target/linux/bcm27xx/patches-5.4/950-0860-drm-vc4-FKMS-Block-modes-with-odd-horizontal-timing-.patch

From aa791f2cb6777e8ca99102009b631afdeea1c59d Mon Sep 17 00:00:00 2001
From: Dave Stevenson <dave.stevenson@raspberrypi.com>
Date: Fri, 3 Jul 2020 16:06:55 +0100
Subject: [PATCH] drm/vc4: FKMS Block modes with odd horizontal
 timing values on Pi4

Pi4 HDMI pipeline is 2 pixels/clock and can not produce timings
that have odd values for active pixels, front porch, sync width,
or back porch.
Detect these modes and block them within fkms.

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
---
 drivers/gpu/drm/vc4/vc4_firmware_kms.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

--- a/drivers/gpu/drm/vc4/vc4_firmware_kms.c
+++ b/drivers/gpu/drm/vc4/vc4_firmware_kms.c
@@ -44,6 +44,7 @@ struct get_display_cfg {
 
 struct vc4_fkms {
 	struct get_display_cfg cfg;
+	bool bcm2711;
 };
 
 #define PLANES_PER_CRTC		3
@@ -1097,6 +1098,17 @@ vc4_crtc_mode_valid(struct drm_crtc *crt
 		break;
 	}
 
+	/* Pi4 can't generate odd horizontal timings on HDMI, so reject modes
+	 * that would set them.
+	 */
+	if (fkms->bcm2711 &&
+	    (vc4_crtc->display_number == 2 || vc4_crtc->display_number == 7) &&
+	    ((mode->hdisplay |				/* active */
+	      (mode->hsync_start - mode->hdisplay) |	/* front porch */
+	      (mode->hsync_end - mode->hsync_start) |	/* sync pulse */
+	      (mode->htotal - mode->hsync_end)) & 1))	/* back porch */
+		return MODE_H_ILLEGAL;
+
 	return MODE_OK;
 }
 
@@ -1282,6 +1294,8 @@ static const struct drm_crtc_helper_func
 
 static const struct of_device_id vc4_firmware_kms_dt_match[] = {
 	{ .compatible = "raspberrypi,rpi-firmware-kms" },
+	{ .compatible = "raspberrypi,rpi-firmware-kms-2711",
+	  .data = (void *)1 },
 	{}
 };
 
@@ -1815,6 +1829,7 @@ static int vc4_fkms_bind(struct device *
 	struct drm_device *drm = dev_get_drvdata(master);
 	struct vc4_dev *vc4 = to_vc4_dev(drm);
 	struct device_node *firmware_node;
+	const struct of_device_id *match;
 	struct vc4_crtc **crtc_list;
 	u32 num_displays, display_num;
 	struct vc4_fkms *fkms;
@@ -1827,6 +1842,12 @@ static int vc4_fkms_bind(struct device *
 	if (!fkms)
 		return -ENOMEM;
 
+	match = of_match_device(vc4_firmware_kms_dt_match, dev);
+	if (!match)
+		return -ENODEV;
+	if (match->data)
+		fkms->bcm2711 = true;
+
 	/* firmware kms doesn't have precise a scanoutpos implementation, so
 	 * we can't do the precise vblank timestamp mode.
 	 */