drm: kirin: Revert "Fix for hikey620 display offset problem"

This reverts commit ff57c651.

With the commit ff57c651 ("drm: kirin: Fix for hikey620
display offset problem") we added support for handling LDI
overflows by resetting the hardware.

However, its been observed that when we do hit the LDI overflow
condition, the irq seems to be screaming, and we do nothing but
stream:
  [drm:ade_irq_handler [kirin_drm]] *ERROR* LDI underflow!
over and over to the screen

I've tried a few appraoches to avoid this, but none has yet
been successful and the cure here is worse then the original
disease, so revert this for now.

Cc: Xinliang Liu <xinliang.liu@linaro.org>
Cc: Rongrong Zou <zourongrong@gmail.com>
Cc: Xinwei Kong <kong.kongxinwei@hisilicon.com>
Cc: Chen Feng <puck.chen@hisilicon.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: dri-devel <dri-devel@lists.freedesktop.org>
Fixes: ff57c651 ("drm: kirin: Fix for hikey620 display offset problem")
Signed-off-by: John Stultz <john.stultz@linaro.org>
Acked-by: Xinliang Liu <xinliang.liu@linaro.org>
Signed-off-by: Xinliang Liu <xinliang.liu@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20200303163228.52741-1-john.stultz@linaro.org

drivers/gpu/drm/hisilicon/kirin/kirin_ade_reg.h

@@ -83,7 +83,6 @@
 #define VSIZE_OFST			20
 #define LDI_INT_EN			0x741C
 #define FRAME_END_INT_EN_OFST		1
-#define UNDERFLOW_INT_EN_OFST		2
 #define LDI_CTRL			0x7420
 #define BPP_OFST			3
 #define DATA_GATE_EN			BIT(2)

drivers/gpu/drm/hisilicon/kirin/kirin_drm_ade.c

@@ -46,7 +46,6 @@ struct ade_hw_ctx {
 	struct clk *media_noc_clk;
 	struct clk *ade_pix_clk;
 	struct reset_control *reset;
-	struct work_struct display_reset_wq;
 	bool power_on;
 	int irq;
 
@@ -136,7 +135,6 @@ static void ade_init(struct ade_hw_ctx *ctx)
 	 */
 	ade_update_bits(base + ADE_CTRL, FRM_END_START_OFST,
 			FRM_END_START_MASK, REG_EFFECTIVE_IN_ADEEN_FRMEND);
-	ade_update_bits(base + LDI_INT_EN, UNDERFLOW_INT_EN_OFST, MASK(1), 1);
 }
 
 static bool ade_crtc_mode_fixup(struct drm_crtc *crtc,
@@ -304,17 +302,6 @@ static void ade_crtc_disable_vblank(struct drm_crtc *crtc)
 			MASK(1), 0);
 }
 
-static void drm_underflow_wq(struct work_struct *work)
-{
-	struct ade_hw_ctx *ctx = container_of(work, struct ade_hw_ctx,
-					      display_reset_wq);
-	struct drm_device *drm_dev = ctx->crtc->dev;
-	struct drm_atomic_state *state;
-
-	state = drm_atomic_helper_suspend(drm_dev);
-	drm_atomic_helper_resume(drm_dev, state);
-}
-
 static irqreturn_t ade_irq_handler(int irq, void *data)
 {
 	struct ade_hw_ctx *ctx = data;
@@ -331,12 +318,6 @@ static irqreturn_t ade_irq_handler(int irq, void *data)
 				MASK(1), 1);
 		drm_crtc_handle_vblank(crtc);
 	}
-	if (status & BIT(UNDERFLOW_INT_EN_OFST)) {
-		ade_update_bits(base + LDI_INT_CLR, UNDERFLOW_INT_EN_OFST,
-				MASK(1), 1);
-		DRM_ERROR("LDI underflow!");
-		schedule_work(&ctx->display_reset_wq);
-	}
 
 	return IRQ_HANDLED;
 }
@@ -919,7 +900,6 @@ static void *ade_hw_ctx_alloc(struct platform_device *pdev,
 	if (ret)
 		return ERR_PTR(-EIO);
 
-	INIT_WORK(&ctx->display_reset_wq, drm_underflow_wq);
 	ctx->crtc = crtc;
 
 	return ctx;