[RFC PATCH 0/4] use DYNAMIC_DEBUG in drm/print

[RFC PATCH 0/4] use DYNAMIC_DEBUG in drm/print

[Jim Cromie]

hi everyone,

this patchset reworks the drm.debug controlled debug categories,
and remaps them to use dynamic_debug_exec_queries().

To do this "smoothly", DRM_UT_* is converted from an enum to a
class-prefix string, which is prepended## to the real format string.
This lets us use:

 $> echo module drm\* format ^drm:kms: +p > /proc/dynamic_debug/control

3rd patch fixes a conflict while rebasing to rc3. I kept the fixup
separate for more visibility.

commit c5261e93758a6b36f4292403027af383ec9da129
Author: Lyude Paul <lyude@redhat.com>
Date:   Fri Mar 26 16:37:54 2021 -0400

    drm/print: Fixup DRM_DEBUG_KMS_RATELIMITED()
    
    Since we're about to move drm_dp_helper.c over to drm_dbg_*(), we'll want
    to make sure that we can also add ratelimited versions of these macros in
    order to retain some of the previous debugging output behavior we had.

I can see I havent been paying attention.
Are plans laid out where I can catch up quickly ?

Separately, but related, I have an RFC patchset on LKML to reduce
DYNAMIC_DEBUG's memory overhead.  Patch 34 hints that rate-limiting
can be done dynamically, on demand, for any prdbg known to
dynamic_debug.

https://lore.kernel.org/lkml/20210529200029.205306-1-jim.cromie@gmail.com/T/#ma5052696fe9171649b93b3e1f482de90314a9b61

Jim Cromie (4):
  drm: fixup comment spelling
  drm: RFC add choice to use dynamic debug in drm-debug
  drm: fixup DRM_DEBUG_KMS_RATELIMITED merge punt
  i915: map gvt pr_debug categories to bits in parameters/debug_gvt

 drivers/gpu/drm/Kconfig            |  13 ++++
 drivers/gpu/drm/drm_print.c        |  75 ++++++++++++++++++-
 drivers/gpu/drm/i915/gvt/Makefile  |   4 +
 drivers/gpu/drm/i915/i915_params.c |  76 +++++++++++++++++++
 include/drm/drm_print.h            | 116 ++++++++++++++++++++---------
 5 files changed, 243 insertions(+), 41 deletions(-)

-- 
2.31.1

[RFC PATCH 1/4] drm: fixup comment spelling

[Jim Cromie]

s/prink/printk/ - no functional changes

Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
 include/drm/drm_print.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/drm/drm_print.h b/include/drm/drm_print.h
index a3c58c941bdc..9377a17d74f1 100644
--- a/include/drm/drm_print.h
+++ b/include/drm/drm_print.h
@@ -327,7 +327,7 @@ static inline bool drm_debug_enabled(enum drm_debug_category category)
 /*
  * struct device based logging
  *
- * Prefer drm_device based logging over device or prink based logging.
+ * Prefer drm_device based logging over device or printk based logging.
  */
 
 __printf(3, 4)
-- 
2.31.1

[RFC PATCH 2/4] drm: RFC add choice to use dynamic debug in drm-debug

[Jim Cromie]

drm's debug system uses distinct categories of debug messages, mapped
to bits in drm.debug.  Currently, code does a lot of unlikely bit-mask
checks on drm.debug (in drm_debug_enabled), we can use dynamic debug
instead, and get all that jump_label goodness.

RFC: dynamic debug has no concept of category, but we can do without
one if we can prepend a class-prefix to each printk format.  Then we
can use "format ^prefix" to select the whole category with one query.
This is a log-facing and user visible change, but it seems unlikely to
cause trouble for log watchers; they're not relying on the absence of
class prefix strings.

This conversion yields ~2100 new callsites on my i7 laptop:

  dyndbg: 195 debug prints in module drm_kms_helper
  dyndbg: 298 debug prints in module drm
  dyndbg: 1630 debug prints in module i915

CONFIG_DRM_USE_DYNAMIC_DEBUG enables this, and is available if its
dependencies are enabled.

The indirection/switchover has a few parts:

1 a new callback on drm.debug which calls dynamic_debug_exec_queries
  to map those bits to specific query/commands
  dynamic_debug_exec_queries("format ^drm:kms: +p", "drm*");

2 a "converted" or "classy" DRM_UT_* map
  similar to DRM_UT_* ( symbol => bit-mask )
  named it  cDRM_UT_* ( symbol => format-class-prefix-string )

  cDRM_UT_* is either ( CONFIG_DRM_USE_DYNAMIC_DEBUG )
  legacy: cDRM_UT_* <-- DRM_UT_*
  enabled:
  +#define cDRM_UT_KMS    "drm:kms: "
  +#define cDRM_UT_PRIME  "drm:prime: "
  +#define cDRM_UT_ATOMIC "drm:atomic: "

  these are similar to "gvt: cmd:" in i915/gvt
  and effectively a replacement for DRM_NAME
  please bikeshed on keys, values. latter are log-facing.

3 drm_dev_dbg & drm_debug are renamed (prefixed with '_')
  old names are now macros, which are ifdefd
  legacy:  -> to renamed fn
  enabled: -> dev_dbg & pr_debug, after prepending prefix to format.

4 names in (2) are called from DRM_DEBUG_<Category> and drm_dbg_<Category>.
  all these get "converted" to use cDRM_UT_*, to get right token type.

RFC: for dynamic debug, category is a source-facing addition;
something like pr_debug_cat(cat, ...) would do it, iff cat is a
compile-time const.  Note that cat isn't needed in the printing, it
would be saved into a new field in struct _ddebug, and used only for
callsite selection, activation and control.

NOTE: conflict at KMS_RATELIMITED. I punted on proper resolution.
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
 drivers/gpu/drm/Kconfig     | 13 +++++
 drivers/gpu/drm/drm_print.c | 75 +++++++++++++++++++++++++++--
 include/drm/drm_print.h     | 95 +++++++++++++++++++++++++++----------
 3 files changed, 155 insertions(+), 28 deletions(-)

diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
index 3c16bd1afd87..0f9356417f7d 100644
--- a/drivers/gpu/drm/Kconfig
+++ b/drivers/gpu/drm/Kconfig
@@ -57,6 +57,19 @@ config DRM_DEBUG_MM
 
 	  If in doubt, say "N".
 
+config DRM_USE_DYNAMIC_DEBUG
+	bool "use dynamic debug to implement drm.debug"
+	default n
+	depends on DRM
+	depends on DYNAMIC_DEBUG || DYNAMIC_DEBUG_CORE
+	depends on JUMP_LABEL
+	help
+	  The drm debug category facility does a lot of unlikely bit-field
+	  tests at runtime; while cheap individually, the cost accumulates.
+	  This option uses dynamic debug facility (if configured and
+	  using jump_label) to avoid those runtime checks, patching
+	  the kernel when those debugs are desired.
+
 config DRM_DEBUG_SELFTEST
 	tristate "kselftests for DRM"
 	depends on DRM
diff --git a/drivers/gpu/drm/drm_print.c b/drivers/gpu/drm/drm_print.c
index 111b932cf2a9..e2acdfc7088b 100644
--- a/drivers/gpu/drm/drm_print.c
+++ b/drivers/gpu/drm/drm_print.c
@@ -52,8 +52,75 @@ MODULE_PARM_DESC(debug, "Enable debug output, where each bit enables a debug cat
 "\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)");
+
+#ifndef CONFIG_DRM_USE_DYNAMIC_DEBUG
 module_param_named(debug, __drm_debug, int, 0600);
 
+#else
+static char *format_class_prefixes[] = {
+	cDRM_UT_CORE,
+	cDRM_UT_DRIVER,
+	cDRM_UT_KMS,
+	cDRM_UT_PRIME,
+	cDRM_UT_ATOMIC,
+	cDRM_UT_VBL,
+	cDRM_UT_STATE,
+	cDRM_UT_LEASE,
+	cDRM_UT_DP,
+	cDRM_UT_DRMRES
+};
+
+#define OUR_QUERY_SIZE 64 /* > strlen "format '^%s' %cp" + longest prefix */
+
+static int param_set_dyndbg(const char *instr, const struct kernel_param *kp)
+{
+	unsigned int val;
+	unsigned long changes, result;
+	int rc, chgct = 0, totct = 0, bitpos;
+	char query[OUR_QUERY_SIZE];
+
+	rc = kstrtouint(instr, 0, &val);
+	if (rc) {
+		pr_err("%s: failed\n", __func__);
+		return -EINVAL;
+	}
+	result = val;
+	changes = result ^ __drm_debug;
+
+	pr_debug("changes:0x%lx from result:0x%lx\n", changes, result);
+
+	for_each_set_bit(bitpos, &changes, ARRAY_SIZE(format_class_prefixes)) {
+
+		sprintf(query, "format '^%s' %cp", format_class_prefixes[bitpos],
+			test_bit(bitpos, &result) ? '+' : '-');
+
+		chgct = dynamic_debug_exec_queries(query, "drm*");
+		if (chgct < 0) {
+			pr_err("%s: exec err:%d on: %s\n", __func__, chgct, query);
+			continue;
+		}
+		pr_debug("change ct:%d on %s\n", chgct, query);
+		totct += chgct;
+	}
+	pr_debug("total changes: %d\n", totct);
+	__drm_debug = result;
+	return 0;
+}
+
+static int param_get_dyndbg(char *buffer, const struct kernel_param *kp)
+{
+	pr_debug("debug-val:0x%x %u\n", __drm_debug, *((unsigned int *)kp->arg));
+	return scnprintf(buffer, PAGE_SIZE, "%u\n",
+			 *((unsigned int *)kp->arg));
+}
+static const struct kernel_param_ops param_ops_debug = {
+	.set = param_set_dyndbg,
+	.get = param_get_dyndbg,
+};
+module_param_cb(debug, &param_ops_debug, &__drm_debug, 0644);
+
+#endif /* CONFIG_DRM_USE_DYNAMIC_DEBUG */
+
 void __drm_puts_coredump(struct drm_printer *p, const char *str)
 {
 	struct drm_print_iterator *iterator = p->arg;
@@ -256,7 +323,7 @@ void drm_dev_printk(const struct device *dev, const char *level,
 }
 EXPORT_SYMBOL(drm_dev_printk);
 
-void drm_dev_dbg(const struct device *dev, enum drm_debug_category category,
+void _drm_dev_dbg(const struct device *dev, enum drm_debug_category category,
 		 const char *format, ...)
 {
 	struct va_format vaf;
@@ -278,9 +345,9 @@ void drm_dev_dbg(const struct device *dev, enum drm_debug_category category,
 
 	va_end(args);
 }
-EXPORT_SYMBOL(drm_dev_dbg);
+EXPORT_SYMBOL(_drm_dev_dbg);
 
-void __drm_dbg(enum drm_debug_category category, const char *format, ...)
+void ___drm_dbg(enum drm_debug_category category, const char *format, ...)
 {
 	struct va_format vaf;
 	va_list args;
@@ -297,7 +364,7 @@ void __drm_dbg(enum drm_debug_category category, const char *format, ...)
 
 	va_end(args);
 }
-EXPORT_SYMBOL(__drm_dbg);
+EXPORT_SYMBOL(___drm_dbg);
 
 void __drm_err(const char *format, ...)
 {
diff --git a/include/drm/drm_print.h b/include/drm/drm_print.h
index 9377a17d74f1..616fe5e83b50 100644
--- a/include/drm/drm_print.h
+++ b/include/drm/drm_print.h
@@ -31,6 +31,7 @@
 #include <linux/seq_file.h>
 #include <linux/device.h>
 #include <linux/debugfs.h>
+#include <linux/dynamic_debug.h>
 
 #include <drm/drm.h>
 
@@ -319,6 +320,51 @@ enum drm_debug_category {
 	DRM_UT_DRMRES		= 0x200,
 };
 
+#if !defined(CONFIG_DRM_USE_DYNAMIC_DEBUG)
+
+/* Use legacy drm-debug functions, and drm_debug_enabled().
+ * For cDRM_UT_* (converted category), identity map to DRM_UT_*
+ */
+#define __drm_dbg(cls, fmt, ...)			\
+	___drm_dbg(cls, fmt, ##__VA_ARGS__)
+#define drm_dev_dbg(dev, cls, fmt, ...)			\
+	_drm_dev_dbg(dev, cls, fmt, ##__VA_ARGS__)
+
+#define cDRM_UT_CORE	DRM_UT_CORE
+#define cDRM_UT_DRIVER	DRM_UT_DRIVER
+#define cDRM_UT_KMS	DRM_UT_KMS
+#define cDRM_UT_PRIME	DRM_UT_PRIME
+#define cDRM_UT_ATOMIC	DRM_UT_ATOMIC
+#define cDRM_UT_VBL	DRM_UT_VBL
+#define cDRM_UT_STATE	DRM_UT_STATE
+#define cDRM_UT_LEASE	DRM_UT_LEASE
+#define cDRM_UT_DP	DRM_UT_DP
+#define cDRM_UT_DRMRES	DRM_UT_DRMRES
+
+#else /* !CONFIG_DRM_USE_DYNAMIC_DEBUG */
+
+/* use dynamic_debug to avoid drm_debug_enabled().
+ * dyndbg has no category, so we prefix the format with a "class"
+ * string; cDRM_UT_* maps to those class strings
+ */
+#define __drm_dbg(cls, fmt, ...)		\
+	pr_debug(cls # fmt, ##__VA_ARGS__)
+#define drm_dev_dbg(dev, cls, fmt, ...)		\
+	dev_dbg(dev, cls fmt, ##__VA_ARGS__)
+
+#define cDRM_UT_CORE	"drm:core: "
+#define cDRM_UT_DRIVER	"drm:drvr: "
+#define cDRM_UT_KMS	"drm:kms: "
+#define cDRM_UT_PRIME	"drm:prime: "
+#define cDRM_UT_ATOMIC	"drm:atomic: "
+#define cDRM_UT_VBL	"drm:vbl: "
+#define cDRM_UT_STATE	"drm:state: "
+#define cDRM_UT_LEASE	"drm:lease: "
+#define cDRM_UT_DP	"drm:dp: "
+#define cDRM_UT_DRMRES	"drm:res "
+
+#endif /* !CONFIG_DRM_USE_DYNAMIC_DEBUG */
+
 static inline bool drm_debug_enabled(enum drm_debug_category category)
 {
 	return unlikely(__drm_debug & category);
@@ -334,7 +380,7 @@ __printf(3, 4)
 void drm_dev_printk(const struct device *dev, const char *level,
 		    const char *format, ...);
 __printf(3, 4)
-void drm_dev_dbg(const struct device *dev, enum drm_debug_category category,
+void _drm_dev_dbg(const struct device *dev, enum drm_debug_category category,
 		 const char *format, ...);
 
 /**
@@ -383,7 +429,7 @@ void drm_dev_dbg(const struct device *dev, enum drm_debug_category category,
  * @fmt: printf() like format string.
  */
 #define DRM_DEV_DEBUG(dev, fmt, ...)					\
-	drm_dev_dbg(dev, DRM_UT_CORE, fmt, ##__VA_ARGS__)
+	drm_dev_dbg(dev, cDRM_UT_CORE, fmt, ##__VA_ARGS__)
 /**
  * DRM_DEV_DEBUG_DRIVER() - Debug output for vendor specific part of the driver
  *
@@ -391,7 +437,7 @@ void drm_dev_dbg(const struct device *dev, enum drm_debug_category category,
  * @fmt: printf() like format string.
  */
 #define DRM_DEV_DEBUG_DRIVER(dev, fmt, ...)				\
-	drm_dev_dbg(dev, DRM_UT_DRIVER,	fmt, ##__VA_ARGS__)
+	drm_dev_dbg(dev, cDRM_UT_DRIVER, fmt, ##__VA_ARGS__)
 /**
  * DRM_DEV_DEBUG_KMS() - Debug output for modesetting code
  *
@@ -399,7 +445,7 @@ void drm_dev_dbg(const struct device *dev, enum drm_debug_category category,
  * @fmt: printf() like format string.
  */
 #define DRM_DEV_DEBUG_KMS(dev, fmt, ...)				\
-	drm_dev_dbg(dev, DRM_UT_KMS, fmt, ##__VA_ARGS__)
+	drm_dev_dbg(dev, cDRM_UT_KMS, fmt, ##__VA_ARGS__)
 
 /*
  * struct drm_device based logging
@@ -443,25 +489,25 @@ void drm_dev_dbg(const struct device *dev, enum drm_debug_category category,
 
 
 #define drm_dbg_core(drm, fmt, ...)					\
-	drm_dev_dbg((drm)->dev, DRM_UT_CORE, fmt, ##__VA_ARGS__)
+	drm_dev_dbg((drm)->dev, cDRM_UT_CORE, fmt, ##__VA_ARGS__)
 #define drm_dbg(drm, fmt, ...)						\
-	drm_dev_dbg((drm)->dev, DRM_UT_DRIVER, fmt, ##__VA_ARGS__)
+	drm_dev_dbg((drm)->dev, cDRM_UT_DRIVER, fmt, ##__VA_ARGS__)
 #define drm_dbg_kms(drm, fmt, ...)					\
-	drm_dev_dbg((drm)->dev, DRM_UT_KMS, fmt, ##__VA_ARGS__)
+	drm_dev_dbg((drm)->dev, cDRM_UT_KMS, fmt, ##__VA_ARGS__)
 #define drm_dbg_prime(drm, fmt, ...)					\
-	drm_dev_dbg((drm)->dev, DRM_UT_PRIME, fmt, ##__VA_ARGS__)
+	drm_dev_dbg((drm)->dev, cDRM_UT_PRIME, fmt, ##__VA_ARGS__)
 #define drm_dbg_atomic(drm, fmt, ...)					\
-	drm_dev_dbg((drm)->dev, DRM_UT_ATOMIC, fmt, ##__VA_ARGS__)
+	drm_dev_dbg((drm)->dev, cDRM_UT_ATOMIC, fmt, ##__VA_ARGS__)
 #define drm_dbg_vbl(drm, fmt, ...)					\
-	drm_dev_dbg((drm)->dev, DRM_UT_VBL, fmt, ##__VA_ARGS__)
+	drm_dev_dbg((drm)->dev, cDRM_UT_VBL, fmt, ##__VA_ARGS__)
 #define drm_dbg_state(drm, fmt, ...)					\
-	drm_dev_dbg((drm)->dev, DRM_UT_STATE, fmt, ##__VA_ARGS__)
+	drm_dev_dbg((drm)->dev, cDRM_UT_STATE, fmt, ##__VA_ARGS__)
 #define drm_dbg_lease(drm, fmt, ...)					\
-	drm_dev_dbg((drm)->dev, DRM_UT_LEASE, fmt, ##__VA_ARGS__)
+	drm_dev_dbg((drm)->dev, cDRM_UT_LEASE, fmt, ##__VA_ARGS__)
 #define drm_dbg_dp(drm, fmt, ...)					\
-	drm_dev_dbg((drm)->dev, DRM_UT_DP, fmt, ##__VA_ARGS__)
+	drm_dev_dbg((drm)->dev, cDRM_UT_DP, fmt, ##__VA_ARGS__)
 #define drm_dbg_drmres(drm, fmt, ...)					\
-	drm_dev_dbg((drm)->dev, DRM_UT_DRMRES, fmt, ##__VA_ARGS__)
+	drm_dev_dbg((drm)->dev, cDRM_UT_DRMRES, fmt, ##__VA_ARGS__)
 
 
 /*
@@ -471,7 +517,7 @@ void drm_dev_dbg(const struct device *dev, enum drm_debug_category category,
  */
 
 __printf(2, 3)
-void __drm_dbg(enum drm_debug_category category, const char *format, ...);
+void ___drm_dbg(enum drm_debug_category category, const char *format, ...);
 __printf(1, 2)
 void __drm_err(const char *format, ...);
 
@@ -500,29 +546,30 @@ void __drm_err(const char *format, ...);
 #define DRM_ERROR_RATELIMITED(fmt, ...)					\
 	DRM_DEV_ERROR_RATELIMITED(NULL, fmt, ##__VA_ARGS__)
 
+
 #define DRM_DEBUG(fmt, ...)						\
-	__drm_dbg(DRM_UT_CORE, fmt, ##__VA_ARGS__)
+	__drm_dbg(cDRM_UT_CORE, fmt, ##__VA_ARGS__)
 
 #define DRM_DEBUG_DRIVER(fmt, ...)					\
-	__drm_dbg(DRM_UT_DRIVER, fmt, ##__VA_ARGS__)
+	__drm_dbg(cDRM_UT_DRIVER, fmt, ##__VA_ARGS__)
 
 #define DRM_DEBUG_KMS(fmt, ...)						\
-	__drm_dbg(DRM_UT_KMS, fmt, ##__VA_ARGS__)
+	__drm_dbg(cDRM_UT_KMS, fmt, ##__VA_ARGS__)
 
 #define DRM_DEBUG_PRIME(fmt, ...)					\
-	__drm_dbg(DRM_UT_PRIME, fmt, ##__VA_ARGS__)
+	__drm_dbg(cDRM_UT_PRIME, fmt, ##__VA_ARGS__)
 
 #define DRM_DEBUG_ATOMIC(fmt, ...)					\
-	__drm_dbg(DRM_UT_ATOMIC, fmt, ##__VA_ARGS__)
+	__drm_dbg(cDRM_UT_ATOMIC, fmt, ##__VA_ARGS__)
 
 #define DRM_DEBUG_VBL(fmt, ...)						\
-	__drm_dbg(DRM_UT_VBL, fmt, ##__VA_ARGS__)
+	__drm_dbg(cDRM_UT_VBL, fmt, ##__VA_ARGS__)
 
 #define DRM_DEBUG_LEASE(fmt, ...)					\
-	__drm_dbg(DRM_UT_LEASE, fmt, ##__VA_ARGS__)
+	__drm_dbg(cDRM_UT_LEASE, fmt, ##__VA_ARGS__)
 
 #define DRM_DEBUG_DP(fmt, ...)						\
-	__drm_dbg(DRM_UT_DP, fmt, ## __VA_ARGS__)
+	__drm_dbg(cDRM_UT_DP, fmt, ## __VA_ARGS__)
 
 #define __DRM_DEFINE_DBG_RATELIMITED(category, drm, fmt, ...)					\
 ({												\
@@ -530,7 +577,7 @@ void __drm_err(const char *format, ...);
 	const struct drm_device *drm_ = (drm);							\
 												\
 	if (drm_debug_enabled(DRM_UT_ ## category) && __ratelimit(&rs_))			\
-		drm_dev_printk(drm_ ? drm_->dev : NULL, KERN_DEBUG, fmt, ## __VA_ARGS__);	\
+		drm_dev_dbg(NULL, cDRM_UT_KMS, fmt, ##__VA_ARGS__);	\
 })
 
 #define drm_dbg_kms_ratelimited(drm, fmt, ...) \
-- 
2.31.1

[RFC PATCH 3/4] drm: fixup DRM_DEBUG_KMS_RATELIMITED merge punt

[Jim Cromie]

HEAD~2 punted on merging DRM_DEBUG_KMS_RATELIMITED; clean that up now,
removing the extra macro indirections which support !KMS cases, since
only _KMS_RATELIMITED is used.  They can be re-added once needed.

conflict was here:
c5261e93758a drm/print: Fixup DRM_DEBUG_KMS_RATELIMITED()

Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
 include/drm/drm_print.h | 19 +++++++------------
 1 file changed, 7 insertions(+), 12 deletions(-)

diff --git a/include/drm/drm_print.h b/include/drm/drm_print.h
index 616fe5e83b50..9812bf11c1e9 100644
--- a/include/drm/drm_print.h
+++ b/include/drm/drm_print.h
@@ -571,20 +571,15 @@ void __drm_err(const char *format, ...);
 #define DRM_DEBUG_DP(fmt, ...)						\
 	__drm_dbg(cDRM_UT_DP, fmt, ## __VA_ARGS__)
 
-#define __DRM_DEFINE_DBG_RATELIMITED(category, drm, fmt, ...)					\
-({												\
-	static DEFINE_RATELIMIT_STATE(rs_, DEFAULT_RATELIMIT_INTERVAL, DEFAULT_RATELIMIT_BURST);\
-	const struct drm_device *drm_ = (drm);							\
-												\
-	if (drm_debug_enabled(DRM_UT_ ## category) && __ratelimit(&rs_))			\
-		drm_dev_dbg(NULL, cDRM_UT_KMS, fmt, ##__VA_ARGS__);	\
+#define DRM_DEBUG_KMS_RATELIMITED(fmt, ...)				\
+({									\
+	static DEFINE_RATELIMIT_STATE(rs_, DEFAULT_RATELIMIT_INTERVAL,	\
+				      DEFAULT_RATELIMIT_BURST);		\
+									\
+	if (drm_debug_enabled(DRM_UT_KMS) && __ratelimit(&rs_))		\
+		__drm_dbg(cDRM_UT_KMS, fmt, ##__VA_ARGS__);		\
 })
 
-#define drm_dbg_kms_ratelimited(drm, fmt, ...) \
-	__DRM_DEFINE_DBG_RATELIMITED(KMS, drm, fmt, ## __VA_ARGS__)
-
-#define DRM_DEBUG_KMS_RATELIMITED(fmt, ...) drm_dbg_kms_ratelimited(NULL, fmt, ## __VA_ARGS__)
-
 /*
  * struct drm_device based WARNs
  *
-- 
2.31.1

[RFC PATCH 4/4] i915: map gvt pr_debug categories to bits in parameters/debug_gvt

[Jim Cromie]

The gvt component of this driver has ~120 pr_debugs, in 9 "classes".
Following model of drm.debug, add a parameter to map bits to these
classes.

In Makefile, add DYNAMIC_DEBUG_MODULE if CONFIG_DRM_USE_DYNAMIC_DEBUG.
In i915_params.c, add callback to map bits to queries.

TBD: consider moving the callback code into lib/dynamic_debug, it
might make for a declarative interface, like an adorned version of:

 +static char *format_prefix_classes[] = {
 +       "gvt: cmd: ",

Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
 drivers/gpu/drm/i915/gvt/Makefile  |  4 ++
 drivers/gpu/drm/i915/i915_params.c | 76 ++++++++++++++++++++++++++++++
 2 files changed, 80 insertions(+)

diff --git a/drivers/gpu/drm/i915/gvt/Makefile b/drivers/gpu/drm/i915/gvt/Makefile
index ea8324abc784..846ba73b8de6 100644
--- a/drivers/gpu/drm/i915/gvt/Makefile
+++ b/drivers/gpu/drm/i915/gvt/Makefile
@@ -7,3 +7,7 @@ GVT_SOURCE := gvt.o aperture_gm.o handlers.o vgpu.o trace_points.o firmware.o \
 
 ccflags-y				+= -I $(srctree)/$(src) -I $(srctree)/$(src)/$(GVT_DIR)/
 i915-y					+= $(addprefix $(GVT_DIR)/, $(GVT_SOURCE))
+
+#ifdef CONFIG_DRM_USE_DYNAMIC_DEBUG
+ccflags-y	+= -DDYNAMIC_DEBUG_MODULE
+#endif
diff --git a/drivers/gpu/drm/i915/i915_params.c b/drivers/gpu/drm/i915/i915_params.c
index 0320878d96b0..13757f1f6b60 100644
--- a/drivers/gpu/drm/i915/i915_params.c
+++ b/drivers/gpu/drm/i915/i915_params.c
@@ -265,3 +265,79 @@ void i915_params_free(struct i915_params *params)
 	I915_PARAMS_FOR_EACH(FREE);
 #undef FREE
 }
+
+/* POC for callback -> dynamic_debug_exec_queries */
+unsigned long __gvt_debug;
+EXPORT_SYMBOL(__gvt_debug);
+
+static char *format_prefix_classes[] = {
+	"gvt: cmd: ",
+	"gvt: core: ",
+	"gvt: dpy: ",
+	"gvt: el: ",
+	"gvt: irq: ",
+	"gvt: mm: ",
+	"gvt: mmio: ",
+	"gvt: render: ",
+	"gvt: sched: "
+};
+#define NUM_CLASSES	ARRAY_SIZE(format_prefix_classes)
+#define OUR_QUERY_SIZE	128 /* we need about 20 */
+
+#include <linux/module.h>
+
+static int param_set_dyndbg(const char *instr, const struct kernel_param *kp)
+{
+	unsigned int val;
+	unsigned long changes, result;
+	int rc, chgct = 0, totct = 0, bitpos;
+	char query[OUR_QUERY_SIZE];
+
+	rc = kstrtouint(instr, 0, &val);
+	if (rc) {
+		pr_err("set_dyndbg: failed\n");
+		return -EINVAL;
+	}
+	result = val;
+	pr_info("set_dyndbg: result:0x%lx from %s\n", result, instr);
+
+	changes = result ^ __gvt_debug;
+
+	for_each_set_bit(bitpos, &changes, NUM_CLASSES) {
+
+		sprintf(query, "format '^%s' %cp", format_prefix_classes[bitpos],
+			test_bit(bitpos, &result) ? '+' : '-');
+
+		chgct = dynamic_debug_exec_queries(query, "i915");
+
+		pr_info("%d changes on: %s\n", chgct, query);
+		totct += chgct;
+	}
+	pr_info("total changes: %d\n", totct);
+	__gvt_debug = result;
+	return 0;
+}
+static int param_get_dyndbg(char *buffer, const struct kernel_param *kp)
+{
+	return scnprintf(buffer, PAGE_SIZE, "%u\n",
+			 *((unsigned int *)kp->arg));
+}
+static const struct kernel_param_ops param_ops_dyndbg = {
+	.set = param_set_dyndbg,
+	.get = param_get_dyndbg,
+};
+
+#define info_ln(hexi, prefix) "\n\t0x" __stringify(hexi) "\t" prefix
+
+MODULE_PARM_DESC(debug_gvt, " gvt debug categories:"
+		 info_ln(1, "gvt: cmd:")
+		 info_ln(2, "gvt: core:")
+		 info_ln(4, "gvt: dpy:")
+		 info_ln(8, "gvt: el:")
+		 info_ln(10, "gvt: irq:")
+		 info_ln(20, "gvt: mm:")
+		 info_ln(40, "gvt: mmio:")
+		 info_ln(80, "gvt: render:")
+		 info_ln(100, "gvt: sched:"));
+
+module_param_cb(debug_gvt, &param_ops_dyndbg, &__gvt_debug, 0644);
-- 
2.31.1