417dd041a215007ea98c5bb56989da2ac4f287ed5df68e0f0625c121.patch

From ff8518f0bab439ff1fb282d5efa3f1bc47d09ded Mon Sep 17 00:00:00 2001
From: Sean Paul <seanpaul@chromium.org>
Date: Tue, 18 Aug 2020 17:05:06 -0400
Subject: [PATCH] CHROMIUM: drm/print: Add drm_debug_category_printer

This patch adds a new printer which will select the appropriate output
for a given debug category. Currently there is only one output target,
which is syslog. However in the future we'll have tracefs and it will be
useful to print to syslog, tracefs, or both. Drivers just need to create
the printer for the appropriate category and the printer will decide
where to send the output.

Signed-off-by: Sean Paul <seanpaul@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20200608210505.48519-11-sean@poorly.run #v5

Changes in v5:
-Added to the set
Changes in v6:
-None
(am from https://patchwork.freedesktop.org/patch/386275/)
(also found at https://lore.kernel.org/r/20200818210510.49730-11-sean@poorly.run)

Downstream reason:
-Patchset needs more work to resolve dynamic debug conflicts and
 adoption upstream

BUG=b:193917467
TEST=Tested on volteer/zork/trogdor. Build tested on others

Change-Id: I989519a871c52c018859a1447d2fffcdc87eadd5
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/3260467
Reviewed-by: Drew Davenport <ddavenport@chromium.org>
Tested-by: Sean Paul <seanpaul@chromium.org>
Commit-Queue: Sean Paul <seanpaul@chromium.org>
---
 drivers/gpu/drm/drm_print.c |  5 +++++
 include/drm/drm_print.h     | 28 ++++++++++++++++++++++++++++
 2 files changed, 33 insertions(+)

diff --git a/drivers/gpu/drm/drm_print.c b/drivers/gpu/drm/drm_print.c
index d0133fb3b6172f5c5b50ce93fb97beb3c6709c36..f2da392059e892524972e3e5146b8a287c5c9519 100644
--- a/drivers/gpu/drm/drm_print.c
+++ b/drivers/gpu/drm/drm_print.c
@@ -214,6 +214,11 @@ void __drm_printfn_err(struct drm_printer *p, struct va_format *vaf)
 }
 EXPORT_SYMBOL(__drm_printfn_err);
 
+void __drm_printfn_noop(struct drm_printer *p, struct va_format *vaf)
+{
+}
+EXPORT_SYMBOL(__drm_printfn_noop);
+
 /**
  * drm_puts - print a const string to a &drm_printer stream
  * @p: the &drm printer
diff --git a/include/drm/drm_print.h b/include/drm/drm_print.h
index 0cf4f619afd908b081766c158447c93a49dfa343..45e2ddab14c9aabde3aab58574af54032218442e 100644
--- a/include/drm/drm_print.h
+++ b/include/drm/drm_print.h
@@ -191,6 +191,7 @@ 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_err(struct drm_printer *p, struct va_format *vaf);
+void __drm_printfn_noop(struct drm_printer *p, struct va_format *vaf);
 
 __printf(2, 3)
 void drm_printf(struct drm_printer *p, const char *f, ...);
@@ -362,6 +363,33 @@ static inline struct drm_printer drm_err_printer(struct drm_device *drm,
 	return p;
 }
 
+/**
+ * drm_debug_category_printer - construct a &drm_printer that outputs to
+ * pr_debug() if enabled for the given category.
+ * @category: the DRM_UT_* message category this message belongs to
+ * @prefix: trace output prefix
+ *
+ * RETURNS:
+ * The &drm_printer object
+ */
+static inline struct drm_printer
+drm_debug_category_printer(enum drm_debug_category category,
+			   const char *prefix)
+{
+	struct drm_printer p = {
+		.prefix = prefix
+	};
+
+	if (drm_debug_syslog_enabled(category)) {
+		p.printfn = __drm_printfn_debug_syslog;
+	} else {
+		WARN(1, "Debug category %d is inactive.", category);
+		p.printfn = __drm_printfn_noop;
+	}
+
+	return p;
+}
+
 /*
  * struct device based logging
  *
-- 
2.44.0.478.gd926399ef9-goog