On 30/11/16 06:07 PM, Daniel Vetter wrote:
> On Wed, Nov 30, 2016 at 05:30:02PM +0900, Michel Dänzer wrote:
>> From: Michel Dänzer <michel.daenzer@xxxxxxx>
>>
>> This is an attempt to make the previous fix a bit more robust going
>> forward.
>>
>> Signed-off-by: Michel Dänzer <michel.daenzer@xxxxxxx>
>> ---
>> drivers/gpu/drm/drm_ioctl.c | 23 +++++++++++++++++------
>> 1 file changed, 17 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/drm_ioctl.c b/drivers/gpu/drm/drm_ioctl.c
>> index 71c3473..32f484b 100644
>> --- a/drivers/gpu/drm/drm_ioctl.c
>> +++ b/drivers/gpu/drm/drm_ioctl.c
>> @@ -229,6 +229,19 @@ static int drm_getcap(struct drm_device *dev, void *data, struct drm_file *file_
>> struct drm_crtc *crtc;
>>
>> req->value = 0;
>> +
>> + /* Only allow non-KMS caps with non-KMS drivers */
>> + switch (req->capability) {
>> + case DRM_CAP_DUMB_BUFFER:
>
> Dumb buffers are only meant to be used for kms drivers, should be
> disallowed too.
>
>> + case DRM_CAP_VBLANK_HIGH_CRTC:
>
> Might be good to have a comment here that we need to allow this for old
> ums?
This is effectively KMS-only as well, per Alex (thanks!).
>> + case DRM_CAP_PRIME:
>> + case DRM_CAP_TIMESTAMP_MONOTONIC:
>
> This is pretty new, I don't think any of the old ums drivers was ever
> updated to use it. Should probably disallow it too.
DRM_CAP_TIMESTAMP_MONOTONIC is driver independent, I don't see why it
wouldn't work fine with UMS drivers. OTOH, I don't think DRM_CAP_PRIME
can work with UMS.
>> + break;
>> + default:
>> + if (!drm_core_check_feature(dev, DRIVER_MODESET))
>> + return -ENOTSUPP;
>> + }
>
> And one code org bikeshed: I don't like the duplicated switch, could we
> instead split it it into two disjoint sets like this?
>
> switch (req->capability) {
> case DRM_CAP_PRIME:
> req->value |= dev->driver->prime_fd_to_handle ? DRM_PRIME_CAP_IMPORT : 0;
> req->value |= dev->driver->prime_handle_to_fd ? DRM_PRIME_CAP_EXPORT : 0;
> break;
> ... all other non-modeset caps ...
> }
>
> if (!drm_core_check_feature(dev, DRIVER_MODESET))
> return -ENOTSUPP;
>
> switch (req->capability) {
> ... handle remaining caps needed for DRIVER_MODSET ...
> default:
> return -EINVAL;
> }
>
> That way it would be a bit more obvious that people who add a new cap need
> to make a decision where to put it (and by default put it in the bottom
> pile).
Your pseudo-code wouldn't work correctly, but I get your idea. :)
v2 addressing review feedback coming up soon.
--
Earthling Michel Dänzer | http://www.amd.com
Libre software enthusiast | Mesa and X developer
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