From patchwork Tue Nov 3 13:34:00 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sakari Ailus X-Patchwork-Id: 315056 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=-12.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT autolearn=unavailable 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 6E92EC388F9 for ; Tue, 3 Nov 2020 13:37:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1C10A22243 for ; Tue, 3 Nov 2020 13:37:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729260AbgKCNhh (ORCPT ); Tue, 3 Nov 2020 08:37:37 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39096 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729249AbgKCNhg (ORCPT ); Tue, 3 Nov 2020 08:37:36 -0500 Received: from hillosipuli.retiisi.eu (hillosipuli.retiisi.eu [IPv6:2a01:4f9:c010:4572::81:2]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 41301C0613D1; Tue, 3 Nov 2020 05:37:36 -0800 (PST) Received: from lanttu.localdomain (lanttu-e.localdomain [192.168.1.64]) by hillosipuli.retiisi.eu (Postfix) with ESMTP id 44839634C24; Tue, 3 Nov 2020 15:36:31 +0200 (EET) From: Sakari Ailus To: linux-kernel@vger.kernel.org Cc: linux-media@vger.kernel.org, Andy Shevchenko , Petr Mladek , Dave Stevenson , dri-devel@lists.freedesktop.org, hverkuil@xs4all.nl, laurent.pinchart@ideasonboard.com, mchehab@kernel.org, Sergey Senozhatsky , Steven Rostedt , Joe Perches , Jani Nikula , Rasmus Villemoes Subject: [PATCH v4 1/1] lib/vsprintf: Add support for printing V4L2 and DRM fourccs Date: Tue, 3 Nov 2020 15:34:00 +0200 Message-Id: <20201103133400.24805-1-sakari.ailus@linux.intel.com> X-Mailer: git-send-email 2.27.0 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org Add a printk modifier %p4cc (for pixel format) for printing V4L2 and DRM pixel formats denoted by fourccs. The fourcc encoding is the same for both so the same implementation can be used. Suggested-by: Mauro Carvalho Chehab Signed-off-by: Sakari Ailus --- Hi folks, I believe I've addressed comments from Rasmus, Joe and Andy --- variables that don't need to be negative have remained unsigned though. Thanks for the suggestions, I believe this is much cleaner than v3. since v3: - Remove use of WARN_ON, assume the code is correct instead. A side effect of this is the code is much easier to understand. - Check the modifier first before validating the buf pointer. - Use isascii() and isprint() functions to weed out non-printable characters. - Use hex_byte_pack() for printing 8-bit hexadecimal numbers. - Remove macros, and instead use plain strings. - Use strcpy() to copy the endianness string, and then strlen() to add its length. - Strip the MSB (endianness bit), then use the value as such. - Assign characters to the buffer and increment active pointer at the same time. - Drop __ from variable names. - Add example to documentation. Documentation/core-api/printk-formats.rst | 16 +++++++ lib/test_printf.c | 17 ++++++++ lib/vsprintf.c | 52 +++++++++++++++++++++++ 3 files changed, 85 insertions(+) diff --git a/Documentation/core-api/printk-formats.rst b/Documentation/core-api/printk-formats.rst index 6d26c5c6ac48..080262d2e030 100644 --- a/Documentation/core-api/printk-formats.rst +++ b/Documentation/core-api/printk-formats.rst @@ -565,6 +565,22 @@ For printing netdev_features_t. Passed by reference. +V4L2 and DRM FourCC code (pixel format) +--------------------------------------- + +:: + + %p4cc + +Print a FourCC code used by V4L2 or DRM, including format endianness and +its numerical value as hexadecimal. + +Passed by reference. + +Examples:: + + %p4cc BG12 little-endian (0x32314742) + Thanks ====== diff --git a/lib/test_printf.c b/lib/test_printf.c index 7ac87f18a10f..7fb042542660 100644 --- a/lib/test_printf.c +++ b/lib/test_printf.c @@ -649,6 +649,22 @@ static void __init fwnode_pointer(void) software_node_unregister(&softnodes[0]); } +static void __init fourcc_pointer(void) +{ + struct { + u32 code; + char *str; + } const try[] = { + { 0x20104646, "FF(10) little-endian (0x20104646)", }, + { 0xa0104646, "FF(10) big-endian (0xa0104646)", }, + { 0x10111213, "(13)(12)(11)(10) little-endian (0x10111213)", }, + }; + unsigned int i; + + for (i = 0; i < ARRAY_SIZE(try); i++) + test(try[i].str, "%p4cc", &try[i].code); +} + static void __init errptr(void) { @@ -694,6 +710,7 @@ test_pointer(void) flags(); errptr(); fwnode_pointer(); + fourcc_pointer(); } static void __init selftest(void) diff --git a/lib/vsprintf.c b/lib/vsprintf.c index 14c9a6af1b23..2be86b302c88 100644 --- a/lib/vsprintf.c +++ b/lib/vsprintf.c @@ -1733,6 +1733,55 @@ char *netdev_bits(char *buf, char *end, const void *addr, return special_hex_number(buf, end, num, size); } +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 (0x01234567)")]; + char *p = output; + unsigned int i; + u32 val; + + if (fmt[1] != 'c' || fmt[2] != 'c') + return error_string(output, end, "(%p4?)", spec); + + if (check_pointer(&buf, end, fourcc, spec)) + return buf; + + val = *fourcc & ~BIT(31); + + for (i = 0; i < sizeof(*fourcc); i++) { + unsigned char c = val >> (i * 8); + + /* Weed out spaces */ + if (c == ' ') + continue; + + /* Print non-control ASCII characters as-is */ + if (isascii(c) && isprint(c)) { + *p++ = c; + continue; + } + + *p++ = '('; + p = hex_byte_pack(p, c); + *p++ = ')'; + } + + strcpy(p, *fourcc & BIT(31) ? " big-endian" : " little-endian"); + p += strlen(p); + + *p++ = ' '; + *p++ = '('; + /* subtract parenthesis and the space from the size */ + p = special_hex_number(p, output + sizeof(output) - 2, *fourcc, + sizeof(u32)); + *p++ = ')'; + *p = '\0'; + + return string(buf, end, output, spec); +} + static noinline_for_stack char *address_val(char *buf, char *end, const void *addr, struct printf_spec spec, const char *fmt) @@ -2162,6 +2211,7 @@ char *fwnode_string(char *buf, char *end, struct fwnode_handle *fwnode, * correctness of the format string and va_list arguments. * - 'K' For a kernel pointer that should be hidden from unprivileged users * - 'NF' For a netdev_features_t + * - '4cc' V4L2 or DRM FourCC code, with endianness and raw numerical value. * - 'h[CDN]' For a variable-length buffer, it prints it as a hex string with * a certain separator (' ' by default): * C colon @@ -2259,6 +2309,8 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr, return restricted_pointer(buf, end, ptr, spec); case 'N': return netdev_bits(buf, end, ptr, spec, fmt); + case '4': + return fourcc_string(buf, end, ptr, spec, fmt); case 'a': return address_val(buf, end, ptr, spec, fmt); case 'd':