[PATCH 14/15] drm/i915: skl nv12 wa - NV12 to RGB switch

Chandra Konduru
2015-09-05T02:35:11Z

Switching format from NV12 to RGB can result in display underrun
and corruption. This workaround sets bits 15 & 19 to 1 in
CLKGATE_DIS_PSL register to address transition underrun.

Signed-off-by: Chandra Konduru <chandra.konduru@intel.com>
---
drivers/gpu/drm/i915/i915_reg.h | 8 ++++++++
drivers/gpu/drm/i915/intel_display.c | 25 +++++++++++++++++++++++++
2 files changed, 33 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index d20f235..2e2636d 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -5366,6 +5366,14 @@ enum skl_disp_power_wells {
#define CHICKEN_DCPR_1 0x46430
#define IDLE_WAKEMEM_MASK (1 << 13)

+#define CLKGATE_DIS_PSL_A 0x46520
+#define CLKGATE_DIS_PSL_B 0x46524
+#define CLKGATE_DIS_PSL_C 0x46528
+#define DUPS1_GATING_DIS (1 << 15)
+#define DUPS2_GATING_DIS (1 << 19)
+#define DUPS3_GATING_DIS (1 << 23)
+#define CLKGATE_DIS_PSL(pipe) _PIPE(pipe, CLKGATE_DIS_PSL_A, CLKGATE_DIS_PSL_B)
+
/* SKL new cursor registers */
#define _CUR_BUF_CFG_A 0x7017c
#define _CUR_BUF_CFG_B 0x7117c
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 9e11439..457b79b 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -5017,6 +5017,25 @@ static bool hsw_crtc_supports_ips(struct intel_crtc *crtc)
return HAS_IPS(crtc->base.dev) && crtc->pipe == PIPE_A;
}

+/*
+ * Switching format from NV12 to RGB can result in display underrun
+ * and corruption. Workaround is to set bits 15 & 19 to 1 in
+ * CLKGATE_DIS_PSL register.
+ */
+static void skl_wa_clkgate(struct drm_i915_private *dev_priv,
+ int pipe, int enable)
+{
+ if (pipe == PIPE_A || pipe == PIPE_B) {
+ if (enable)
+ I915_WRITE(CLKGATE_DIS_PSL(pipe),
+ DUPS1_GATING_DIS | DUPS2_GATING_DIS);
+ else
+ I915_WRITE(CLKGATE_DIS_PSL(pipe),
+ I915_READ(CLKGATE_DIS_PSL(pipe) &
+ ~(DUPS1_GATING_DIS|DUPS2_GATING_DIS)));
+ }
+}
+
static void haswell_crtc_enable(struct drm_crtc *crtc)
{
struct drm_device *dev = crtc->dev;
@@ -5107,6 +5126,9 @@ static void haswell_crtc_enable(struct drm_crtc *crtc)
intel_wait_for_vblank(dev, hsw_workaround_pipe);
intel_wait_for_vblank(dev, hsw_workaround_pipe);
}
+
+ /* workaround for NV12 */
+ skl_wa_clkgate(dev_priv, pipe, 1);
}

static void ironlake_pfit_disable(struct intel_crtc *crtc)
@@ -5224,6 +5246,9 @@ static void haswell_crtc_disable(struct drm_crtc *crtc)

intel_crtc->active = false;
intel_update_watermarks(crtc);
+
+ /* workaround for NV12 */
+ skl_wa_clkgate(dev_priv, intel_crtc->pipe, 0);
}

static void i9xx_pfit_enable(struct intel_crtc *crtc)
--
1.7.9.5