message-Id: <201803032210.w23MAGXV083204@repo.freebsd.org> X-Authentication-Warning: repo.freebsd.org: ian set sender to ian@FreeBSD.org using -f From: Ian Lepore <ian@FreeBSD.org> Date: Sat, 3 Mar 2018 22:10:16 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r330360 - head/share/man/man9 X-SVN-Group: head X-SVN-Commit-Author: ian X-SVN-Commit-Paths: head/share/man/man9 X-SVN-Commit-Revision: 330360 X-SVN-Commit-Repository: base MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.25 Precedence: list List-Id: SVN commit messages for the src tree for head/-current <svn-src-head.freebsd.org> List-Unsubscribe: <https://lists.freebsd.org/mailman/options/svn-src-head>, <mailto:svn-src-head-request@freebsd.org?subject=unsubscribe> List-Archive: <http://lists.freebsd.org/pipermail/svn-src-head/>; List-Post: <mailto:svn-src-head@freebsd.org> List-Help: <mailto:svn-src-head-request@freebsd.org?subject=help> List-Subscribe: <https://lists.freebsd.org/mailman/listinfo/svn-src-head>, <mailto:svn-src-head-request@freebsd.org?subject=subscribe> X-List-Received-Date: Sat, 03 Mar 2018 22:10:17 -0000 Author: ian Date: Sat Mar 3 22:10:16 2018 New Revision: 330360 URL: https://svnweb.freebsd.org/changeset/base/330360 Log: Minor (mostly) wording changes. Modified: head/share/man/man9/fdt_pinctrl.9 Modified: head/share/man/man9/fdt_pinctrl.9 ============================================================================== --- head/share/man/man9/fdt_pinctrl.9 Sat Mar 3 21:50:55 2018 (r330359) +++ head/share/man/man9/fdt_pinctrl.9 Sat Mar 3 22:10:16 2018 (r330360) @@ -28,7 +28,7 @@ .\" .\" $FreeBSD$ .\" -.Dd March 2, 2018 +.Dd March 3, 2018 .Dt fdt_pinctrl 9 .Os .Sh NAME @@ -50,15 +50,17 @@ provides an API for manipulating I/O pin configuration pinmux controllers and pinmux clients. On the controller side, the standard newbus probe and attach methods are implemented. -This driver also implements the -.Fn fdt_pinctrl_configure -method, in which it calls the +As part of handling attach, it calls the .Fn fdt_pinctrl_register function to register itself as a pinmux controller. Then .Fn fdt_pinctrl_configure_tree is used to walk the device tree and configure pins specified by the pinctrl-0 property for all active devices. +The driver also implements the +.Fn fdt_pinctrl_configure +method, which allows client devices to change their +pin configurations after startup. If a client device requires a pin configuration change at some point of its lifecycle, it uses the .Fn fdt_pinctrl_configure @@ -84,14 +86,9 @@ registers a pinctrl driver so that it can be used by o .Fn fdt_pinctrl_configure or .Fn fdt_pinctrl_configure_by_name . -The -.Fa pinprop -argument is the name of a property that -identifies each descendant of the pinctrl -node. -The pinctrl node is a pin configuration -node whose xref phandle can be passed to -.Fn FDT_PINCTRL_CONFIGURE . +It also registers each child node of the pinctrl driver's node which contains +a property with the name given in +.Fa pinprop . If .Fa pinprop is
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