linux-kernel - Re: [PATCH] 4.15 vmgfx boot warning

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Message-ID: <20171213212522.GC16788@promb-2n-dhcp36.eng.vmware.com>
Date:   Wed, 13 Dec 2017 13:25:23 -0800
From:   Sinclair Yeh <syeh@...are.com>
To:     Woody Suwalski <terraluna977@...il.com>
Cc:     DRI mailing list <dri-devel@...ts.freedesktop.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Dave Airlie <airlied@...ux.ie>
Subject: Re: [PATCH] 4.15 vmgfx boot warning

Hi Woody,

On Wed, Nov 22, 2017 at 04:05:50PM -0500, Woody Suwalski wrote:
> The 4.15 vmwgfx driver shows a warning during boot (32 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");

This doesn't apply to us because we don't have vblank support, and so
-ENOSYS seems to be the right error.

In the commit message for 84014b0a39ee, it does state a check for this
condition, but the check itself is based on dev->irq_enabled.

Is there another way to check for vblank support?



>    /...
> 
> Signed-off by: Woody Suwalski <terraluna977@...il.com>
> 
> --- a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c    2017-11-22 15:29:46.511674079
> -0500
> +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c    2017-11-22 15:30:35.344559592
> -0500
> @@ -1869,7 +1869,7 @@ u32 vmw_get_vblank_counter(struct drm_de
>   */
>  int vmw_enable_vblank(struct drm_device *dev, unsigned int pipe)
>  {
> -    return -ENOSYS;
> +    return -EINVAL;
>  }
> 
>  /**
>