Commit facd619b authored by Ville Syrjälä's avatar Ville Syrjälä Committed by Daniel Vetter
Browse files

drm/i915: Fix LP1+ watermark disabling ILK 



On ILK disabling LP1+ watermarks must be done carefully to avoid
underruns. If we just write 0 to the register in the middle of the scan
cycle we often get an underrun. So instead we have to leave the actual
watermark levels in the register intact, and just toggle the enable bit.

Presumably the hardware takes a while to get out of low power mode, and
so the watermark level need to stay valid until that time.

We also have to be careful with the WM1S_LP_EN bit. It seems the
hardware more or less treats it like the actual watermarks numbers, and
so we must not toggle it too soon. Just leave it alone when disabling
the LP1+ watermarks.

Signed-off-by: default avatarVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: default avatarImre Deak <imre.deak@intel.com>
Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
parent 6cef2b8a

drivers/gpu/drm/i915/intel_pm.c

+20 −13
Original line number Diff line number Diff line
@@ -2896,16 +2896,23 @@ static void hsw_write_wm_values(struct drm_i915_private *dev_priv, 
	if (!dirty)

		return;



	if (dirty & WM_DIRTY_LP(3) && previous->wm_lp[2] != 0)

		I915_WRITE(WM3_LP_ILK, 0);

	if (dirty & WM_DIRTY_LP(2) && previous->wm_lp[1] != 0)

		I915_WRITE(WM2_LP_ILK, 0);

	if (dirty & WM_DIRTY_LP(1) && previous->wm_lp[0] != 0)

		I915_WRITE(WM1_LP_ILK, 0);

	if (dirty & WM_DIRTY_LP(3) && previous->wm_lp[2] & WM1_LP_SR_EN) {

		previous->wm_lp[2] &= ~WM1_LP_SR_EN;

		I915_WRITE(WM3_LP_ILK, previous->wm_lp[2]);

	}

	if (dirty & WM_DIRTY_LP(2) && previous->wm_lp[1] & WM1_LP_SR_EN) {

		previous->wm_lp[1] &= ~WM1_LP_SR_EN;

		I915_WRITE(WM2_LP_ILK, previous->wm_lp[1]);

	}

	if (dirty & WM_DIRTY_LP(1) && previous->wm_lp[0] & WM1_LP_SR_EN) {

		previous->wm_lp[0] &= ~WM1_LP_SR_EN;

		I915_WRITE(WM1_LP_ILK, previous->wm_lp[0]);

	}



	if (INTEL_INFO(dev)->gen <= 6 &&

	    dirty & WM_DIRTY_LP(1) && previous->wm_lp_spr[0] != 0)

		I915_WRITE(WM1S_LP_ILK, 0);

	/*

	 * Don't touch WM1S_LP_EN here.

	 * Doing so could cause underruns.

	 */



	if (dirty & WM_DIRTY_PIPE(PIPE_A))

		I915_WRITE(WM0_PIPEA_ILK, results->wm_pipe[0]);
@@ -2949,7 +2956,7 @@ static void hsw_write_wm_values(struct drm_i915_private *dev_priv, 
	}



	if (INTEL_INFO(dev)->gen <= 6) {

		if (dirty & WM_DIRTY_LP(1) && results->wm_lp_spr[0] != 0)

		if (dirty & WM_DIRTY_LP(1) && previous->wm_lp_spr[0] != results->wm_lp_spr[0])

			I915_WRITE(WM1S_LP_ILK, results->wm_lp_spr[0]);

	} else {

		if (dirty & WM_DIRTY_LP(1) && previous->wm_lp_spr[0] != results->wm_lp_spr[0])
@@ -2960,11 +2967,11 @@ static void hsw_write_wm_values(struct drm_i915_private *dev_priv, 
			I915_WRITE(WM3S_LP_IVB, results->wm_lp_spr[2]);

	}



	if (dirty & WM_DIRTY_LP(1) && results->wm_lp[0] != 0)

	if (dirty & WM_DIRTY_LP(1) && previous->wm_lp[0] != results->wm_lp[0])

		I915_WRITE(WM1_LP_ILK, results->wm_lp[0]);

	if (dirty & WM_DIRTY_LP(2) && results->wm_lp[1] != 0)

	if (dirty & WM_DIRTY_LP(2) && previous->wm_lp[1] != results->wm_lp[1])

		I915_WRITE(WM2_LP_ILK, results->wm_lp[1]);

	if (dirty & WM_DIRTY_LP(3) && results->wm_lp[2] != 0)

	if (dirty & WM_DIRTY_LP(3) && previous->wm_lp[2] != results->wm_lp[2])

		I915_WRITE(WM3_LP_ILK, results->wm_lp[2]);



	dev_priv->wm.hw = *results;

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