linux-kernel - Re: [PATCH 0/4] drm: core: Convert logging to drm

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Date:   Sat, 11 Jul 2020 11:16:33 -0700
From:   Joe Perches <joe@...ches.com>
To:     Suraj Upadhyay <usuraj35@...il.com>,
        Sam Ravnborg <sam@...nborg.org>,
        maarten.lankhorst@...ux.intel.com, mripard@...nel.org,
        tzimmermann@...e.de, airlied@...ux.ie, daniel@...ll.ch
Cc:     linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH 0/4] drm: core: Convert logging to drm_* functions.

On Sat, 2020-07-11 at 20:41 +0530, Suraj Upadhyay wrote:
> On Fri, Jul 10, 2020 at 07:56:43PM +0200, Sam Ravnborg wrote:
> > Hi Suraj.
> > 
> > On Tue, Jul 07, 2020 at 10:04:14PM +0530, Suraj Upadhyay wrote:
> > > This patchset converts logging to drm_* functions in drm core.
> > > 
> > > The following functions have been converted to their respective
> > > DRM alternatives :
> > > dev_info()      --> drm_info()
> > > dev_err()       --> drm_err()
> > > dev_warn()      --> drm_warn()
> > > dev_err_once()  --> drm_err_once().
> > 
> > I would prefer that DRM_* logging in the same files are converted in the
> > same patch. So we have one logging conversion patch for each file you
> > touches and that we do not need to re-vist the files later to change
> > another set of logging functions.
> 
> Agreed.
> 
> > If possible WARN_* should also be converted to drm_WARN_*
> > If patch is too large, then split them up but again lets have all
> > logging updated when we touch a file.
> > 
> > Care to take a look at this approach?
> > 
> 
> Hii,
> 	The problem with WARN_* macros is that they are used without any
> drm device context. For example [this use here](https://cgit.freedesktop.org/drm/drm-misc/tree/drivers/gpu/drm/drm_edid.c#n1667) in drm_edid.c,
> doesn't have a drm device context and only has one argument (namely !raw_edid).
> There are many more such use cases.
> 
> And also there were cases where dev_* logging functions didn't have any
> drm_device context.

Perhaps change the __drm_printk macro to not
dereference the drm argument when NULL.

A trivial but perhaps inefficient way might be
used like:

	drm_<level>(NULL, fmt, ...)

---
 include/drm/drm_print.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/drm/drm_print.h b/include/drm/drm_print.h
index 1c9417430d08..9323a8f46b3c 100644
--- a/include/drm/drm_print.h
+++ b/include/drm/drm_print.h
@@ -395,8 +395,8 @@ void drm_dev_dbg(const struct device *dev, enum drm_debug_category category,
 
 /* Helper for struct drm_device based logging. */
 #define __drm_printk(drm, level, type, fmt, ...)			\
-	dev_##level##type((drm)->dev, "[drm] " fmt, ##__VA_ARGS__)
-
+	dev_##level##type((drm) ? (drm)->dev : NULL, "[drm] " fmt,	\
+			  ##__VA_ARGS__)
 
 #define drm_info(drm, fmt, ...)					\
 	__drm_printk((drm), info,, fmt, ##__VA_ARGS__)