linux-kernel - [PATCH 14/32] drm/mipi-dsi: add .attach_new to mipi_dsi_host

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Message-Id: <20250625-drm-dsi-host-no-device-ptr-v1-14-e36bc258a7c5@bootlin.com>
Date: Wed, 25 Jun 2025 18:45:18 +0200
From: Luca Ceresoli <luca.ceresoli@...tlin.com>
To: 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>, 
 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>, 
 Inki Dae <inki.dae@...sung.com>, Jagan Teki <jagan@...rulasolutions.com>, 
 Marek Szyprowski <m.szyprowski@...sung.com>, 
 Jani Nikula <jani.nikula@...ux.intel.com>, 
 Dmitry Baryshkov <lumag@...nel.org>
Cc: Hui Pu <Hui.Pu@...ealthcare.com>, 
 Thomas Petazzoni <thomas.petazzoni@...tlin.com>, 
 dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org, 
 linux-sunxi@...ts.linux.dev, Luca Ceresoli <luca.ceresoli@...tlin.com>
Subject: [PATCH 14/32] drm/mipi-dsi: add .attach_new to mipi_dsi_host_ops

In preparation to avoid DSI host drivers to take any pointer to struct
mipi_dsi_device, add a new host op which does not take such pointer. The
old op can be removed once all users are converted to the new one.

The .attach_new op takes the DSI device format values, (part of) which are
needed by most DSI host drivers. It passes a temporary struct, in order to
ensure host drivers copy the values they need and not keep a pointer.

The struct with the data (struct mipi_dsi_bus_fmt) is a subset of struct
mipi_dsi_device. After all host drivers are converted, struct
mipi_dsi_device can be modified to hold a struct mipi_dsi_bus_fmt instead
of individual fields.

Signed-off-by: Luca Ceresoli <luca.ceresoli@...tlin.com>
---
 drivers/gpu/drm/drm_mipi_dsi.c | 21 +++++++++++++++++++--
 include/drm/drm_mipi_dsi.h     | 29 ++++++++++++++++++++++++++++-
 2 files changed, 47 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/drm_mipi_dsi.c b/drivers/gpu/drm/drm_mipi_dsi.c
index f16f70c70c87988a95f959d0b8b18a6941dd2808..f45425f777f6bed6ac5f261b0097455c52ab7d9e 100644
--- a/drivers/gpu/drm/drm_mipi_dsi.c
+++ b/drivers/gpu/drm/drm_mipi_dsi.c
@@ -367,6 +367,18 @@ void mipi_dsi_host_unregister(struct mipi_dsi_host *host)
 }
 EXPORT_SYMBOL(mipi_dsi_host_unregister);
 
+static void mipi_dsi_dev_copy_bus_fmt(struct mipi_dsi_bus_fmt *fmt,
+				      const struct mipi_dsi_device *dsi_dev)
+{
+	fmt->channel	= dsi_dev->channel;
+	fmt->lanes	= dsi_dev->lanes;
+	fmt->format	= dsi_dev->format;
+	fmt->mode_flags	= dsi_dev->mode_flags;
+	fmt->hs_rate	= dsi_dev->hs_rate;
+	fmt->lp_rate	= dsi_dev->lp_rate;
+	fmt->dsc	= dsi_dev->dsc;
+}
+
 /**
  * mipi_dsi_attach - attach a DSI device to its DSI host
  * @dsi: DSI peripheral
@@ -374,15 +386,20 @@ EXPORT_SYMBOL(mipi_dsi_host_unregister);
 int mipi_dsi_attach(struct mipi_dsi_device *dsi)
 {
 	const struct mipi_dsi_host_ops *ops = dsi->host->ops;
+	struct mipi_dsi_bus_fmt bus_fmt;
 	int ret;
 
-	if (!ops || !ops->attach)
+	if (!ops || !(ops->attach_new || ops->attach))
 		return -ENOSYS;
 
 	if (dsi->lanes < 1)
 		return dev_err_probe(&dsi->dev, -EINVAL, "Incorrect lanes number\n");
 
-	ret = ops->attach(dsi->host, dsi);
+	mipi_dsi_dev_copy_bus_fmt(&bus_fmt, dsi);
+
+	ret = ops->attach_new ?
+		ops->attach_new(dsi->host, &bus_fmt) :
+		ops->attach(dsi->host, dsi);
 	if (ret) {
 		dev_err(dsi->host->dev,
 			"Failed to attach %s device (lanes:%d bpp:%d mode-flags:0x%lx) (%d)\n",
diff --git a/include/drm/drm_mipi_dsi.h b/include/drm/drm_mipi_dsi.h
index e42483fd022fed4dfc9e5ef180117c3dd37a3b51..5d5f3dca1ec1a654378ccca15f3f15a5ce957518 100644
--- a/include/drm/drm_mipi_dsi.h
+++ b/include/drm/drm_mipi_dsi.h
@@ -102,9 +102,34 @@ enum mipi_dsi_pixel_format {
 
 #define DSI_DEV_NAME_SIZE		20
 
+/**
+ * struct mipi_dsi_bus_fmt - format required by a DSI peripheral device
+ * @channel: virtual channel assigned to the peripheral
+ * @format: pixel format for video mode
+ * @lanes: number of active data lanes
+ * @mode_flags: DSI operation mode related flags
+ * @hs_rate: maximum lane frequency for high speed mode in hertz, this should
+ * be set to the real limits of the hardware, zero is only accepted for
+ * legacy drivers
+ * @lp_rate: maximum lane frequency for low power mode in hertz, this should
+ * be set to the real limits of the hardware, zero is only accepted for
+ * legacy drivers
+ * @dsc: panel/bridge DSC pps payload to be sent
+ */
+struct mipi_dsi_bus_fmt {
+	unsigned int channel;
+	unsigned int lanes;
+	enum mipi_dsi_pixel_format format;
+	unsigned long mode_flags;
+	unsigned long hs_rate;
+	unsigned long lp_rate;
+	struct drm_dsc_config *dsc;
+};
+
 /**
  * struct mipi_dsi_host_ops - DSI bus operations
- * @attach: attach DSI device to DSI host
+ * @attach_new: attach DSI device to DSI host; either @attach_new or @attach is mandatory
+ * @attach: deprecated version of @attach_new
  * @detach: detach DSI device from DSI host
  * @transfer: transmit a DSI packet
  *
@@ -126,6 +151,8 @@ enum mipi_dsi_pixel_format {
  * properly enabled.
  */
 struct mipi_dsi_host_ops {
+	int (*attach_new)(struct mipi_dsi_host *host,
+			  const struct mipi_dsi_bus_fmt *bus_fmt);
 	int (*attach)(struct mipi_dsi_host *host,
 		      struct mipi_dsi_device *dsi);
 	int (*detach)(struct mipi_dsi_host *host,

-- 
2.49.0