Re: [PATCH 7/8] drm/irq: Implement a generic vblank_wait function

Daniel Vetter
2014-07-31T09:46:09Z

On Thu, Jul 31, 2014 at 10:56 AM, Michel Dänzer <michel@daenzer.net> wrote:
> On 31.07.2014 16:54, Daniel Vetter wrote:
>> On Thu, Jul 31, 2014 at 3:14 AM, Michel Dänzer <michel@daenzer.net> wrote:
>>> I think it would be better to refactor drm_wait_vblank() than to
>>> reinvent it.
>>
>> That's the ioctl implementation which spends most of its time decoding
>> ioctl structures. If we take that out then there's about half a line
>> which would be shared (since a lot of the stuff in there is ums gunk
>> that we don't want to carry over to a kms-only internal interface). So
>> imo that doesn't make sense.
>
> I'm referring to the core logic of waiting for a number of vblank
> periods or until the vblank period with a given sequence number, dealing
> with wraparound etc. The issues you guys were discussing for a new
> function were ironed out there long ago.

I'm referering to the same, but that logic is gunked up with
special-cases for UMS and absolute vblank waits and all kinds of other
stuff, so that sharing this with a kms helper to wait a few vblanks
(so relative only) really doesn't buy us all that much. Actually I
think you'll be left with nothing shared since for the kms
driver-internal functions really shouldn't have all these hacks to
paper over races and other issues (like ums shutting down the pipe
while we didn't look).
-Daniel
--
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch
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