Subject: [PATCH v3 14/15] drm/mxsfb: Add support for horizontal stride

From: Robert Chiras <[email-masked]>
Date: Wed, 21 Aug 2019 13:15:54 +0300

Besides the eLCDIF block, there is another IP block, used in the past
for EPDC panels. Since the iMX.8mq doesn't have an EPDC connector, this
block is not documented, but we can use it to do additional operations
on the frame buffer.
In this case, we can use the pigeon registers from this IP block in
order to do horizontal crop on the frame buffer processed by the eLCDIF
block.

Signed-off-by: Robert Chiras <[email-masked]>
---
 drivers/gpu/drm/mxsfb/mxsfb_crtc.c | 79 ++++++++++++++++++++++++++++++++++++--
 drivers/gpu/drm/mxsfb/mxsfb_drv.c  |  1 +
 drivers/gpu/drm/mxsfb/mxsfb_regs.h | 16 ++++++++
 3 files changed, 92 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/mxsfb/mxsfb_crtc.c b/drivers/gpu/drm/mxsfb/mxsfb_crtc.c
index a12f53d..317575e 100644
--- a/drivers/gpu/drm/mxsfb/mxsfb_crtc.c
+++ b/drivers/gpu/drm/mxsfb/mxsfb_crtc.c
@@ -15,6 +15,7 @@
 
 #include <video/videomode.h>
 
+#include <drm/drm_atomic.h>
 #include <drm/drm_atomic_helper.h>
 #include <drm/drm_crtc.h>
 #include <drm/drm_fb_cma_helper.h>
@@ -435,13 +436,66 @@ void mxsfb_crtc_disable(struct mxsfb_drm_private *mxsfb)
 	clk_disable_unprepare(mxsfb->clk_axi);
 }
 
+void mxsfb_set_fb_hcrop(struct mxsfb_drm_private *mxsfb, u32 src_w, u32 fb_w)
+{
+	u32 mask_cnt, htotal, hcount;
+	u32 vdctrl2, vdctrl3, vdctrl4, transfer_count;
+	u32 pigeon_12_0, pigeon_12_1, pigeon_12_2;
+
+	if (src_w == fb_w) {
+		writel(0x0, mxsfb->base + HW_EPDC_PIGEON_12_0);
+		writel(0x0, mxsfb->base + HW_EPDC_PIGEON_12_1);
+
+		return;
+	}
+
+	transfer_count = readl(mxsfb->base + LCDC_V4_TRANSFER_COUNT);
+	hcount = TRANSFER_COUNT_GET_HCOUNT(transfer_count);
+
+	transfer_count &= ~TRANSFER_COUNT_SET_HCOUNT(0xffff);
+	transfer_count |= TRANSFER_COUNT_SET_HCOUNT(fb_w);
+	writel(transfer_count, mxsfb->base + LCDC_V4_TRANSFER_COUNT);
+
+	vdctrl2 = readl(mxsfb->base + LCDC_VDCTRL2);
+	htotal  = VDCTRL2_GET_HSYNC_PERIOD(vdctrl2);
+	htotal  += fb_w - hcount;
+	vdctrl2 &= ~VDCTRL2_SET_HSYNC_PERIOD(0x3ffff);
+	vdctrl2 |= VDCTRL2_SET_HSYNC_PERIOD(htotal);
+	writel(vdctrl2, mxsfb->base + LCDC_VDCTRL2);
+
+	vdctrl4 = readl(mxsfb->base + LCDC_VDCTRL4);
+	vdctrl4 &= ~SET_DOTCLK_H_VALID_DATA_CNT(0x3ffff);
+	vdctrl4 |= SET_DOTCLK_H_VALID_DATA_CNT(fb_w);
+	writel(vdctrl4, mxsfb->base + LCDC_VDCTRL4);
+
+	/* configure related pigeon registers */
+	vdctrl3  = readl(mxsfb->base + LCDC_VDCTRL3);
+	mask_cnt = GET_HOR_WAIT_CNT(vdctrl3) - 5;
+
+	pigeon_12_0 = PIGEON_12_0_SET_STATE_MASK(0x24)		|
+		      PIGEON_12_0_SET_MASK_CNT(mask_cnt)	|
+		      PIGEON_12_0_SET_MASK_CNT_SEL(0x6)		|
+		      PIGEON_12_0_POL_ACTIVE_LOW		|
+		      PIGEON_12_0_EN;
+	writel(pigeon_12_0, mxsfb->base + HW_EPDC_PIGEON_12_0);
+
+	pigeon_12_1 = PIGEON_12_1_SET_CLR_CNT(src_w) |
+		      PIGEON_12_1_SET_SET_CNT(0x0);
+	writel(pigeon_12_1, mxsfb->base + HW_EPDC_PIGEON_12_1);
+
+	pigeon_12_2 = 0x0;
+	writel(pigeon_12_2, mxsfb->base + HW_EPDC_PIGEON_12_2);
+}
+
 void mxsfb_plane_atomic_update(struct mxsfb_drm_private *mxsfb,
 			       struct drm_plane_state *state)
 {
 	struct drm_simple_display_pipe *pipe = &mxsfb->pipe;
 	struct drm_crtc *crtc = &pipe->crtc;
+	struct drm_plane_state *new_state = pipe->plane.state;
+	struct drm_framebuffer *fb = pipe->plane.state->fb;
 	struct drm_pending_vblank_event *event;
-	dma_addr_t paddr;
+	u32 fb_addr, src_off, src_w, stride, cpp = 0;
 
 	spin_lock_irq(&crtc->dev->event_lock);
 	event = crtc->state->event;
@@ -456,10 +510,27 @@ void mxsfb_plane_atomic_update(struct mxsfb_drm_private *mxsfb,
 	}
 	spin_unlock_irq(&crtc->dev->event_lock);
 
-	paddr = mxsfb_get_fb_paddr(mxsfb);
-	if (paddr) {
+	if (!fb)
+		return;
+
+	fb_addr = mxsfb_get_fb_paddr(mxsfb);
+	if (mxsfb->devdata->ipversion >= 4) {
+		cpp = fb->format->cpp[0];
+		src_off = (new_state->src_y >> 16) * fb->pitches[0] +
+			  (new_state->src_x >> 16) * cpp;
+		fb_addr += fb->offsets[0] + src_off;
+	}
+
+	if (fb_addr) {
 		clk_prepare_enable(mxsfb->clk_axi);
-		writel(paddr, mxsfb->base + mxsfb->devdata->next_buf);
+		writel(fb_addr, mxsfb->base + mxsfb->devdata->next_buf);
 		clk_disable_unprepare(mxsfb->clk_axi);
 	}
+
+	if (mxsfb->devdata->ipversion >= 4 &&
+	    unlikely(drm_atomic_crtc_needs_modeset(new_state->crtc->state))) {
+		stride = DIV_ROUND_UP(fb->pitches[0], cpp);
+		src_w = new_state->src_w >> 16;
+		mxsfb_set_fb_hcrop(mxsfb, src_w, stride);
+	}
 }
diff --git a/drivers/gpu/drm/mxsfb/mxsfb_drv.c b/drivers/gpu/drm/mxsfb/mxsfb_drv.c
index dd5809b..c4ce706 100644
--- a/drivers/gpu/drm/mxsfb/mxsfb_drv.c
+++ b/drivers/gpu/drm/mxsfb/mxsfb_drv.c
@@ -136,6 +136,7 @@ static int mxsfb_atomic_helper_check(struct drm_device *dev,
 		if (old_bpp != new_bpp)
 			new_state->mode_changed = true;
 	}
+
 	return ret;
 }
 
diff --git a/drivers/gpu/drm/mxsfb/mxsfb_regs.h b/drivers/gpu/drm/mxsfb/mxsfb_regs.h
index 0f63ba1..df3279b 100644
--- a/drivers/gpu/drm/mxsfb/mxsfb_regs.h
+++ b/drivers/gpu/drm/mxsfb/mxsfb_regs.h
@@ -145,6 +145,22 @@
 #define DEBUG0_HSYNC			BIT(26)
 #define DEBUG0_VSYNC			BIT(25)
 
+/* pigeon registers for crop */
+#define HW_EPDC_PIGEON_12_0		0xb00
+#define HW_EPDC_PIGEON_12_1		0xb10
+#define HW_EPDC_PIGEON_12_2		0xb20
+
+#define PIGEON_12_0_SET_STATE_MASK(x)	REG_PUT((x), 31, 24)
+#define PIGEON_12_0_SET_MASK_CNT(x)	REG_PUT((x), 23, 12)
+#define PIGEON_12_0_SET_MASK_CNT_SEL(x)	REG_PUT((x), 11,  8)
+#define PIGEON_12_0_SET_OFFSET(x)	REG_PUT((x),  7,  4)
+#define PIGEON_12_0_SET_INC_SEL(x)	REG_PUT((x),  3,  2)
+#define PIGEON_12_0_POL_ACTIVE_LOW	BIT(1)
+#define PIGEON_12_0_EN			BIT(0)
+
+#define PIGEON_12_1_SET_CLR_CNT(x)	REG_PUT((x), 31, 16)
+#define PIGEON_12_1_SET_SET_CNT(x)	REG_PUT((x), 15,  0)
+
 #define MXSFB_MIN_XRES			120
 #define MXSFB_MIN_YRES			120
 #define MXSFB_MAX_XRES			0xffff
-- 
2.7.4

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