[03/13] drm: Add drm_puts() to complement drm_printf()

Commit Message

Jordan Crouse July 24, 2018, 4:33 p.m. UTC

Add drm_puts() for a much faster path to print constant strings
into a drm_printer object with memcpy and friends. This can
have seconds off of really large outputs such as GPU dumps.

If the drm_printer object supports a custom puts function then
use that otherwise fall back to the slower legacy printf call.

v2: Add documentation for drm_puts() per Daniel Vetter

Reviewed-by: Daniel Vetter <[e-mail]>
Signed-off-by: Jordan Crouse <[e-mail]>
---
 drivers/gpu/drm/drm_print.c | 17 +++++++++++++++++
 include/drm/drm_print.h     |  2 ++
 2 files changed, 19 insertions(+)

Comments

Emil Velikov July 24, 2018, 6:10 p.m. UTC | #1

Hi Jordan,

I might be a bit late for the party, so consider the following jfyi.

On 24 July 2018 at 17:33, Jordan Crouse <[e-mail]> wrote:

> +void drm_puts(struct drm_printer *p, const char *str)
One could easily use the compiler to detect if drm_printf or drm_puts
should be used. See the trace_printk define in include/linux/kernel.h.

> +{
> +       if (p->puts)
> +               p->puts(p, str);
> +       else
> +               drm_printf(p, "%s", str);

From a quick look from the existing three printers (seq_file, info and
debug) only the first one is updated with this series.
I would imagine that updating the other two and dropping the
drm_printf() fallback is a good move.

Otherwise one could easily assume that they have a fast path when they do not.

HTH
Emil

Patch

diff --git a/drivers/gpu/drm/drm_print.c b/drivers/gpu/drm/drm_print.c
index 03d1f98e5ac7..4bcd960788ba 100644
--- a/drivers/gpu/drm/drm_print.c
+++ b/drivers/gpu/drm/drm_print.c
@@ -122,6 +122,23 @@  void __drm_printfn_debug(struct drm_printer *p, struct va_format *vaf)
 }
 EXPORT_SYMBOL(__drm_printfn_debug);
 
+/**
+ * drm_puts - print a const string to a &drm_printer stream
+ * @p: the &drm printer
+ * @f: const string
+ *
+ * Allow &drm_printer types that have a constant string
+ * option to use it.
+ */
+void drm_puts(struct drm_printer *p, const char *str)
+{
+	if (p->puts)
+		p->puts(p, str);
+	else
+		drm_printf(p, "%s", str);
+}
+EXPORT_SYMBOL(drm_puts);
+
 /**
  * drm_printf - print to a &drm_printer stream
  * @p: the &drm_printer
diff --git a/include/drm/drm_print.h b/include/drm/drm_print.h
index 3213d2896e9c..06167a30f165 100644
--- a/include/drm/drm_print.h
+++ b/include/drm/drm_print.h
@@ -69,6 +69,7 @@ 
 struct drm_printer {
 	/* private: */
 	void (*printfn)(struct drm_printer *p, struct va_format *vaf);
+	void (*puts)(struct drm_printer *p, const char *str);
 	void *arg;
 	const char *prefix;
 };
@@ -80,6 +81,7 @@  void __drm_printfn_debug(struct drm_printer *p, struct va_format *vaf);
 
 __printf(2, 3)
 void drm_printf(struct drm_printer *p, const char *f, ...);
+void drm_puts(struct drm_printer *p, const char *str);
 
 __printf(2, 0)
 /**