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| author | Lyude Paul <lyude@redhat.com> | 2018-07-16 11:44:32 -0400 |
|---|---|---|
| committer | Lyude Paul <lyude@redhat.com> | 2018-07-16 11:47:53 -0400 |
| commit | a18b21929453af70390e14f8dee40acf00d428cb (patch) | |
| tree | 3ba8303aedab7a8db481e0d1a72514e34898867d /include/drm | |
| parent | 71a5cb3eb758b5b3735709c7fca577522eda43d4 (diff) | |
| download | linux-stable-a18b21929453af70390e14f8dee40acf00d428cb.tar.gz linux-stable-a18b21929453af70390e14f8dee40acf00d428cb.tar.bz2 linux-stable-a18b21929453af70390e14f8dee40acf00d428cb.zip | |
drm/dp_helper: Add DP aux channel tracing
This is something we've needed for a very long time now, as it makes
debugging issues with faulty MST hubs along with debugging issues
regarding us interfacing with hubs correctly vastly easier to debug.
Currently this can actually be done if you trace the i2c devices for DP
using ftrace but that's significantly less useful for a couple of
reasons:
- Tracing the i2c devices through ftrace means all of the traces are
going to contain a lot of "garbage" output that we're sending over the
i2c line. Most of this garbage comes from retrying transactions, DRM's
helper library adding extra transactions to work around bad hubs, etc.
- Having a user set up ftrace so that they can provide debugging
information is a lot more difficult then being able to say "just boot
with drm.debug=0x100"
- We can potentially expand upon this tracing in the future to print
debugging information in regards to other DP transactions like MST
sideband transactions
This is inspired by a patch Rob Clark sent to do this a long time back.
Neither of us could find the patch however, so we both assumed it would
probably just be easier to rewrite it anyway.
Cc: Rob Clark <robdclark@gmail.com>
Signed-off-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20180716154432.13433-1-lyude@redhat.com
Diffstat (limited to 'include/drm')
| -rw-r--r-- | include/drm/drm_print.h | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/include/drm/drm_print.h b/include/drm/drm_print.h index e1a46e9991cc..767c90b654c5 100644 --- a/include/drm/drm_print.h +++ b/include/drm/drm_print.h @@ -195,6 +195,7 @@ static inline struct drm_printer drm_debug_printer(const char *prefix) #define DRM_UT_VBL 0x20 #define DRM_UT_STATE 0x40 #define DRM_UT_LEASE 0x80 +#define DRM_UT_DP 0x100 __printf(3, 4) void drm_dev_printk(const struct device *dev, const char *level, @@ -307,6 +308,11 @@ void drm_err(const char *format, ...); #define DRM_DEBUG_LEASE(fmt, ...) \ drm_dbg(DRM_UT_LEASE, fmt, ##__VA_ARGS__) +#define DRM_DEV_DEBUG_DP(dev, fmt, ...) \ + drm_dev_dbg(dev, DRM_UT_DP, fmt, ## __VA_ARGS__) +#define DRM_DEBUG_DP(dev, fmt, ...) \ + drm_dbg(DRM_UT_DP, fmt, ## __VA_ARGS__) + #define _DRM_DEV_DEFINE_DEBUG_RATELIMITED(dev, category, fmt, ...) \ ({ \ static DEFINE_RATELIMIT_STATE(_rs, \ |