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=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 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 5159BC433DB for ; Fri, 12 Feb 2021 11:29:04 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id EA83364D9C for ; Fri, 12 Feb 2021 11:29:03 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EA83364D9C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=dri-devel-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 595BD6E5A4; Fri, 12 Feb 2021 11:29:03 +0000 (UTC) Received: from mga12.intel.com (mga12.intel.com [192.55.52.136]) by gabe.freedesktop.org (Postfix) with ESMTPS id 223606E59F for ; Fri, 12 Feb 2021 11:29:02 +0000 (UTC) IronPort-SDR: lRWB8wNIaUKyohRtDwvR8Wd803vGO1juE7i400OnjMfsIjUV9GY5YFoGzV/ECLf90/esXSUQW8 8XrzKKrg0YNQ== X-IronPort-AV: E=McAfee;i="6000,8403,9892"; a="161540303" X-IronPort-AV: E=Sophos;i="5.81,173,1610438400"; d="scan'208";a="161540303" Received: from fmsmga006.fm.intel.com ([10.253.24.20]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Feb 2021 03:29:01 -0800 IronPort-SDR: HUg+trz2d5paAqvWN9dd0/75YMfj8GXGjps6WWAjelEU+HN3D9b3SAzc3oppS+4yCZVsnCkfSn gf9WEc+KzwWA== X-IronPort-AV: E=Sophos;i="5.81,173,1610438400"; d="scan'208";a="587438215" Received: from paasikivi.fi.intel.com ([10.237.72.42]) by fmsmga006-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Feb 2021 03:28:58 -0800 Received: from paasikivi.fi.intel.com (localhost [127.0.0.1]) by paasikivi.fi.intel.com (Postfix) with ESMTP id 9631620345; Fri, 12 Feb 2021 13:28:56 +0200 (EET) Date: Fri, 12 Feb 2021 13:28:56 +0200 From: Sakari Ailus To: Petr Mladek Subject: Re: [PATCH v6 1/3] lib/vsprintf: Add support for printing V4L2 and DRM fourccs Message-ID: <20210212112856.GE3@paasikivi.fi.intel.com> References: <20210208200903.28084-1-sakari.ailus@linux.intel.com> <20210208200903.28084-2-sakari.ailus@linux.intel.com> <20210209092032.GC32460@paasikivi.fi.intel.com> <20210209174755.GH32460@paasikivi.fi.intel.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Dave Stevenson , Rasmus Villemoes , Linux Kernel Mailing List , dri-devel , Hans Verkuil , Sergey Senozhatsky , Andy Shevchenko , Steven Rostedt , Laurent Pinchart , Joe Perches , Mauro Carvalho Chehab , Linux Media Mailing List Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" Hi Petr, Thanks for the comments. On Thu, Feb 11, 2021 at 06:14:28PM +0100, Petr Mladek wrote: > On Tue 2021-02-09 19:47:55, Sakari Ailus wrote: > > Hi Andy, > > = > > On Tue, Feb 09, 2021 at 11:58:40AM +0200, Andy Shevchenko wrote: > > > On Tue, Feb 09, 2021 at 11:20:32AM +0200, Sakari Ailus wrote: > > > > On Mon, Feb 08, 2021 at 10:43:30PM +0200, Andy Shevchenko wrote: > > > > > On Mon, Feb 8, 2021 at 10:11 PM Sakari Ailus > > > > > wrote: > > > = > > > ... > > > = > > > > > > + %p4cc BG12 little-endian (0x32314742) > > > > > = > > > > > This misses examples of the (strange) escaping cases and wiped > > > > > whitespaces to make sure everybody understands that 'D 12' will b= e the > > > > > same as 'D1 2' (side note: which I disagree on, perhaps something > > > > > should be added into documentation why). > > > > = > > > > The spaces are expected to be at the end only. I can add such examp= le if > > > > you like. There are no fourcc codes with spaces in the middle in ne= ither > > > > V4L2 nor DRM, and I don't think the expectation is to have them eit= her. > > > = > > > But then the code suggests otherwise. Perhaps we need to extract > > > skip_trailing_spaces() from strim() and use it here. > > = > > But this wouldn't affect the result in this case, would it? > = > Is there any existing implementation that would skip spaces, please? > = > IMHO, this might just hide problems. We should show exactly what > is stored unless anyone explicitly ask for skipping that spaces. I discussed this with Hans and we concluded spaces shouldn't be dropped. Spaces can be present in the codes themselves in any case. > = > > > = > > > ... > > > = > > > > > > +static noinline_for_stack > > > > > > +char *fourcc_string(char *buf, char *end, const u32 *fourcc, > > > > > > + struct printf_spec spec, const char *fmt) > > > > > > +{ > > > > > = > > > > > > + char output[sizeof("(xx)(xx)(xx)(xx) little-endian (0x0= 1234567)")]; > > > > > = > > > > > Do we have any evidence / document / standard that the above form= at is > > > > > what people would find good? From existing practices (I consider = other > > > > > printings elsewhere and users in this series) I find '(xx)' form = for > > > > > hex numbers is weird. The standard practice is to use \xHH (witho= ut > > > > > parentheses). > > > > = > > > > Earlier in the review it was proposed that special handling of code= s below > > > > 32 should be added, which I did. Using the parentheses is apparentl= y an > > > > existing practice elsewhere. > > > = > > > Where? \xHH is quite well established format for escaping. Never hear= d about > > > '(xx)' variant before this very series. > = > > Mauro referred to FourCC codes while reviewing an earlier version of th= is, > > such as RGB(15). > = > This is quite easy to parse. The problem is that it is not clear > whether it is hexa or decimal number. > = > > Does \=D7 imply only the next two characters are hexadecimal? I have to= admit > > I don't remember seeting that, nor \x notation is common. > = > Hmm, the /xyy format might be hard to parse. > = > What about using the same approach as drm_get_format_name()? > I mean printing '?' when the character is not printable. > The exact value is printed later anyway. > = > The advantage is that it will always printk 4 characters. "?" can be expanded by the shell. We (me and Hans) both though a dot (".") would be good. These aren't going to be present in valid fourcc codes in any case. > = > = > > > > Note that neither DRM nor V4L2 currently has such fourcc codes curr= ently. > > > = > > > ... > > > = > > > > > > + p =3D special_hex_number(p, output + sizeof(output) - 2= , *fourcc, > > > > > > + sizeof(u32)); > > > > > = > > > > > This is perfectly one line (in this file we have even longer line= s). > = > Ailus, please do not take this as a criticism of your patch. > I understand that it might have sounded like this but Andy did > not mean it. > = > Andy prefers slightly longer lines over wrapping only few characters. > It makes sense to me. There are more people with the same opinion. > Even checkpatch.pl tolerates lines up to 100 characters these days. > = > Of course, this is a subsystem specific preference. You did not have > any chance to know it. There is no need to fight over it. Fair enough; I can violate the coding style a little in v7. -- = Kind regards, Sakari Ailus _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel