linux-kernel - [PATCH v3 03/13] drm/bridge: samsung-dsim: add flag to control header FIFO wait

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Message-Id: <20250706-exynos7870-dsim-v3-3-9879fb9a644d@disroot.org>
Date: Sun, 06 Jul 2025 23:55:37 +0530
From: Kaustabh Chakraborty <kauschluss@...root.org>
To: Inki Dae <inki.dae@...sung.com>, 
 Jagan Teki <jagan@...rulasolutions.com>, 
 Marek Szyprowski <m.szyprowski@...sung.com>, 
 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>, 
 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>, Seung-Woo Kim <sw0312.kim@...sung.com>, 
 Kyungmin Park <kyungmin.park@...sung.com>, 
 Krzysztof Kozlowski <krzk@...nel.org>, 
 Alim Akhtar <alim.akhtar@...sung.com>
Cc: dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org, 
 devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
 linux-samsung-soc@...r.kernel.org, 
 Kaustabh Chakraborty <kauschluss@...root.org>
Subject: [PATCH v3 03/13] drm/bridge: samsung-dsim: add flag to control
 header FIFO wait

Exynos7870's DSIM device doesn't require waiting for the header FIFO
during a MIPI DSI transfer. Add a flag in the driver data in order to
control said behavior.

Signed-off-by: Kaustabh Chakraborty <kauschluss@...root.org>
---
 drivers/gpu/drm/bridge/samsung-dsim.c | 15 ++++++++++++---
 include/drm/bridge/samsung-dsim.h     |  1 +
 2 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/bridge/samsung-dsim.c b/drivers/gpu/drm/bridge/samsung-dsim.c
index dca3939dd99fa07aee309067b93e652bc9a9b78f..84af24171b6856cbcf95b9077b997ee587fc0409 100644
--- a/drivers/gpu/drm/bridge/samsung-dsim.c
+++ b/drivers/gpu/drm/bridge/samsung-dsim.c
@@ -418,6 +418,7 @@ static const struct samsung_dsim_driver_data exynos3_dsi_driver_data = {
 	.has_clklane_stop = 1,
 	.num_clks = 2,
 	.max_freq = 1000,
+	.wait_for_hdr_fifo = 1,
 	.wait_for_reset = 1,
 	.num_bits_resol = 11,
 	.pll_p_offset = 13,
@@ -438,6 +439,7 @@ static const struct samsung_dsim_driver_data exynos4_dsi_driver_data = {
 	.has_clklane_stop = 1,
 	.num_clks = 2,
 	.max_freq = 1000,
+	.wait_for_hdr_fifo = 1,
 	.wait_for_reset = 1,
 	.num_bits_resol = 11,
 	.pll_p_offset = 13,
@@ -456,6 +458,7 @@ static const struct samsung_dsim_driver_data exynos5_dsi_driver_data = {
 	.has_legacy_status_reg = 1,
 	.num_clks = 2,
 	.max_freq = 1000,
+	.wait_for_hdr_fifo = 1,
 	.wait_for_reset = 1,
 	.num_bits_resol = 11,
 	.pll_p_offset = 13,
@@ -474,6 +477,7 @@ static const struct samsung_dsim_driver_data exynos5433_dsi_driver_data = {
 	.has_clklane_stop = 1,
 	.num_clks = 5,
 	.max_freq = 1500,
+	.wait_for_hdr_fifo = 1,
 	.wait_for_reset = 0,
 	.num_bits_resol = 12,
 	.pll_p_offset = 13,
@@ -492,6 +496,7 @@ static const struct samsung_dsim_driver_data exynos5422_dsi_driver_data = {
 	.has_clklane_stop = 1,
 	.num_clks = 2,
 	.max_freq = 1500,
+	.wait_for_hdr_fifo = 1,
 	.wait_for_reset = 1,
 	.num_bits_resol = 12,
 	.pll_p_offset = 13,
@@ -510,6 +515,7 @@ static const struct samsung_dsim_driver_data imx8mm_dsi_driver_data = {
 	.has_clklane_stop = 1,
 	.num_clks = 2,
 	.max_freq = 2100,
+	.wait_for_hdr_fifo = 1,
 	.wait_for_reset = 0,
 	.num_bits_resol = 12,
 	/*
@@ -1117,6 +1123,7 @@ static void samsung_dsim_send_to_fifo(struct samsung_dsim *dsi,
 {
 	struct device *dev = dsi->dev;
 	struct mipi_dsi_packet *pkt = &xfer->packet;
+	const struct samsung_dsim_driver_data *driver_data = dsi->driver_data;
 	const u8 *payload = pkt->payload + xfer->tx_done;
 	u16 length = pkt->payload_length - xfer->tx_done;
 	bool first = !xfer->tx_done;
@@ -1157,9 +1164,11 @@ static void samsung_dsim_send_to_fifo(struct samsung_dsim *dsi,
 		return;
 
 	reg = get_unaligned_le32(pkt->header);
-	if (samsung_dsim_wait_for_hdr_fifo(dsi)) {
-		dev_err(dev, "waiting for header FIFO timed out\n");
-		return;
+	if (driver_data->wait_for_hdr_fifo) {
+		if (samsung_dsim_wait_for_hdr_fifo(dsi)) {
+			dev_err(dev, "waiting for header FIFO timed out\n");
+			return;
+		}
 	}
 
 	if (NEQV(xfer->flags & MIPI_DSI_MSG_USE_LPM,
diff --git a/include/drm/bridge/samsung-dsim.h b/include/drm/bridge/samsung-dsim.h
index f0c1e5c5ed490afe0bcfd06830f52471710b29ea..62c07952bd00f9c2c287a6a998f0e243dd4032a9 100644
--- a/include/drm/bridge/samsung-dsim.h
+++ b/include/drm/bridge/samsung-dsim.h
@@ -61,6 +61,7 @@ struct samsung_dsim_driver_data {
 	unsigned int num_clks;
 	unsigned int min_freq;
 	unsigned int max_freq;
+	unsigned int wait_for_hdr_fifo;
 	unsigned int wait_for_reset;
 	unsigned int num_bits_resol;
 	unsigned int pll_p_offset;

-- 
2.49.0