Re: [PATCH] [RESEND] vmwgfx: use monotonic event timestamps

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Thomas Hellstrom wrote:
Hi, Arnd,

Sinclair's on paternal leave and I thought this patch was already in drm-next. My bad.
Dave, is it too late to pull this in for the next merge window?

/Thomas


On 01/16/2018 06:18 PM, Arnd Bergmann wrote:
DRM_VMW_EVENT_FENCE_SIGNALED (struct drm_vmw_event_fence) and
DRM_EVENT_VBLANK (struct drm_event_vblank) pass timestamps in 32-bit
seconds/microseconds format.

As of commit c61eef726a78 ("drm: add support for monotonic vblank
timestamps"), other DRM drivers use monotonic times for drm_event_vblank,
but vmwgfx still uses CLOCK_REALTIME for both events, which suffers from
the y2038/y2106 overflow as well as time jumps.

For consistency, this changes vmwgfx to use ktime_get_ts64 as well,
which solves those problems and avoids the deprecated do_gettimeofday()
function.

This should be transparent to to user space, as long as it doesn't
compare the time against the result of gettimeofday().

Link: https://urldefense.proofpoint.com/v2/url?u=https-3A__patchwork.kernel.org_patch_10076599_&d=DwIBAg&c=uilaK90D4TOVoH58JNXRgQ&r=wnSlgOCqfpNS4d02vP68_E9q2BNMCwfD2OZ_6dCFVQQ&m=8M6vawBo0zDsjbqhzV0xpOwAzX7Zm-uyGlIDnQ7-Gms&s=sHGuz0aoE9aLjVp5GALo8mYrN1bwOHW6mGpJIZmhwAc&e=
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
---
Originally sent on Nov 27. Sinclair Yeh said he'd pick it up
for the next pull request, but it's not in linux-next yet.

Resending the unchanged patch, please pick it up when you have time,
or feel free to ignore this email in case it's already in some tree
that just isn't part of linux-next but will be sent during the
next merge window.
---
  drivers/gpu/drm/vmwgfx/vmwgfx_fence.c | 9 +++++----
  1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_fence.c b/drivers/gpu/drm/vmwgfx/vmwgfx_fence.c
index 6c5c75cf5e6c..9ed544f8958f 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_fence.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_fence.c
@@ -901,11 +901,12 @@ static void vmw_event_fence_action_seq_passed(struct vmw_fence_action *action)
      spin_lock_irq(&dev->event_lock);
        if (likely(eaction->tv_sec != NULL)) {
-        struct timeval tv;
+        struct timespec64 ts;
  -        do_gettimeofday(&tv);
-        *eaction->tv_sec = tv.tv_sec;
-        *eaction->tv_usec = tv.tv_usec;
+        ktime_get_ts64(&ts);
+        /* monotonic time, so no y2038 overflow */
+        *eaction->tv_sec = ts.tv_sec;
+        *eaction->tv_usec = ts.tv_nsec / NSEC_PER_USEC;
      }
        drm_send_event_locked(dev, eaction->event);


Thomas, the same way my DRM patch has disappeared:
Date

	Tue, 19 Dec 2017 11:50:57 -0800
From 	Sinclair Yeh <>
Subject 	Re: [PATCH v.2] 4.15 vmgfx boot warning


	

This looks okay to me.

On Mon, Dec 18, 2017 at 07:26:03PM -0500, Woody Suwalski wrote:
The 4.15 drm_atomic_helper driver shows a warning during boot (both 32 and
64 bit x86)
It is caused by a mismatch between the result of vmw_enable_vblank() and
what the drm_atomic_helper expects:
   /...
   ret = drm_crtc_vblank_get(crtc);
   WARN_ONCE(ret != -EINVAL, "driver forgot to call
drm_crtc_vblank_off()\n");
   /...

Signed-off by: Woody Suwalski <terraluna977@xxxxxxxxx>

--- a/drivers/gpu/drm/drm_atomic_helper.c    2017-12-16 09:55:33.853374561
-0500
+++ b/drivers/gpu/drm/drm_atomic_helper.c    2017-12-16 10:55:56.089090752
-0500
@@ -889,7 +889,7 @@ disable_outputs(struct drm_device *dev,
             continue;

         ret = drm_crtc_vblank_get(crtc);
-        WARN_ONCE(ret != -EINVAL, "driver forgot to call
drm_crtc_vblank_off()\n");
+        WARN_ONCE((ret != -EINVAL && ret != -ENOSYS), "driver forgot to
call drm_crtc_vblank_off()\n");
         if (ret == 0)
             drm_crtc_vblank_put(crtc);
     }


===============================================

The 4.15 drm_atomic_helper driver shows a warning during boot.
It is caused by a mismatch between the result of vmw_enable_vblank() and
what the drm_atomic_helper expects:
    /...
    ret = drm_crtc_vblank_get(crtc);
    WARN_ONCE(ret != -EINVAL, "driver forgot to call drm_crtc_vblank_off()\n");
    /...

Signed-off by: Woody Suwalski <terraluna977@xxxxxxxxx>

--- a/drivers/gpu/drm/drm_atomic_helper.c	2017-12-16 09:55:33.853374561 -0500
+++ b/drivers/gpu/drm/drm_atomic_helper.c	2017-12-16 10:55:56.089090752 -0500
@@ -889,7 +889,7 @@ disable_outputs(struct drm_device *dev,
 			continue;
ret = drm_crtc_vblank_get(crtc);
-		WARN_ONCE(ret != -EINVAL, "driver forgot to call drm_crtc_vblank_off()\n");
+		WARN_ONCE((ret != -EINVAL && ret != -ENOSYS), "driver forgot to call drm_crtc_vblank_off()\n");
 		if (ret == 0)
 			drm_crtc_vblank_put(crtc);
 	}

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