From patchwork Wed Jul 21 17:55:21 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Sean Paul X-Patchwork-Id: 12391843 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=-16.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham 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 07FAEC636C9 for ; Wed, 21 Jul 2021 17:56:34 +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 D0BB06113C for ; Wed, 21 Jul 2021 17:56:33 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D0BB06113C Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=poorly.run 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 63E4A6E991; Wed, 21 Jul 2021 17:56:33 +0000 (UTC) Received: from mail-qt1-x82e.google.com (mail-qt1-x82e.google.com [IPv6:2607:f8b0:4864:20::82e]) by gabe.freedesktop.org (Postfix) with ESMTPS id 991A36E991 for ; Wed, 21 Jul 2021 17:56:32 +0000 (UTC) Received: by mail-qt1-x82e.google.com with SMTP id d15so2430650qte.13 for ; Wed, 21 Jul 2021 10:56:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=poorly.run; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=CH2kPjmK/HYIHIFGLb86BP+Lyj1IMPrr9Abe3xfbcVc=; b=PfAhfxAWbhF3Qih/yiBiz6VRFB6roXU1H42ZWE0sXg4SlsWfzH42y99iqM6Z1FKY3E n89th2CTipVKay6r5KCOF/42VaaHu3vZlLae201JvvntSC1E7ZfoyujRLaLSl7vsn5iF PI+uKkdNmmAHkrRl23rmypZvaU2SgJItwQHqTVeDE83k4/1wAwlOijRMfM69ahUOc9ql SVjtKLcslSagtxg2xsPoSn6F2+uRp0zaCWSoEjUV+xR7DxZgGqoSSYuXPk3PmjWO7scZ kTIrryu0vJIvZeqx5PR0absr5coUStWI9W2xpKbHR0mRDD4EMT17St9IjcFs7jrnFGUy l/aw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=CH2kPjmK/HYIHIFGLb86BP+Lyj1IMPrr9Abe3xfbcVc=; b=FJRo/9CG7iJpCl9Qq2reTpshiBsVxaf8OItbudCV1tQj/CWmK8Od1WWfQWnnX7wMiK PdAjvK4xIx6KNB+NaDGfqnqoKSfxzqozkSY/TM+BD++w4Fg6JdMNqdVljmBihyaqTYNl vZ+htrEQH/dPvHGrzKKEd0ml+IrI2nXTW19WmQITM7EVKcz5LDHPwDcPlBD0pr21ysfU lwJpNdxJ4yPs0XxFn9NbiLlSVZv3y8jygINBo+SdrLgUVegzvKAzK28++rSqvtgZFNOQ CpcOkDlWDPrsm4sJDFMf5dQcjLG8QWSklVYLBNiUOXKfl7SAKR0Ml8Z/P6aY38XulQ4n 0f0w== X-Gm-Message-State: AOAM530ibEwLnCBShEdcz79u1d+Y37n6w4pom+4lg8lMnZ+oezdmFmAB DDyLXiN8tSek/Y68QRXv8Q1dZjnH+sSzNg== X-Google-Smtp-Source: ABdhPJzBZMRT3l18XCw+swJ/gW66HlI1EvzoBwcldy09Gfe1JQ+5e1RwMD4Iz0EEsF6Wc6Z43YLeSA== X-Received: by 2002:a05:622a:50:: with SMTP id y16mr12210546qtw.322.1626890191672; Wed, 21 Jul 2021 10:56:31 -0700 (PDT) Received: from localhost ([167.100.64.199]) by smtp.gmail.com with ESMTPSA id r4sm9583651qtc.66.2021.07.21.10.56.31 (version=TLS1_2 cipher=ECDHE-ECDSA-CHACHA20-POLY1305 bits=256/256); Wed, 21 Jul 2021 10:56:31 -0700 (PDT) From: Sean Paul To: dri-devel@lists.freedesktop.org, ppaalanen@gmail.com, maarten.lankhorst@linux.intel.com, tzimmermann@suse.de, airlied@linux.ie, daniel.vetter@ffwll.ch Subject: [RESEND PATCH v6 14/14] drm/print: Add tracefs support to the drm logging helpers Date: Wed, 21 Jul 2021 13:55:21 -0400 Message-Id: <20210721175526.22020-15-sean@poorly.run> X-Mailer: git-send-email 2.31.0 In-Reply-To: <20210721175526.22020-1-sean@poorly.run> References: <20210721175526.22020-1-sean@poorly.run> MIME-Version: 1.0 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: Pekka Paalanen , kernel test robot , Jonathan Corbet , linux-doc@vger.kernel.org, Steven Rostedt , Chris Wilson , Sean Paul Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" From: Sean Paul This patch adds a new module parameter called drm.trace which accepts the same mask as drm.debug. When a debug category is enabled, log messages will be put in a new tracefs instance called drm for consumption. Using the new tracefs instance will allow distros to enable drm logging in production without impacting performance or spamming the system logs. Cc: Daniel Vetter Cc: David Airlie Cc: Jani Nikula Cc: Joonas Lahtinen Cc: Pekka Paalanen Cc: Rob Clark Cc: Steven Rostedt Cc: Thomas Zimmermann Cc: Ville Syrjälä Cc: Chris Wilson Cc: Steven Rostedt Reported-by: kernel test robot # warning reported in v6 Acked-by: Pekka Paalanen Signed-off-by: Sean Paul Link: https://patchwork.freedesktop.org/patch/msgid/20191010204823.195540-1-sean@poorly.run #v1 Link: https://lists.freedesktop.org/archives/dri-devel/2019-November/243230.html #v2 Link: https://patchwork.freedesktop.org/patch/msgid/20191212203301.142437-1-sean@poorly.run #v3 Link: https://patchwork.freedesktop.org/patch/msgid/20200114172155.215463-1-sean@poorly.run #v4 Link: https://patchwork.freedesktop.org/patch/msgid/20200608210505.48519-14-sean@poorly.run #v5 Link: https://patchwork.freedesktop.org/patch/msgid/20200818210510.49730-15-sean@poorly.run #v6 Changes in v5: -Re-write to use trace_array and the tracefs instance support Changes in v6: -Use the new trace_array_init_printk() to initialize global trace buffers Changes in v6.5: -Fix kernel test robot warning -Add a trace printf in __drm_err Reviewed-by: Rodrigo Siqueira --- Documentation/gpu/drm-uapi.rst | 6 + drivers/gpu/drm/drm_drv.c | 3 + drivers/gpu/drm/drm_print.c | 223 ++++++++++++++++++++++++++++----- include/drm/drm_print.h | 63 ++++++++-- 4 files changed, 255 insertions(+), 40 deletions(-) diff --git a/Documentation/gpu/drm-uapi.rst b/Documentation/gpu/drm-uapi.rst index 7e51dd40bf6e..ce1ea39fb4b9 100644 --- a/Documentation/gpu/drm-uapi.rst +++ b/Documentation/gpu/drm-uapi.rst @@ -424,6 +424,12 @@ Debugfs Support .. kernel-doc:: drivers/gpu/drm/drm_debugfs.c :export: +DRM Tracing +--------------- + +.. kernel-doc:: drivers/gpu/drm/drm_print.c + :doc: DRM Tracing + Sysfs Support ============= diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c index 8804ec7d3215..71dc0b161b51 100644 --- a/drivers/gpu/drm/drm_drv.c +++ b/drivers/gpu/drm/drm_drv.c @@ -1034,12 +1034,15 @@ static void drm_core_exit(void) drm_sysfs_destroy(); idr_destroy(&drm_minors_idr); drm_connector_ida_destroy(); + drm_trace_cleanup(); } static int __init drm_core_init(void) { int ret; + drm_trace_init(); + drm_connector_ida_init(); idr_init(&drm_minors_idr); drm_memcpy_init_early(); diff --git a/drivers/gpu/drm/drm_print.c b/drivers/gpu/drm/drm_print.c index 4d984a01b3a3..64d9a724c2df 100644 --- a/drivers/gpu/drm/drm_print.c +++ b/drivers/gpu/drm/drm_print.c @@ -31,6 +31,7 @@ #include #include #include +#include #include #include @@ -43,17 +44,34 @@ unsigned int __drm_debug_syslog; EXPORT_SYMBOL(__drm_debug_syslog); -MODULE_PARM_DESC(debug, "Enable debug output, where each bit enables a debug category.\n" -"\t\tBit 0 (0x01) will enable CORE messages (drm core code)\n" -"\t\tBit 1 (0x02) will enable DRIVER messages (drm controller code)\n" -"\t\tBit 2 (0x04) will enable KMS messages (modesetting code)\n" -"\t\tBit 3 (0x08) will enable PRIME messages (prime code)\n" -"\t\tBit 4 (0x10) will enable ATOMIC messages (atomic code)\n" -"\t\tBit 5 (0x20) will enable VBL messages (vblank code)\n" -"\t\tBit 7 (0x80) will enable LEASE messages (leasing code)\n" -"\t\tBit 8 (0x100) will enable DP messages (displayport code)"); +/* + * __drm_debug_trace: Enable debug output in drm tracing instance. + * Bitmask of DRM_UT_x. See include/drm/drm_print.h for details. + */ +unsigned int __drm_debug_trace; +EXPORT_SYMBOL(__drm_debug_trace); + +#define DEBUG_PARM_DESC(dst) \ +"Enable debug output to " dst ", where each bit enables a debug category.\n" \ +"\t\tBit 0 (0x01) will enable CORE messages (drm core code)\n" \ +"\t\tBit 1 (0x02) will enable DRIVER messages (drm controller code)\n" \ +"\t\tBit 2 (0x04) will enable KMS messages (modesetting code)\n" \ +"\t\tBit 3 (0x08) will enable PRIME messages (prime code)\n" \ +"\t\tBit 4 (0x10) will enable ATOMIC messages (atomic code)\n" \ +"\t\tBit 5 (0x20) will enable VBL messages (vblank code)\n" \ +"\t\tBit 7 (0x80) will enable LEASE messages (leasing code)\n" \ +"\t\tBit 8 (0x100) will enable DP messages (displayport code)" + +MODULE_PARM_DESC(debug, DEBUG_PARM_DESC("syslog")); module_param_named(debug, __drm_debug_syslog, int, 0600); +MODULE_PARM_DESC(trace, DEBUG_PARM_DESC("tracefs")); +module_param_named(trace, __drm_debug_trace, int, 0600); + +#ifdef CONFIG_TRACING +struct trace_array *trace_arr; +#endif + void __drm_puts_coredump(struct drm_printer *p, const char *str) { struct drm_print_iterator *iterator = p->arg; @@ -166,6 +184,20 @@ void __drm_printfn_debug_syslog(struct drm_printer *p, struct va_format *vaf) } EXPORT_SYMBOL(__drm_printfn_debug_syslog); +void __drm_printfn_trace(struct drm_printer *p, struct va_format *vaf) +{ + drm_trace_printf("%s %pV", p->prefix, vaf); +} +EXPORT_SYMBOL(__drm_printfn_trace); + +void __drm_printfn_debug_syslog_and_trace(struct drm_printer *p, + struct va_format *vaf) +{ + pr_debug("%s %pV", p->prefix, vaf); + drm_trace_printf("%s %pV", p->prefix, vaf); +} +EXPORT_SYMBOL(__drm_printfn_debug_syslog_and_trace); + void __drm_printfn_err(struct drm_printer *p, struct va_format *vaf) { pr_err("*ERROR* %s %pV", p->prefix, vaf); @@ -246,6 +278,14 @@ void drm_dev_printk(const struct device *dev, const char *level, struct va_format vaf; va_list args; + va_start(args, format); + vaf.fmt = format; + vaf.va = &args; + drm_trace_printf("%s%s[" DRM_NAME ":%ps] %pV", + dev ? dev_name(dev) : "",dev ? " " : "", + __builtin_return_address(0), &vaf); + va_end(args); + va_start(args, format); vaf.fmt = format; vaf.va = &args; @@ -267,21 +307,30 @@ void drm_dev_dbg(const struct device *dev, enum drm_debug_category category, struct va_format vaf; va_list args; - if (!drm_debug_enabled(category)) - return; + if (drm_debug_syslog_enabled(category)) { + va_start(args, format); + vaf.fmt = format; + vaf.va = &args; - va_start(args, format); - vaf.fmt = format; - vaf.va = &args; + if (dev) + dev_printk(KERN_DEBUG, dev, "[" DRM_NAME ":%ps] %pV", + __builtin_return_address(0), &vaf); + else + printk(KERN_DEBUG "[" DRM_NAME ":%ps] %pV", + __builtin_return_address(0), &vaf); - if (dev) - dev_printk(KERN_DEBUG, dev, "[" DRM_NAME ":%ps] %pV", - __builtin_return_address(0), &vaf); - else - printk(KERN_DEBUG "[" DRM_NAME ":%ps] %pV", - __builtin_return_address(0), &vaf); + va_end(args); + } - va_end(args); + if (drm_debug_trace_enabled(category)) { + va_start(args, format); + vaf.fmt = format; + vaf.va = &args; + drm_trace_printf("%s%s[" DRM_NAME ":%ps] %pV", + dev ? dev_name(dev) : "", dev ? " " : "", + __builtin_return_address(0), &vaf); + va_end(args); + } } EXPORT_SYMBOL(drm_dev_dbg); @@ -290,17 +339,25 @@ void __drm_dbg(enum drm_debug_category category, const char *format, ...) struct va_format vaf; va_list args; - if (!drm_debug_enabled(category)) - return; + if (drm_debug_syslog_enabled(category)) { + va_start(args, format); + vaf.fmt = format; + vaf.va = &args; - va_start(args, format); - vaf.fmt = format; - vaf.va = &args; + printk(KERN_DEBUG "[" DRM_NAME ":%ps] %pV", + __builtin_return_address(0), &vaf); - printk(KERN_DEBUG "[" DRM_NAME ":%ps] %pV", - __builtin_return_address(0), &vaf); + va_end(args); + } - va_end(args); + if (drm_debug_trace_enabled(category)) { + va_start(args, format); + vaf.fmt = format; + vaf.va = &args; + drm_trace_printf("[" DRM_NAME ":%ps] %pV", + __builtin_return_address(0), &vaf); + va_end(args); + } } EXPORT_SYMBOL(__drm_dbg); @@ -317,6 +374,13 @@ void __drm_err(const char *format, ...) __builtin_return_address(0), &vaf); va_end(args); + + va_start(args, format); + vaf.fmt = format; + vaf.va = &args; + drm_trace_printf("[" DRM_NAME ":%ps] *ERROR* %pV", + __builtin_return_address(0), &vaf); + va_end(args); } EXPORT_SYMBOL(__drm_err); @@ -347,3 +411,104 @@ void drm_print_regset32(struct drm_printer *p, struct debugfs_regset32 *regset) } } EXPORT_SYMBOL(drm_print_regset32); + + +/** + * DOC: DRM Tracing + * + * *tl;dr* DRM tracing is a lightweight alternative to traditional DRM debug + * logging. + * + * While DRM logging is quite convenient when reproducing a specific issue, it + * doesn't help when something goes wrong unexpectedly. There are a couple + * reasons why one does not want to enable DRM logging at all times: + * + * 1. We don't want to overwhelm syslog with drm spam, others have to use it too + * 2. Console logging is slow + * + * DRM tracing aims to solve both these problems. + * + * To use DRM tracing, set the drm.trace module parameter (via cmdline or sysfs) + * to a DRM debug category mask (this is a bitmask of &drm_debug_category + * values): + * :: + * + * eg: echo 0x106 > /sys/module/drm/parameters/trace + * + * Once active, all log messages in the specified categories will be written to + * the DRM trace. Once at capacity, the trace will overwrite old messages with + * new ones. At any point, one can read the trace file to extract the previous N + * DRM messages: + * :: + * + * eg: cat /sys/kernel/tracing/instances/drm/trace + * + * Considerations + * ************** + * The trace is subsystem wide, so if you have multiple devices active, they + * will be adding logs to the same trace. + * + * The contents of the DRM Trace are **not** considered UABI. **DO NOT depend on + * the values of these traces in your userspace.** These traces are intended for + * entertainment purposes only. The contents of these logs carry no warranty, + * expressed or implied. + */ + + +#ifdef CONFIG_TRACING + +/** + * drm_trace_init - initializes the drm trace array + * + * This function fetches (or creates) the drm trace array. This should be called + * once on drm subsystem creation and matched with drm_trace_cleanup(). + */ +void drm_trace_init(void) +{ + int ret; + + trace_arr = trace_array_get_by_name("drm"); + if (!trace_arr) + return; + + ret = trace_array_init_printk(trace_arr); + if (ret) + drm_trace_cleanup(); +} +EXPORT_SYMBOL(drm_trace_init); + +/** + * drm_trace_printf - adds an entry to the drm tracefs instance + * @format: printf format of the message to add to the trace + * + * This function adds a new entry in the drm tracefs instance + */ +void drm_trace_printf(const char *format, ...) +{ + struct va_format vaf; + va_list args; + + va_start(args, format); + vaf.fmt = format; + vaf.va = &args; + trace_array_printk(trace_arr, _THIS_IP_, "%pV", &vaf); + va_end(args); +} + +/** + * drm_trace_cleanup - destroys the drm trace array + * + * This function destroys the drm trace array created with drm_trace_init. This + * should be called once on drm subsystem close and matched with + * drm_trace_init(). + */ +void drm_trace_cleanup(void) +{ + if (trace_arr) { + trace_array_put(trace_arr); + trace_array_destroy(trace_arr); + trace_arr = NULL; + } +} +EXPORT_SYMBOL(drm_trace_cleanup); +#endif \ No newline at end of file diff --git a/include/drm/drm_print.h b/include/drm/drm_print.h index af31beeb82a1..4609a2f4a425 100644 --- a/include/drm/drm_print.h +++ b/include/drm/drm_print.h @@ -36,12 +36,13 @@ /* Do *not* use outside of drm_print.[ch]! */ extern unsigned int __drm_debug_syslog; +extern unsigned int __drm_debug_trace; /** * DOC: print * * A simple wrapper for dev_printk(), seq_printf(), etc. Allows same - * debug code to be used for both debugfs and printk logging. + * debug code to be used for debugfs, printk and tracefs logging. * * For example:: * @@ -86,6 +87,9 @@ void __drm_printfn_seq_file(struct drm_printer *p, struct va_format *vaf); void __drm_puts_seq_file(struct drm_printer *p, const char *str); void __drm_printfn_info(struct drm_printer *p, struct va_format *vaf); void __drm_printfn_debug_syslog(struct drm_printer *p, struct va_format *vaf); +void __drm_printfn_trace(struct drm_printer *p, struct va_format *vaf); +void __drm_printfn_debug_syslog_and_trace(struct drm_printer *p, + struct va_format *vaf); void __drm_printfn_err(struct drm_printer *p, struct va_format *vaf); void __drm_printfn_noop(struct drm_printer *p, struct va_format *vaf); @@ -219,7 +223,8 @@ static inline struct drm_printer drm_info_printer(struct device *dev) } /** - * drm_debug_printer - construct a &drm_printer that outputs to pr_debug() + * drm_debug_printer - construct a &drm_printer that outputs to pr_debug() and + * drm tracefs * @prefix: debug output prefix * * RETURNS: @@ -228,7 +233,7 @@ static inline struct drm_printer drm_info_printer(struct device *dev) static inline struct drm_printer drm_debug_printer(const char *prefix) { struct drm_printer p = { - .printfn = __drm_printfn_debug_syslog, + .printfn = __drm_printfn_debug_syslog_and_trace, .prefix = prefix }; return p; @@ -254,14 +259,14 @@ static inline struct drm_printer drm_err_printer(const char *prefix) * enum drm_debug_category - The DRM debug categories * * Each of the DRM debug logging macros use a specific category, and the logging - * is filtered by the drm.debug module parameter. This enum specifies the values - * for the interface. + * is filtered by the drm.debug and drm.trace module parameters. This enum + * specifies the values for the interface. * * Each DRM_DEBUG_ macro logs to DRM_UT_ category, except * DRM_DEBUG() logs to DRM_UT_CORE. * - * Enabling verbose debug messages is done through the drm.debug parameter, each - * category being enabled by a bit: + * Enabling verbose debug messages is done through the drm.debug and drm.trace + * parameters, each category being enabled by a bit: * * - drm.debug=0x1 will enable CORE messages * - drm.debug=0x2 will enable DRIVER messages @@ -270,10 +275,14 @@ static inline struct drm_printer drm_err_printer(const char *prefix) * - drm.debug=0x1ff will enable all messages * * An interesting feature is that it's possible to enable verbose logging at - * run-time by echoing the debug value in its sysfs node:: + * run-time by echoing the debug category value in its sysfs node:: * + * # For syslog logging: * # echo 0xf > /sys/module/drm/parameters/debug * + * # For tracefs logging: + * # echo 0xf > /sys/module/drm/parameters/trace + * */ enum drm_debug_category { /** @@ -325,14 +334,20 @@ static inline bool drm_debug_syslog_enabled(enum drm_debug_category category) return unlikely(__drm_debug_syslog & category); } +static inline bool drm_debug_trace_enabled(enum drm_debug_category category) +{ + return unlikely(__drm_debug_trace & category); +} + static inline bool drm_debug_enabled(enum drm_debug_category category) { - return drm_debug_syslog_enabled(category); + return drm_debug_syslog_enabled(category) || + drm_debug_trace_enabled(category); } /** * drm_debug_category_printer - construct a &drm_printer that outputs to - * pr_debug() if enabled for the given category. + * pr_debug() and/or the drm tracefs instance if enabled for the given category. * @category: the DRM_UT_* message category this message belongs to * @prefix: trace output prefix * @@ -347,8 +362,13 @@ drm_debug_category_printer(enum drm_debug_category category, .prefix = prefix }; - if (drm_debug_syslog_enabled(category)) { + if (drm_debug_syslog_enabled(category) && + drm_debug_trace_enabled(category)) { + p.printfn = __drm_printfn_debug_syslog_and_trace; + } else if (drm_debug_syslog_enabled(category)) { p.printfn = __drm_printfn_debug_syslog; + } else if (drm_debug_trace_enabled(category)) { + p.printfn = __drm_printfn_trace; } else { WARN(1, "Debug category %d is inactive.", category); p.printfn = __drm_printfn_noop; @@ -357,6 +377,27 @@ drm_debug_category_printer(enum drm_debug_category category, return p; } + +#ifdef CONFIG_TRACING +void drm_trace_init(void); +__printf(1, 2) +void drm_trace_printf(const char *format, ...); +void drm_trace_cleanup(void); +#else +static inline void drm_trace_init(void) +{ +} + +__printf(1, 2) +static inline void drm_trace_printf(const char *format, ...) +{ +} + +static inline void drm_trace_cleanup(void) +{ +} +#endif + /* * struct device based logging *