Re: [PATCH] drm: Allow CAP_DUMB_BUFFERS on !MODESET

From: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
To: Ezequiel Garcia <ezequiel@collabora.com>,
	Gustavo Padovan <gustavo@padovan.org>,
	Sean Paul <seanpaul@chromium.org>
Cc: kernel@collabora.com, dri-devel@lists.freedesktop.org
Subject: Re: [PATCH] drm: Allow CAP_DUMB_BUFFERS on !MODESET
Date: Mon, 7 May 2018 11:36:55 +0200	[thread overview]
Message-ID: <451dc7e3-2845-fb1d-d050-c6570b85d29b@linux.intel.com> (raw)
In-Reply-To: <20180504142547.12930-1-ezequiel@collabora.com>

Op 04-05-18 om 16:25 schreef Ezequiel Garcia:
> It's perfectly possible to get dumb buffers out of drivers
> that don't support modeset. This is the case of vgem,
> which can be used to export dmabuf to run various tests.
> Therefore, move the dumb buffer capability check before
> the mode set check.
>
> Inspired by commit f3f4c4d68a28 ("drm: Allow CAP_PRIME on !MODESET").
>
> Fixes: d5264ed3823a ("drm: Return -ENOTSUPP when called for KMS cap with a non-KMS driver")
> Signed-off-by: Ezequiel Garcia <ezequiel@collabora.com>
> ---
>  drivers/gpu/drm/drm_ioctl.c | 7 +++----
>  1 file changed, 3 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_ioctl.c b/drivers/gpu/drm/drm_ioctl.c
> index af782911c505..deac011a0c25 100644
> --- a/drivers/gpu/drm/drm_ioctl.c
> +++ b/drivers/gpu/drm/drm_ioctl.c
> @@ -244,6 +244,9 @@ static int drm_getcap(struct drm_device *dev, void *data, struct drm_file *file_
>  	case DRM_CAP_SYNCOBJ:
>  		req->value = drm_core_check_feature(dev, DRIVER_SYNCOBJ);
>  		return 0;
> +	case DRM_CAP_DUMB_BUFFER:
> +		req->value |= dev->driver->dumb_create ? 1 : 0;
Why the |= ?
> +		return 0;
>  	}
>  
>  	/* Other caps only work with KMS drivers */
> @@ -251,10 +254,6 @@ static int drm_getcap(struct drm_device *dev, void *data, struct drm_file *file_
>  		return -ENOTSUPP;
>  
>  	switch (req->capability) {
> -	case DRM_CAP_DUMB_BUFFER:
> -		if (dev->driver->dumb_create)
> -			req->value = 1;
> -		break;
>  	case DRM_CAP_VBLANK_HIGH_CRTC:
>  		req->value = 1;
>  		break;


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