linux-kernel - [PATCH 8/8] drm/tidss: Enable Dual and Duplicate Modes for OLDI

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Message-ID: <20220719080845.22122-9-a-bhatia1@ti.com>
Date:   Tue, 19 Jul 2022 13:38:45 +0530
From:   Aradhya Bhatia <a-bhatia1@...com>
To:     Tomi Valkeinen <tomba@...nel.org>, Jyri Sarha <jyri.sarha@....fi>,
        Rob Herring <robh+dt@...nel.org>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>
CC:     Darren Etheridge <detheridge@...com>, Nishanth Menon <nm@...com>,
        Vignesh Raghavendra <vigneshr@...com>,
        Rahul T R <r-ravikumar@...com>,
        Krunal Bhargav <k-bhargav@...com>,
        Devarsh Thakkar <devarsht@...com>,
        DRI Development List <dri-devel@...ts.freedesktop.org>,
        Devicetree List <devicetree@...r.kernel.org>,
        Linux Kernel List <linux-kernel@...r.kernel.org>
Subject: [PATCH 8/8] drm/tidss: Enable Dual and Duplicate Modes for OLDI

The AM625 DSS peripheral supports 2 OLDI TXes which can work to enable 2
duplicated displays of smaller resolutions or enable a single Dual-Link
display with a higher resolution (1920x1200).

Configure the necessary register to enable the different modes.

Signed-off-by: Aradhya Bhatia <a-bhatia1@...com>
---
 drivers/gpu/drm/tidss/tidss_dispc.c | 44 +++++++++++++++++++++++++++--
 1 file changed, 41 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/tidss/tidss_dispc.c b/drivers/gpu/drm/tidss/tidss_dispc.c
index 0b9689453ee8..28cb61259471 100644
--- a/drivers/gpu/drm/tidss/tidss_dispc.c
+++ b/drivers/gpu/drm/tidss/tidss_dispc.c
@@ -1021,8 +1021,8 @@ static void dispc_enable_oldi(struct dispc_device *dispc, u32 hw_videoport,
 	int count = 0;
 
 	/*
-	 * For the moment DUALMODESYNC, MASTERSLAVE, MODE, and SRC
-	 * bits of DISPC_VP_DSS_OLDI_CFG are set statically to 0.
+	 * For the moment MASTERSLAVE, and SRC bits of DISPC_VP_DSS_OLDI_CFG are
+	 * set statically to 0.
 	 */
 
 	if (fmt->data_width == 24)
@@ -1039,7 +1039,45 @@ static void dispc_enable_oldi(struct dispc_device *dispc, u32 hw_videoport,
 
 	oldi_cfg |= BIT(0); /* ENABLE */
 
-	dispc_vp_write(dispc, hw_videoport, DISPC_VP_DSS_OLDI_CFG, oldi_cfg);
+	/*
+	 * As per all the current implementations of DSS, the OLDI TXes are present only on
+	 * hw_videoport = 0 (OLDI TX 0). However, the config register for 2nd OLDI TX (OLDI TX 1)
+	 * is present in the address space of hw_videoport = 1. Hence, using "hw_videoport + 1" to
+	 * configure OLDI TX 1.
+	 */
+
+	switch (dispc->oldi_mode) {
+	case OLDI_MODE_OFF:
+		oldi_cfg &= ~BIT(0); /* DISABLE */
+		dispc_vp_write(dispc, hw_videoport, DISPC_VP_DSS_OLDI_CFG, oldi_cfg);
+		dispc_vp_write(dispc, hw_videoport + 1, DISPC_VP_DSS_OLDI_CFG, oldi_cfg);
+		break;
+
+	case OLDI_SINGLE_LINK_SINGLE_MODE_0:
+		dispc_vp_write(dispc, hw_videoport, DISPC_VP_DSS_OLDI_CFG, oldi_cfg);
+		break;
+
+	case OLDI_SINGLE_LINK_SINGLE_MODE_1:
+		dispc_vp_write(dispc, hw_videoport + 1, DISPC_VP_DSS_OLDI_CFG, oldi_cfg);
+		break;
+
+	case OLDI_SINGLE_LINK_DUPLICATE_MODE:
+		oldi_cfg |= BIT(5); /* DUPLICATE MODE */
+		dispc_vp_write(dispc, hw_videoport, DISPC_VP_DSS_OLDI_CFG, oldi_cfg);
+		dispc_vp_write(dispc, hw_videoport + 1, DISPC_VP_DSS_OLDI_CFG, oldi_cfg);
+		break;
+
+	case OLDI_DUAL_LINK:
+		oldi_cfg |= BIT(11); /* DUALMODESYNC */
+		dispc_vp_write(dispc, hw_videoport, DISPC_VP_DSS_OLDI_CFG, oldi_cfg);
+		dispc_vp_write(dispc, hw_videoport + 1, DISPC_VP_DSS_OLDI_CFG, oldi_cfg);
+		break;
+
+	default:
+		dev_warn(dispc->dev, "%s: Incorrect oldi mode. Returning.\n",
+			 __func__);
+		return;
+	}
 
 	while (!(oldi_reset_bit & dispc_read(dispc, DSS_SYSSTATUS)) &&
 	       count < 10000)
-- 
2.37.0