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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B69C0C43217 for ; Mon, 14 Nov 2022 15:34:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236135AbiKNPeR (ORCPT ); Mon, 14 Nov 2022 10:34:17 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56658 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236008AbiKNPeP (ORCPT ); Mon, 14 Nov 2022 10:34:15 -0500 Received: from smtp-out2.suse.de (smtp-out2.suse.de [IPv6:2001:67c:2178:6::1d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 38244AE63; Mon, 14 Nov 2022 07:34:14 -0800 (PST) Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out2.suse.de (Postfix) with ESMTP id 9C2321FFD1; Mon, 14 Nov 2022 15:34:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1668440052; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=iX0twiutIXQvyzjvENfNYeTzi5iV06fn6/uJ3rwwZHQ=; b=CSqUQJ08j5/qIt6kMB+TN0dttJya6Uhm0czVdp3AA47iPq4SLqKwE0jAXalRa4kxsrFQiv Ue+cwR7I2ZEkuCD6NoN7jvTBC/sog6Tt4IKCxLbydvrfyKmt2pclKFrhOQGYKiVjtT2JW2 rdKzXoU7xcaRXSO722vtMJPAQeuhPsQ= Received: from suse.cz (unknown [10.100.201.202]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by relay2.suse.de (Postfix) with ESMTPS id E91DB2C143; Mon, 14 Nov 2022 15:34:10 +0000 (UTC) Date: Mon, 14 Nov 2022 16:34:07 +0100 From: Petr Mladek To: Russell King Cc: Linus Walleij , Bartosz Golaszewski , Rob Herring , Lee Jones , Alyssa Rosenzweig , Andy Shevchenko , asahi@lists.linux.dev, devicetree@vger.kernel.org, Hector Martin , Jonathan Corbet , Krzysztof Kozlowski , linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-gpio@vger.kernel.org, Rasmus Villemoes , Sergey Senozhatsky , Steven Rostedt , Sven Peter Subject: Re: [PATCH v3 2/7] lib/vsprintf: Add support for generic FOURCCs by extending %p4cc Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On Tue 2022-11-08 16:33:22, Russell King wrote: > From: Hector Martin > > %p4cc is designed for DRM/V4L2 FOURCCs with their specific quirks, but > it's useful to be able to print generic 4-character codes formatted as > an integer. Extend it to add format specifiers for printing generic > 32-bit FOURCCs with various endian semantics: > > %p4ch Host-endian > %p4cl Little-endian > %p4cb Big-endian > %p4cr Reverse-endian > > The endianness determines how bytes are interpreted as a u32, and the > FOURCC is then always printed MSByte-first (this is the opposite of > V4L/DRM FOURCCs). This covers most practical cases, e.g. %p4cr would > allow printing LSByte-first FOURCCs stored in host endian order > (other than the hex form being in character order, not the integer > value). > > Signed-off-by: Hector Martin > Signed-off-by: Russell King (Oracle) Reviewed-by: Petr Mladek See one nit below. > --- a/lib/vsprintf.c > +++ b/lib/vsprintf.c > @@ -1762,27 +1762,50 @@ char *fourcc_string(char *buf, char *end, const u32 *fourcc, > char output[sizeof("0123 little-endian (0x01234567)")]; > char *p = output; > unsigned int i; > + bool pixel_fmt = false; > u32 orig, val; > > - if (fmt[1] != 'c' || fmt[2] != 'c') > + if (fmt[1] != 'c') > return error_string(buf, end, "(%p4?)", spec); > > if (check_pointer(&buf, end, fourcc, spec)) > return buf; > > orig = get_unaligned(fourcc); > - val = orig & ~BIT(31); > + switch (fmt[2]) { > + case 'h': > + val = orig; > + break; > + case 'r': > + val = orig = swab32(orig); I do not like much these multi assignments. I think that the result was not even defined in some older C standards. Though, I can't find it now. And even make W=3 does not warn about it. > + break; > + case 'l': > + val = orig = le32_to_cpu(orig); > + break; > + case 'b': > + val = orig = be32_to_cpu(orig); > + break; Best Regards, Petr