From:   Siddh Raman Pant <code@siddh.me>
To:     Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
        Maxime Ripard <mripard@kernel.org>,
        Thomas Zimmermann <tzimmermann@suse.de>,
        David Airlie <airlied@gmail.com>,
        Daniel Vetter <daniel@ffwll.ch>,
        Jim Cromie <jim.cromie@gmail.com>,
        Sam Ravnborg <sam@ravnborg.org>
Cc:     linux-kernel <linux-kernel@vger.kernel.org>,
        dri-devel <dri-devel@lists.freedesktop.org>
Message-ID: <89f0aa1f26696846c2303527fe4d133bb4ff4bf6.1677395403.git.code@siddh.me>
Subject: [PATCH v7 1/7] drm/print: Fix and add support for NULL as first argument in drm_* macros
Date:   Sun, 26 Feb 2023 12:51:48 +0530
In-Reply-To: <cover.1677395403.git.code@siddh.me>
References: <cover.1677395403.git.code@siddh.me>
MIME-Version: 1.0
Content-Transfer-Encoding: quoted-printable
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Precedence: bulk

Comments say macros DRM_DEBUG_* are deprecated in favor of
drm_dbg_*(NULL, ...), but they have broken support for it,
as the macro will result in `(NULL) ? (NULL)->dev : NULL`.

Thus, fix them by separating logic to get dev ptr in a new
function, which will return the dev ptr if arg is not NULL.
Use it in drm_dbg_*, and also in __DRM_DEFINE_DBG_RATELIMITED,
where a similar (but correct) NULL check was in place.

Also, add support for NULL in __drm_printk, so that all the
drm_* macros will hence support NULL as the first argument.
This also means that deprecation comments mentioning pr_()*
can now be changed to the drm equivalents.

There is a need to support device pointers, as in some cases,
we may not have drm_device but just the device ptr, such as
when dealing with struct mipi_dsi_host. Before this change,
passing just mipi_dsi_host would have worked, since due to
preprocessing, the resultant would be "host->dev", but now
due to NULL check that cannot happen.

Signed-off-by: Siddh Raman Pant <code@siddh.me>
---
 include/drm/drm_print.h | 114 ++++++++++++++++++++++++++++++----------
 1 file changed, 87 insertions(+), 27 deletions(-)

diff --git a/include/drm/drm_print.h b/include/drm/drm_print.h
index a93a387f8a1a..1a7d4064d120 100644
--- a/include/drm/drm_print.h
+++ b/include/drm/drm_print.h
@@ -34,6 +34,7 @@
 #include <linux/dynamic_debug.h>
=20
 #include <drm/drm.h>
+#include <drm/drm_device.h>
=20
 /* Do *not* use outside of drm_print.[ch]! */
 extern unsigned long __drm_debug;
@@ -445,15 +446,73 @@ void __drm_dev_dbg(struct _ddebug *desc, const struct=
 device *dev,
 #define DRM_DEV_DEBUG_KMS(dev, fmt, ...)=09=09=09=09\
 =09drm_dev_dbg(dev, DRM_UT_KMS, fmt, ##__VA_ARGS__)
=20
+/* Helpers for struct drm_device based logging. */
+
+/**
+ * __drm_dev_ptr - Helper function to get drm->dev pointer.
+ * @drm: struct drm_device pointer.
+ *
+ * RETURNS:
+ * The struct device pointer (NULL if @drm is NULL).
+ */
+static inline struct device *__drm_dev_ptr(const struct drm_device *drm)
+{
+=09if (drm)
+=09=09return drm->dev;
+
+=09return NULL;
+}
+
+/**
+ * __dev_ptr - Helper function to get the same device pointer.
+ * @dev: struct device pointer, or NULL.
+ *
+ * RETURNS:
+ * The struct device pointer (NULL if @dev is NULL).
+ */
+static inline struct device *__dev_ptr(const struct device *dev)
+{
+=09return (struct device *)dev;
+}
+
+/**
+ * __get_dev_ptr - Helper to get device pointer given struct drm_device *,
+ *=09=09   or struct device *, or NULL.
+ *
+ * Primarily for use in drm_*() print macros, since they need to handle NU=
LL
+ * as the first argument passed.
+ *
+ * struct device pointers are supported for edge cases (such as mipi_dsi_h=
ost),
+ * the default (and recommended) way is to pass struct drm_device pointer.
+ */
+#define  __get_dev_ptr(drm)=09=09=09\
+=09_Generic((drm),=09=09=09=09\
+=09=09struct device * :=09=09\
+=09=09=09__dev_ptr,=09=09\
+=09=09const struct device * :=09=09\
+=09=09=09__dev_ptr,=09=09\
+=09=09default :=09=09=09\
+=09=09=09__drm_dev_ptr=09=09\
+=09)(drm)
+
 /*
  * struct drm_device based logging
  *
  * Prefer drm_device based logging over device or prink based logging.
+ *
+ * The below macros support device pointers to cope for edge cases where
+ * we only have device (like in mipi_dsi_host) but not drm_device.
  */
=20
 /* Helper for struct drm_device based logging. */
 #define __drm_printk(drm, level, type, fmt, ...)=09=09=09\
-=09dev_##level##type((drm)->dev, "[drm] " fmt, ##__VA_ARGS__)
+({=09=09=09=09=09=09=09=09=09\
+=09struct device *__dev_ =3D __get_dev_ptr(drm);=09=09=09\
+=09if (__dev_)=09=09=09=09=09=09=09\
+=09=09dev_##level##type(__dev_, "[drm] " fmt, ##__VA_ARGS__);=09\
+=09else=09=09=09=09=09=09=09=09\
+=09=09pr_##level##type("[drm] " fmt, ##__VA_ARGS__);=09=09\
+})
=20
=20
 #define drm_info(drm, fmt, ...)=09=09=09=09=09\
@@ -487,25 +546,25 @@ void __drm_dev_dbg(struct _ddebug *desc, const struct=
 device *dev,
=20
=20
 #define drm_dbg_core(drm, fmt, ...)=09=09=09=09=09\
-=09drm_dev_dbg((drm) ? (drm)->dev : NULL, DRM_UT_CORE, fmt, ##__VA_ARGS__)
-#define drm_dbg_driver(drm, fmt, ...)=09=09=09=09=09=09\
-=09drm_dev_dbg((drm) ? (drm)->dev : NULL, DRM_UT_DRIVER, fmt, ##__VA_ARGS_=
_)
+=09drm_dev_dbg(__get_dev_ptr(drm), DRM_UT_CORE, fmt, ##__VA_ARGS__)
+#define drm_dbg_driver(drm, fmt, ...)=09=09=09=09=09\
+=09drm_dev_dbg(__get_dev_ptr(drm), DRM_UT_DRIVER, fmt, ##__VA_ARGS__)
 #define drm_dbg_kms(drm, fmt, ...)=09=09=09=09=09\
-=09drm_dev_dbg((drm) ? (drm)->dev : NULL, DRM_UT_KMS, fmt, ##__VA_ARGS__)
+=09drm_dev_dbg(__get_dev_ptr(drm), DRM_UT_KMS, fmt, ##__VA_ARGS__)
 #define drm_dbg_prime(drm, fmt, ...)=09=09=09=09=09\
-=09drm_dev_dbg((drm) ? (drm)->dev : NULL, DRM_UT_PRIME, fmt, ##__VA_ARGS__=
)
+=09drm_dev_dbg(__get_dev_ptr(drm), DRM_UT_PRIME, fmt, ##__VA_ARGS__)
 #define drm_dbg_atomic(drm, fmt, ...)=09=09=09=09=09\
-=09drm_dev_dbg((drm) ? (drm)->dev : NULL, DRM_UT_ATOMIC, fmt, ##__VA_ARGS_=
_)
+=09drm_dev_dbg(__get_dev_ptr(drm), DRM_UT_ATOMIC, fmt, ##__VA_ARGS__)
 #define drm_dbg_vbl(drm, fmt, ...)=09=09=09=09=09\
-=09drm_dev_dbg((drm) ? (drm)->dev : NULL, DRM_UT_VBL, fmt, ##__VA_ARGS__)
+=09drm_dev_dbg(__get_dev_ptr(drm), DRM_UT_VBL, fmt, ##__VA_ARGS__)
 #define drm_dbg_state(drm, fmt, ...)=09=09=09=09=09\
-=09drm_dev_dbg((drm) ? (drm)->dev : NULL, DRM_UT_STATE, fmt, ##__VA_ARGS__=
)
+=09drm_dev_dbg(__get_dev_ptr(drm), DRM_UT_STATE, fmt, ##__VA_ARGS__)
 #define drm_dbg_lease(drm, fmt, ...)=09=09=09=09=09\
-=09drm_dev_dbg((drm) ? (drm)->dev : NULL, DRM_UT_LEASE, fmt, ##__VA_ARGS__=
)
+=09drm_dev_dbg(__get_dev_ptr(drm), DRM_UT_LEASE, fmt, ##__VA_ARGS__)
 #define drm_dbg_dp(drm, fmt, ...)=09=09=09=09=09\
-=09drm_dev_dbg((drm) ? (drm)->dev : NULL, DRM_UT_DP, fmt, ##__VA_ARGS__)
+=09drm_dev_dbg(__get_dev_ptr(drm), DRM_UT_DP, fmt, ##__VA_ARGS__)
 #define drm_dbg_drmres(drm, fmt, ...)=09=09=09=09=09\
-=09drm_dev_dbg((drm) ? (drm)->dev : NULL, DRM_UT_DRMRES, fmt, ##__VA_ARGS_=
_)
+=09drm_dev_dbg(__get_dev_ptr(drm), DRM_UT_DRMRES, fmt, ##__VA_ARGS__)
=20
 #define drm_dbg(drm, fmt, ...)=09drm_dbg_driver(drm, fmt, ##__VA_ARGS__)
=20
@@ -533,31 +592,31 @@ void __drm_err(const char *format, ...);
 #define _DRM_PRINTK(once, level, fmt, ...)=09=09=09=09\
 =09printk##once(KERN_##level "[" DRM_NAME "] " fmt, ##__VA_ARGS__)
=20
-/* NOTE: this is deprecated in favor of pr_info(). */
+/* NOTE: this is deprecated in favor of drm_info(NULL, ...). */
 #define DRM_INFO(fmt, ...)=09=09=09=09=09=09\
 =09_DRM_PRINTK(, INFO, fmt, ##__VA_ARGS__)
-/* NOTE: this is deprecated in favor of pr_notice(). */
+/* NOTE: this is deprecated in favor of drm_notice(NULL, ...). */
 #define DRM_NOTE(fmt, ...)=09=09=09=09=09=09\
 =09_DRM_PRINTK(, NOTICE, fmt, ##__VA_ARGS__)
-/* NOTE: this is deprecated in favor of pr_warn(). */
+/* NOTE: this is deprecated in favor of drm_warn(NULL, ...). */
 #define DRM_WARN(fmt, ...)=09=09=09=09=09=09\
 =09_DRM_PRINTK(, WARNING, fmt, ##__VA_ARGS__)
=20
-/* NOTE: this is deprecated in favor of pr_info_once(). */
+/* NOTE: this is deprecated in favor of drm_info_once(NULL, ...). */
 #define DRM_INFO_ONCE(fmt, ...)=09=09=09=09=09=09\
 =09_DRM_PRINTK(_once, INFO, fmt, ##__VA_ARGS__)
-/* NOTE: this is deprecated in favor of pr_notice_once(). */
+/* NOTE: this is deprecated in favor of drm_notice_once(NULL, ...). */
 #define DRM_NOTE_ONCE(fmt, ...)=09=09=09=09=09=09\
 =09_DRM_PRINTK(_once, NOTICE, fmt, ##__VA_ARGS__)
-/* NOTE: this is deprecated in favor of pr_warn_once(). */
+/* NOTE: this is deprecated in favor of drm_warn_once(NULL, ...). */
 #define DRM_WARN_ONCE(fmt, ...)=09=09=09=09=09=09\
 =09_DRM_PRINTK(_once, WARNING, fmt, ##__VA_ARGS__)
=20
-/* NOTE: this is deprecated in favor of pr_err(). */
+/* NOTE: this is deprecated in favor of drm_err(NULL, ...). */
 #define DRM_ERROR(fmt, ...)=09=09=09=09=09=09\
 =09__drm_err(fmt, ##__VA_ARGS__)
=20
-/* NOTE: this is deprecated in favor of pr_err_ratelimited(). */
+/* NOTE: this is deprecated in favor of drm_err_ratelimited(NULL, ...). */
 #define DRM_ERROR_RATELIMITED(fmt, ...)=09=09=09=09=09\
 =09DRM_DEV_ERROR_RATELIMITED(NULL, fmt, ##__VA_ARGS__)
=20
@@ -593,13 +652,14 @@ void __drm_err(const char *format, ...);
 #define DRM_DEBUG_DP(fmt, ...)=09=09=09=09=09=09\
 =09__drm_dbg(DRM_UT_DP, fmt, ## __VA_ARGS__)
=20
-#define __DRM_DEFINE_DBG_RATELIMITED(category, drm, fmt, ...)=09=09=09=09=
=09\
-({=09=09=09=09=09=09=09=09=09=09=09=09\
-=09static DEFINE_RATELIMIT_STATE(rs_, DEFAULT_RATELIMIT_INTERVAL, DEFAULT_=
RATELIMIT_BURST);\
-=09const struct drm_device *drm_ =3D (drm);=09=09=09=09=09=09=09\
-=09=09=09=09=09=09=09=09=09=09=09=09\
-=09if (drm_debug_enabled(DRM_UT_ ## category) && __ratelimit(&rs_))=09=09=
=09\
-=09=09drm_dev_printk(drm_ ? drm_->dev : NULL, KERN_DEBUG, fmt, ## __VA_ARG=
S__);=09\
+#define __DRM_DEFINE_DBG_RATELIMITED(category, drm, fmt, ...)=09=09\
+({=09=09=09=09=09=09=09=09=09\
+=09static DEFINE_RATELIMIT_STATE(rs_, DEFAULT_RATELIMIT_INTERVAL,=09\
+=09=09=09=09      DEFAULT_RATELIMIT_BURST);=09=09\
+=09=09=09=09=09=09=09=09=09\
+=09if (drm_debug_enabled(DRM_UT_ ## category) && __ratelimit(&rs_))\
+=09=09drm_dev_printk(__get_dev_ptr(drm), KERN_DEBUG,=09=09\
+=09=09=09       fmt, ## __VA_ARGS__);=09=09=09\
 })
=20
 #define drm_dbg_kms_ratelimited(drm, fmt, ...) \
--=20
2.39.1