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Commit 54da691d authored by Thomas Gummerer's avatar Thomas Gummerer Committed by Jani Nikula
Browse files

drm/i915: fix screen flickering 



Commit c9f038a1 ("drm/i915: Don't assume primary & cursor are
always on for wm calculation (v4)") fixes a null pointer dereference.
Setting the primary and cursor panes to false in
ilk_compute_wm_parameters to false does however give the following
errors in the kernel log and causes the screen to flicker.

[  101.133716] [drm:intel_set_cpu_fifo_underrun_reporting [i915]]
*ERROR* uncleared fifo underrun on pipe A
[  101.133725] [drm:intel_cpu_fifo_underrun_irq_handler [i915]]
*ERROR* CPU pipe A FIFO underrun

Always setting the panes to enabled fixes this error.

Helped-by: default avatarMatt Roper <matthew.d.roper@intel.com>
Signed-off-by: default avatarThomas Gummerer <t.gummerer@gmail.com>
Reviewed-by: default avatarMatt Roper <matthew.d.roper@intel.com>
Tested-by: default avatarMario Kleiner <mario.kleiner.de@gmail.com>
Signed-off-by: default avatarJani Nikula <jani.nikula@intel.com>
parent e2608180

drivers/gpu/drm/i915/intel_pm.c

+11 −13
Original line number Original line Diff line number Diff line
@@ -2045,22 +2045,20 @@ static void ilk_compute_wm_parameters(struct drm_crtc *crtc, 
	p->pipe_htotal = intel_crtc->config->base.adjusted_mode.crtc_htotal;

	p->pipe_htotal = intel_crtc->config->base.adjusted_mode.crtc_htotal;

	p->pixel_rate = ilk_pipe_pixel_rate(dev, crtc);

	p->pixel_rate = ilk_pipe_pixel_rate(dev, crtc);





	if (crtc->primary->state->fb) {

	if (crtc->primary->state->fb)

		p->pri.enabled = true;

		p->pri.bytes_per_pixel =

		p->pri.bytes_per_pixel =

			crtc->primary->state->fb->bits_per_pixel / 8;

			crtc->primary->state->fb->bits_per_pixel / 8;

	} else {

	else

		p->pri.enabled = false;

		p->pri.bytes_per_pixel = 4;

		p->pri.bytes_per_pixel = 0;

	}





	if (crtc->cursor->state->fb) {

		p->cur.enabled = true;

	p->cur.bytes_per_pixel = 4;

	p->cur.bytes_per_pixel = 4;

	} else {

	/*

		p->cur.enabled = false;

	 * TODO: for now, assume primary and cursor planes are always enabled.

		p->cur.bytes_per_pixel = 0;

	 * Setting them to false makes the screen flicker.

	}

	 */

	p->pri.enabled = true;

	p->cur.enabled = true;



	p->pri.horiz_pixels = intel_crtc->config->pipe_src_w;

	p->pri.horiz_pixels = intel_crtc->config->pipe_src_w;

	p->cur.horiz_pixels = intel_crtc->base.cursor->state->crtc_w;

	p->cur.horiz_pixels = intel_crtc->base.cursor->state->crtc_w;