linux-kernel - [PATCH 4/4] drm/tidss: Fix sampling edge configuration

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Message-Id: <20250730-fix-edge-handling-v1-4-1bdfb3fe7922@bootlin.com>
Date: Wed, 30 Jul 2025 19:02:47 +0200
From: Louis Chauvet <louis.chauvet@...tlin.com>
To: Jyri Sarha <jyri.sarha@....fi>, 
 Tomi Valkeinen <tomi.valkeinen@...asonboard.com>, 
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, 
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, 
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>, Sam Ravnborg <sam@...nborg.org>, 
 Benoit Parrot <bparrot@...com>, Lee Jones <lee@...nel.org>, 
 Nishanth Menon <nm@...com>, Vignesh Raghavendra <vigneshr@...com>, 
 Tero Kristo <kristo@...nel.org>
Cc: thomas.petazzoni@...tlin.com, Jyri Sarha <jsarha@...com>, 
 Tomi Valkeinen <tomi.valkeinen@...com>, dri-devel@...ts.freedesktop.org, 
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, 
 linux-arm-kernel@...ts.infradead.org, stable@...r.kernel.org, 
 Louis Chauvet <louis.chauvet@...tlin.com>
Subject: [PATCH 4/4] drm/tidss: Fix sampling edge configuration

As stated in the AM62x Technical Reference Manual (SPRUIV7B), the data
sampling edge needs to be configured in two distinct registers: one in the
TIDSS IP and another in the memory-mapped control register modules. Since
the latter is not within the same address range, a phandle to a syscon
device is used to access the regmap.

Fixes: 32a1795f57ee ("drm/tidss: New driver for TI Keystone platform Display SubSystem")
Signed-off-by: Louis Chauvet <louis.chauvet@...tlin.com>

---

Cc: stable@...r.kernel.org
---
 drivers/gpu/drm/tidss/tidss_dispc.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/drivers/gpu/drm/tidss/tidss_dispc.c b/drivers/gpu/drm/tidss/tidss_dispc.c
index c0277fa36425ee1f966dccecf2b69a2d01794899..65ca7629a2e75437023bf58f8a1bddc24db5e3da 100644
--- a/drivers/gpu/drm/tidss/tidss_dispc.c
+++ b/drivers/gpu/drm/tidss/tidss_dispc.c
@@ -498,6 +498,7 @@ struct dispc_device {
 	const struct dispc_features *feat;
 
 	struct clk *fclk;
+	struct regmap *clk_ctrl;
 
 	bool is_enabled;
 
@@ -1267,6 +1268,11 @@ void dispc_vp_enable(struct dispc_device *dispc, u32 hw_videoport,
 		       FLD_VAL(mode->vdisplay - 1, 27, 16));
 
 	VP_REG_FLD_MOD(dispc, hw_videoport, DISPC_VP_CONTROL, 1, 0, 0);
+
+	if (dispc->clk_ctrl) {
+		regmap_update_bits(dispc->clk_ctrl, 0, 0x100, ipc ? 0x100 : 0x000);
+		regmap_update_bits(dispc->clk_ctrl, 0, 0x200, rf ? 0x200 : 0x000);
+	}
 }
 
 void dispc_vp_disable(struct dispc_device *dispc, u32 hw_videoport)
@@ -3012,6 +3018,14 @@ int dispc_init(struct tidss_device *tidss)
 
 	dispc_init_errata(dispc);
 
+	dispc->clk_ctrl = syscon_regmap_lookup_by_phandle_optional(tidss->dev->of_node,
+								   "ti,clk-ctrl");
+	if (IS_ERR(dispc->clk_ctrl)) {
+		r = dev_err_probe(dispc->dev, PTR_ERR(dispc->clk_ctrl),
+				  "DISPC: syscon_regmap_lookup_by_phandle failed.\n");
+		return r;
+	}
+
 	dispc->fourccs = devm_kcalloc(dev, ARRAY_SIZE(dispc_color_formats),
 				      sizeof(*dispc->fourccs), GFP_KERNEL);
 	if (!dispc->fourccs)

-- 
2.50.1