[PATCH 1/3] drm: add debug print to update_vblank_count
Ville Syrjälä
ville.syrjala at linux.intel.com
Fri Jun 14 16:19:42 UTC 2019
On Thu, Jun 13, 2019 at 03:18:00PM +0300, Oleg Vasilev wrote:
> Since we are logging all vblank counter updates 30 lines below,
> it is also good to have some details whether and how vblank count
> difference is calculated.
>
> Signed-off-by: Oleg Vasilev <oleg.vasilev at intel.com>
> ---
> drivers/gpu/drm/drm_vblank.c | 10 +++++++---
> 1 file changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c
> index 0d704bddb1a6..603ab105125d 100644
> --- a/drivers/gpu/drm/drm_vblank.c
> +++ b/drivers/gpu/drm/drm_vblank.c
> @@ -241,12 +241,16 @@ static void drm_update_vblank_count(struct drm_device *dev, unsigned int pipe,
> * on the difference in the timestamps and the
> * frame/field duration.
> */
> +
> + DRM_DEBUG_VBL("crtc %u: Calculating number of vblanks."
> + " diff_ns = %lld, framedur_ns = %d)\n",
> + pipe, (long long) diff_ns, framedur_ns);
You can generally extract that info from the timestamps that already
get dumped, but I guess that is a bit of a hassle. So might as well
print the stuff the kernel already calculated for you.
The only downside is that lots of printks from the irq handler bogs
the machine down quite a bit. But these shouldn't be used outside of
short vbl debugging sessions anyway.
Pushed this one to drm-misc-next. Thanks for the patch.
> +
> diff = DIV_ROUND_CLOSEST_ULL(diff_ns, framedur_ns);
>
> if (diff == 0 && in_vblank_irq)
> - DRM_DEBUG_VBL("crtc %u: Redundant vblirq ignored."
> - " diff_ns = %lld, framedur_ns = %d)\n",
> - pipe, (long long) diff_ns, framedur_ns);
> + DRM_DEBUG_VBL("crtc %u: Redundant vblirq ignored\n",
> + pipe);
> } else {
> /* some kind of default for drivers w/o accurate vbl timestamping */
> diff = in_vblank_irq ? 1 : 0;
> --
> 2.21.0
>
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--
Ville Syrjälä
Intel
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