On Mon, Jul 31, 2017 at 10:03:04PM -0700, Keith Packard wrote:
This modifies the datatypes used by the vblank code to provide both 64 bits of vblank count and switch to using ktime_t for timestamps to increase resolution from microseconds to nanoseconds.
The driver interfaces have been left using 32 bits of vblank count; all of the code necessary to widen that value for the user API was already included to handle devices returning fewer than 32-bits.
This will provide the necessary datatypes for the Vulkan API.
v2:
Re-write wait_vblank ioctl to ABSOLUTE sequence
When an application uses the WAIT_VBLANK ioctl with RELATIVE or NEXTONMISS bits set, the target vblank interval is updated within the kernel. We need to write that target back to the ioctl buffer and update the flags bits so that if the wait is interrupted by a signal, when it is re-started, it will target precisely the same vblank count as before.
Leave driver API with 32-bit vblank count
Suggested-by: Michel Dänzer michel@daenzer.net Suggested-by: Daniel Vetter daniel@ffwll.ch Signed-off-by: Keith Packard keithp@keithp.com
Subject is a bit confusing since you say uapi, but this is just the internal prep work. Dropping UAPI fixes that. With that fixed:
Reviewed-by: Daniel Vetter daniel.vetter@ffwll.ch
Two more optional comments below, feel free to adapt or ignore. I'll wait for Michel's r-b before merging either way.
static int drm_queue_vblank_event(struct drm_device *dev, unsigned int pipe,
u64 req_seq, union drm_wait_vblank *vblwait,
Minor bikeshed: Since you pass the requested vblank number explicit, mabye also pass the user_data explicit and remove the vblwait struct from the parameter list? Restricts the old uapi cruft a bit.
/*
- Widen a 32-bit param to 64-bits.
- \param narrow 32-bit value (missing upper 32 bits)
- \param near 64-bit value that should be 'close' to near
- This function returns a 64-bit value using the lower 32-bits from
- 'narrow' and constructing the upper 32-bits so that the result is
- as close as possible to 'near'.
- */
+static u64 widen_32_to_64(u32 narrow, u64 near) +{
- u64 wide = narrow | (near & 0xffffffff00000000ULL);
- if ((int64_t) (wide - near) > 0x80000000LL)
wide -= 0x100000000ULL;- else if ((int64_t) (near - wide) > 0x80000000LL)
wide += 0x100000000ULL;- return wide;
return near + (int32_s) ((uint32_t)wide - near) ?
But then it took me way too long to think about this one, so maybe leave it at that.
Cheers, Daniel