On Thu, Apr 03, 2014 at 02:28:32PM +0530, Archit Taneja wrote:
On Wednesday 02 April 2014 06:41 PM, Rob Clark wrote:
On Wed, Apr 2, 2014 at 5:52 AM, Archit Taneja archit@ti.com wrote:
Hi,
I was trying to figure out how we are supposed to manage synchronization between a mode_set and a page_flip called on a crtc.
Say, if a mode_set is immediately followed by a page_flip. The driver can't process the page_flip straight away since the hardware is still completing the mode_set.
I guess setcrtc is expected to be synchronous(ish).. so a lot of userspace won't expect the first pageflip to fail with -EBUSY.
Okay, thanks. I guess having setcrtc synchronous isn't that bad.
Yeah, atm I think the rules are that pageflip can only return -EBUSY if there's still a pageflip ongoing. Everything else is presumed to be at least implicitly ordered, so if your hw can do async modesets then you need to synchronize. Also if there's still a pageflip outstanding you need to wait for that to complete in your set_config callback first (usually in the set_base or the crtc->disable/prepare hooks when using the crtc helpers). -Daniel