linux-kernel - [PATCH v8 01/10] drm/sun4i: sun6i_mipi_dsi: Compute burst mode loop N1 instruction delay

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Date:   Fri, 15 Feb 2019 01:02:28 +0530
From:   Jagan Teki <jagan@...rulasolutions.com>
To:     Maxime Ripard <maxime.ripard@...tlin.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>, Chen-Yu Tsai <wens@...e.org>
Cc:     dri-devel@...ts.freedesktop.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-amarula@...rulasolutions.com,
        Michael Trimarchi <michael@...rulasolutions.com>,
        Jagan Teki <jagan@...rulasolutions.com>
Subject: [PATCH v8 01/10] drm/sun4i: sun6i_mipi_dsi: Compute burst mode loop N1 instruction delay

Loop N1 instruction delay varies between burst and non-burst video modes.

1) for burst mode panels it is computed based on the panel pixel clock
   along with horizontal sync and porch timings.
2) for non-burst mode panels, it is same as existing (50 - 1)

Reference code is available in BSP (from linux-sunxi
drivers/video/sunxi/disp2/disp/de/lowlevel_sun50iw1/de_dsi.c)

dsi_dev[sel]->dsi_inst_loop_num.bits.loop_n1=
(panel->lcd_ht-panel->lcd_x)*(150)/(panel->lcd_dclk_freq*8) - 50;
=> (((mode->htotal - mode->hdisplay) * 150) /
     ((mode->clock / 1000) * 8)) - 50;

This patch add loop N1 computation for burst mode by simplifying
existing code to support all possible modes.

Signed-off-by: Jagan Teki <jagan@...rulasolutions.com>
Tested-by: Merlijn Wajer <merlijn@...zup.org>
---
 drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
index 3a28d70dbdc1..8184fbcfd9fd 100644
--- a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
+++ b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
@@ -355,6 +355,24 @@ static void sun6i_dsi_inst_init(struct sun6i_dsi *dsi,
 		     SUN6I_DSI_INST_JUMP_CFG_NUM(1));
 };
 
+static u16 sun6i_dsi_setup_inst_delay(struct sun6i_dsi *dsi,
+				      struct drm_display_mode *mode)
+{
+	struct mipi_dsi_device *device = dsi->device;
+	u32 hsync_porch, dclk;
+	u16 delay;
+
+	hsync_porch = (mode->htotal - mode->hdisplay);
+	dclk = (mode->clock / 1000);
+
+	if (device->mode_flags & MIPI_DSI_MODE_VIDEO_BURST)
+		delay = ((hsync_porch * 150) / (dclk * 8)) - 50;
+	else
+		delay = 50 - 1;
+
+	return delay;
+}
+
 static u16 sun6i_dsi_get_video_start_delay(struct sun6i_dsi *dsi,
 					   struct drm_display_mode *mode)
 {
@@ -401,7 +419,7 @@ static void sun6i_dsi_setup_burst(struct sun6i_dsi *dsi,
 static void sun6i_dsi_setup_inst_loop(struct sun6i_dsi *dsi,
 				      struct drm_display_mode *mode)
 {
-	u16 delay = 50 - 1;
+	u16 delay = sun6i_dsi_setup_inst_delay(dsi, mode);
 
 	regmap_write(dsi->regs, SUN6I_DSI_INST_LOOP_NUM_REG(0),
 		     SUN6I_DSI_INST_LOOP_NUM_N0(50 - 1) |
-- 
2.18.0.321.gffc6fa0e3