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

[Woody Suwalski <terraluna977@gmail.com>]

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@arndb.de>
>> ---
>> 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@gmail.com>
> 
> --- 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@gmail.com>

--- 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);
  	}