linux-kernel - [PATCH 28/29] drm/tidss: encoder: implement get_current

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Message-Id: <20250902-drm-state-readout-v1-28-14ad5315da3f@kernel.org>
Date: Tue, 02 Sep 2025 10:32:56 +0200
From: Maxime Ripard <mripard@...nel.org>
To: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
 Thomas Zimmermann <tzimmermann@...e.de>, David Airlie <airlied@...il.com>, 
 Simona Vetter <simona@...ll.ch>, Andrzej Hajda <andrzej.hajda@...el.com>, 
 Neil Armstrong <neil.armstrong@...aro.org>, Robert Foss <rfoss@...nel.org>, 
 Laurent Pinchart <Laurent.pinchart@...asonboard.com>, 
 Jonas Karlman <jonas@...boo.se>, Jernej Skrabec <jernej.skrabec@...il.com>, 
 Jyri Sarha <jyri.sarha@....fi>, 
 Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
Cc: Devarsh Thakkar <devarsht@...com>, dri-devel@...ts.freedesktop.org, 
 linux-kernel@...r.kernel.org, Maxime Ripard <mripard@...nel.org>
Subject: [PATCH 28/29] drm/tidss: encoder: implement get_current_crtc

The tidss driver doesn't really care implement anything with encoders,
it just relies on simple encoders, bridges and drm_bridge_connector.

In order to figure out the CRTC -> connector association from the
hardware state, we do need encoder support though, through the
get_current_crtc callback.

Since the tidss encoders are always connected to a single CRTC, we don't
really need to read the hardware state though, we can simply return the
one we know we are always connected to.

Signed-off-by: Maxime Ripard <mripard@...nel.org>
---
 drivers/gpu/drm/tidss/tidss_encoder.c | 24 ++++++++++++++++++++++--
 1 file changed, 22 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/tidss/tidss_encoder.c b/drivers/gpu/drm/tidss/tidss_encoder.c
index 81a04f7677701b0b1bee204ac9fc5835ac373950..2cb12ab48a48cec453defcb261915e4663806289 100644
--- a/drivers/gpu/drm/tidss/tidss_encoder.c
+++ b/drivers/gpu/drm/tidss/tidss_encoder.c
@@ -79,10 +79,29 @@ static const struct drm_bridge_funcs tidss_bridge_funcs = {
 	.atomic_reset			= drm_atomic_helper_bridge_reset,
 	.atomic_duplicate_state		= drm_atomic_helper_bridge_duplicate_state,
 	.atomic_destroy_state		= drm_atomic_helper_bridge_destroy_state,
 };
 
+static struct drm_crtc *tidss_encoder_get_current_crtc(struct drm_encoder *encoder)
+{
+	struct drm_crtc *crtc;
+
+	WARN_ON(hweight32(encoder->possible_crtcs) > 1);
+
+	drm_for_each_crtc(crtc, encoder->dev) {
+		if (encoder->possible_crtcs == (1 << drm_crtc_index(crtc)))
+		    return crtc;
+	}
+
+	return NULL;
+}
+
+static const struct drm_encoder_funcs tidss_encoder_funcs = {
+	.get_current_crtc = tidss_encoder_get_current_crtc,
+	.destroy = drm_encoder_cleanup,
+};
+
 int tidss_encoder_create(struct tidss_device *tidss,
 			 struct drm_bridge *next_bridge,
 			 u32 encoder_type, u32 possible_crtcs)
 {
 	struct tidss_encoder *t_enc;
@@ -93,12 +112,13 @@ int tidss_encoder_create(struct tidss_device *tidss,
 	t_enc = devm_drm_bridge_alloc(tidss->dev, struct tidss_encoder,
 				      bridge, &tidss_bridge_funcs);
 	if (IS_ERR(t_enc))
 		return PTR_ERR(t_enc);
 
-	ret = drm_simple_encoder_init(&tidss->ddev, &t_enc->encoder,
-				      encoder_type);
+	ret = drm_encoder_init(&tidss->ddev, &t_enc->encoder,
+			       &tidss_encoder_funcs,
+			       encoder_type, NULL);
 	if (ret)
 		return ret;
 
 	t_enc->tidss = tidss;
 	t_enc->next_bridge = next_bridge;

-- 
2.50.1