linux-kernel - [PATCH v2 2/4] gpu/drm: tegra: dsi: move prepare function at the top of encoder enable

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Message-ID: <20250906131655.239340-3-clamor95@gmail.com>
Date: Sat,  6 Sep 2025 16:16:53 +0300
From: Svyatoslav Ryhel <clamor95@...il.com>
To: Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Thierry Reding <thierry.reding@...il.com>,
	Thierry Reding <treding@...dia.com>,
	Jonathan Hunter <jonathanh@...dia.com>,
	Prashant Gaikwad <pgaikwad@...dia.com>,
	Michael Turquette <mturquette@...libre.com>,
	Stephen Boyd <sboyd@...nel.org>,
	Mikko Perttunen <mperttunen@...dia.com>,
	David Airlie <airlied@...il.com>,
	Simona Vetter <simona@...ll.ch>,
	Svyatoslav Ryhel <clamor95@...il.com>,
	Dmitry Osipenko <digetx@...il.com>,
	Charan Pedumuru <charan.pedumuru@...il.com>
Cc: devicetree@...r.kernel.org,
	linux-tegra@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-clk@...r.kernel.org,
	dri-devel@...ts.freedesktop.org
Subject: [PATCH v2 2/4] gpu/drm: tegra: dsi: move prepare function at the top of encoder enable

The tegra_dsi_prepare function performs hardware setup and should be
called before any register readings or there will be a risk of device
hangup on register access. To avoid this situation, tegra_dsi_prepare must
be called at the beginning of tegra_dsi_encoder_enable.

Signed-off-by: Svyatoslav Ryhel <clamor95@...il.com>
---
 drivers/gpu/drm/tegra/dsi.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/tegra/dsi.c b/drivers/gpu/drm/tegra/dsi.c
index 278bf2c85524..8e80c7efe8b4 100644
--- a/drivers/gpu/drm/tegra/dsi.c
+++ b/drivers/gpu/drm/tegra/dsi.c
@@ -914,6 +914,12 @@ static void tegra_dsi_encoder_enable(struct drm_encoder *encoder)
 	u32 value;
 	int err;
 
+	err = tegra_dsi_prepare(dsi);
+	if (err < 0) {
+		dev_err(dsi->dev, "failed to prepare: %d\n", err);
+		return;
+	}
+
 	/* If the bootloader enabled DSI it needs to be disabled
 	 * in order for the panel initialization commands to be
 	 * properly sent.
@@ -923,12 +929,6 @@ static void tegra_dsi_encoder_enable(struct drm_encoder *encoder)
 	if (value & DSI_POWER_CONTROL_ENABLE)
 		tegra_dsi_disable(dsi);
 
-	err = tegra_dsi_prepare(dsi);
-	if (err < 0) {
-		dev_err(dsi->dev, "failed to prepare: %d\n", err);
-		return;
-	}
-
 	state = tegra_dsi_get_state(dsi);
 
 	tegra_dsi_set_timeout(dsi, state->bclk, state->vrefresh);
-- 
2.48.1