[asahilinux:asahi-wip 29/31] drivers/gpu/drm/apple/dcp.c:101: warning: Function parameter or struct member 'crtc' not described in 'dcp_crtc_send_page_flip_event'

[kernel test robot <lkp@intel.com>]

tree:   https://github.com/AsahiLinux/linux asahi-wip
head:   65718aefab870e7d3ab6c1863cb9dc2773712312
commit: 64bf00b0969fcf8f27cb21e4db4a0741b47cfdda [29/31] drm: apple: Override drm_vblank's page flip event handling [HACK]
config: arm64-allmodconfig (https://download.01.org/0day-ci/archive/20240513/202405131641.E3WM7KFH-lkp@intel.com/config)
compiler: clang version 19.0.0git (https://github.com/llvm/llvm-project b910bebc300dafb30569cecc3017b446ea8eafa0)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240513/202405131641.E3WM7KFH-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202405131641.E3WM7KFH-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> drivers/gpu/drm/apple/dcp.c:101: warning: Function parameter or struct member 'crtc' not described in 'dcp_crtc_send_page_flip_event'
>> drivers/gpu/drm/apple/dcp.c:101: warning: Function parameter or struct member 'e' not described in 'dcp_crtc_send_page_flip_event'
>> drivers/gpu/drm/apple/dcp.c:101: warning: Function parameter or struct member 'now' not described in 'dcp_crtc_send_page_flip_event'
>> drivers/gpu/drm/apple/dcp.c:101: warning: Function parameter or struct member 'start' not described in 'dcp_crtc_send_page_flip_event'


vim +101 drivers/gpu/drm/apple/dcp.c

    82	
    83	/**
    84	 * dcp_crtc_send_page_flip_event - helper to send vblank event after pageflip
    85	 *
    86	 * Compensate for unknown slack between page flip and arrival of the
    87	 * swap_complete callback. Minimal observed duration on DCP with HDMI output
    88	 * was around 2.3 ms. If the fb swap was submitted closer to the expected
    89	 * swap_complete it gets a penalty of one frame duration. This is on the border
    90	 * of unreasonable considering that Apple advertises support for 240 Hz (frame
    91	 * duration of 4.167 ms).
    92	 * It is unreasonable considering kwin's kms commit scheduling. Kwin commits
    93	 * 1.5 ms + the mode's vblank time before the expected next page flip
    94	 * completion. This results in presenting at half the display's rate for HDMI
    95	 * outputs.
    96	 * This might be a difference between dcp and dcpext.
    97	 */
    98	static void dcp_crtc_send_page_flip_event(struct apple_crtc *crtc,
    99						  struct drm_pending_vblank_event *e,
   100						  ktime_t now, ktime_t start)
 > 101	{
   102		struct drm_device *dev = crtc->base.dev;
   103		u64 seq;
   104		unsigned int pipe = drm_crtc_index(&crtc->base);
   105		ktime_t flip;
   106	
   107		seq = 0;
   108		if (start != KTIME_MIN) {
   109			s64 delta = ktime_us_delta(now, start);
   110			if (delta <= 500)
   111				flip = now;
   112			else if (delta >= 2500)
   113				flip = ktime_sub_us(now, 1000);
   114			else
   115				flip = ktime_sub_us(now, (delta - 500) / 2);
   116		} else {
   117			flip = now;
   118		}
   119		e->pipe = pipe;
   120		send_vblank_event(dev, e, seq, flip);
   121	}
   122	

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