linux-kernel - [PATCH v4 15/26] drm/sun4i: sun6i_mipi_dsi: Set proper vblk timing calculation

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20181113111633.20189-16-jagan@amarulasolutions.com>
Date:   Tue, 13 Nov 2018 16:46:22 +0530
From:   Jagan Teki <jagan@...rulasolutions.com>
To:     Maxime Ripard <maxime.ripard@...tlin.com>,
        Chen-Yu Tsai <wens@...e.org>, Icenowy Zheng <icenowy@...c.io>,
        Jernej Skrabec <jernej.skrabec@...l.net>,
        Vasily Khoruzhick <anarsoul@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        David Airlie <airlied@...ux.ie>,
        dri-devel@...ts.freedesktop.org,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>, linux-clk@...r.kernel.org,
        Michael Trimarchi <michael@...rulasolutions.com>,
        linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-sunxi@...glegroups.com,
        linux-amarula@...rulasolutions.com
Cc:     Jagan Teki <jagan@...rulasolutions.com>
Subject: [PATCH v4 15/26] drm/sun4i: sun6i_mipi_dsi: Set proper vblk timing calculation

Unlike hblk, the vblk timings should follow an equation to compute
the desired value for lane 4 devices and rest of devices it would be 0.

BSP code from BPI-M64-bsp is computing vblk as for 4-lane devices
(from linux-sunxi
drivers/video/sunxi/disp2/disp/de/lowlevel_sun50iw1/de_dsi.c)

tmp = (ht*dsi_pixel_bits[format]/8)*vt-(4+dsi_hblk+2);
dsi_vblk = (lane-tmp%lane);

So, update the vblk timing calculation accordingly.

Tested on 2-lane, 4-lane MIPI-DSI LCD panels.

Signed-off-by: Jagan Teki <jagan@...rulasolutions.com>
---
 drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c | 32 ++++++++++++++++++++------
 1 file changed, 25 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
index 63b924b89bd7..703722f7c81b 100644
--- a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
+++ b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
@@ -355,6 +355,30 @@ static void sun6i_dsi_inst_init(struct sun6i_dsi *dsi,
 		     SUN6I_DSI_INST_JUMP_CFG_NUM(1));
 };
 
+static u16 sun6i_dsi_get_timings_vblk(struct sun6i_dsi *dsi,
+				      struct drm_display_mode *mode, u16 hblk)
+{
+	struct mipi_dsi_device *device = dsi->device;
+	u16 vblk = 0;
+
+	/*
+	 * The vertical blank is set using a blanking packet (4 bytes +
+	 * payload + 2 bytes). Its minimal size is therefore 6 bytes
+	 */
+#define VBLK_PACKET_OVERHEAD	6
+	if (device->lanes == 4) {
+		unsigned int Bpp;
+		int tmp;
+
+		Bpp = mipi_dsi_pixel_format_to_bpp(device->format) / 8;
+		tmp = (mode->htotal * Bpp) * mode->vtotal -
+		      (hblk + VBLK_PACKET_OVERHEAD);
+		vblk = (device->lanes - tmp % device->lanes);
+	}
+
+	return vblk;
+}
+
 static u16 sun6i_dsi_get_video_start_delay(struct sun6i_dsi *dsi,
 					   struct drm_display_mode *mode)
 {
@@ -503,13 +527,7 @@ static void sun6i_dsi_setup_timings(struct sun6i_dsi *dsi,
 		   (mode->htotal - (mode->hsync_end - mode->hsync_start)) *
 		   Bpp - HBLK_PACKET_OVERHEAD);
 
-	/*
-	 * And I'm not entirely sure what vblk is about. The driver in
-	 * Allwinner BSP is using a rather convoluted calculation
-	 * there only for 4 lanes. However, using 0 (the !4 lanes
-	 * case) even with a 4 lanes screen seems to work...
-	 */
-	vblk = 0;
+	vblk = sun6i_dsi_get_timings_vblk(dsi, mode, hblk);
 
 	/* How many bytes do we need to send all payloads? */
 	bytes = max_t(size_t, max(max(hfp, hblk), max(hsa, hbp)), vblk);
-- 
2.18.0.321.gffc6fa0e3