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Message-ID: <20250618-microchip-lvds-v1-1-1eae5acd7a82@microchip.com>
Date: Wed, 18 Jun 2025 10:02:42 +0530
From: Dharma Balasubiramani <dharma.b@...rochip.com>
To: Manikandan Muralidharan <manikandan.m@...rochip.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>
CC: <dri-devel@...ts.freedesktop.org>, <linux-kernel@...r.kernel.org>,
"Sandeep Sheriker M" <sandeep.sheriker@...rochip.com>, Dharma Balasubiramani
<dharma.b@...rochip.com>
Subject: [PATCH] drm/bridge: fix LVDS controller bus format
From: Sandeep Sheriker M <sandeep.sheriker@...rochip.com>
The current LVDS controller driver is hardcoded to map LVDS lanes to the
JEIDA format. Consequently, connecting an LVDS display that supports the
VESA format results in a distorted display due to the format mismatch.
Query the panel driver and set the appropriate format to resolve the issue.
Signed-off-by: Sandeep Sheriker M <sandeep.sheriker@...rochip.com>
Signed-off-by: Dharma Balasubiramani <dharma.b@...rochip.com>
---
drivers/gpu/drm/bridge/microchip-lvds.c | 108 ++++++++++++++++++++++++++++++--
1 file changed, 102 insertions(+), 6 deletions(-)
diff --git a/drivers/gpu/drm/bridge/microchip-lvds.c b/drivers/gpu/drm/bridge/microchip-lvds.c
index 9f4ff82bc6b4..5e99c01033bb 100644
--- a/drivers/gpu/drm/bridge/microchip-lvds.c
+++ b/drivers/gpu/drm/bridge/microchip-lvds.c
@@ -11,6 +11,7 @@
#include <linux/component.h>
#include <linux/delay.h>
#include <linux/jiffies.h>
+#include <linux/media-bus-format.h>
#include <linux/mfd/syscon.h>
#include <linux/of_graph.h>
#include <linux/pinctrl/devinfo.h>
@@ -41,9 +42,11 @@
/* Bitfields in LVDSC_CFGR (Configuration Register) */
#define LVDSC_CFGR_PIXSIZE_24BITS 0
+#define LVDSC_CFGR_PIXSIZE_18BITS 1
#define LVDSC_CFGR_DEN_POL_HIGH 0
#define LVDSC_CFGR_DC_UNBALANCED 0
#define LVDSC_CFGR_MAPPING_JEIDA BIT(6)
+#define LVDSC_CFGR_MAPPING_VESA 0
/*Bitfields in LVDSC_SR */
#define LVDSC_SR_CS BIT(0)
@@ -58,6 +61,7 @@ struct mchp_lvds {
struct clk *pclk;
struct drm_panel *panel;
struct drm_bridge bridge;
+ struct drm_connector connector;
struct drm_bridge *panel_bridge;
};
@@ -66,6 +70,11 @@ static inline struct mchp_lvds *bridge_to_lvds(struct drm_bridge *bridge)
return container_of(bridge, struct mchp_lvds, bridge);
}
+static inline struct mchp_lvds *drm_connector_to_mchp_lvds(struct drm_connector *connector)
+{
+ return container_of(connector, struct mchp_lvds, connector);
+}
+
static inline u32 lvds_readl(struct mchp_lvds *lvds, u32 offset)
{
return readl_relaxed(lvds->regs + offset);
@@ -79,6 +88,11 @@ static inline void lvds_writel(struct mchp_lvds *lvds, u32 offset, u32 val)
static void lvds_serialiser_on(struct mchp_lvds *lvds)
{
unsigned long timeout = jiffies + msecs_to_jiffies(LVDS_POLL_TIMEOUT_MS);
+ struct drm_connector *connector = &lvds->connector;
+
+ /* default to jeida-24 */
+ u32 bus_formats = MEDIA_BUS_FMT_RGB888_1X7X4_JEIDA;
+ u8 map, pix_size;
/* The LVDSC registers can only be written if WPEN is cleared */
lvds_writel(lvds, LVDSC_WPMR, (LVDSC_WPMR_WPKEY_PSSWD &
@@ -93,24 +107,106 @@ static void lvds_serialiser_on(struct mchp_lvds *lvds)
usleep_range(1000, 2000);
}
+ if (connector && connector->display_info.num_bus_formats)
+ bus_formats = connector->display_info.bus_formats[0];
+
/* Configure the LVDSC */
- lvds_writel(lvds, LVDSC_CFGR, (LVDSC_CFGR_MAPPING_JEIDA |
- LVDSC_CFGR_DC_UNBALANCED |
- LVDSC_CFGR_DEN_POL_HIGH |
- LVDSC_CFGR_PIXSIZE_24BITS));
+ switch (bus_formats) {
+ case MEDIA_BUS_FMT_RGB666_1X7X3_SPWG:
+ map = LVDSC_CFGR_MAPPING_JEIDA;
+ pix_size = LVDSC_CFGR_PIXSIZE_18BITS;
+ break;
+ case MEDIA_BUS_FMT_RGB888_1X7X4_SPWG:
+ map = LVDSC_CFGR_MAPPING_VESA;
+ pix_size = LVDSC_CFGR_PIXSIZE_24BITS;
+ break;
+ default:
+ map = LVDSC_CFGR_MAPPING_JEIDA;
+ pix_size = LVDSC_CFGR_PIXSIZE_24BITS;
+ break;
+ }
+
+ lvds_writel(lvds, LVDSC_CFGR, (map | LVDSC_CFGR_DC_UNBALANCED |
+ LVDSC_CFGR_DEN_POL_HIGH | pix_size));
/* Enable the LVDS serializer */
lvds_writel(lvds, LVDSC_CR, LVDSC_CR_SER_EN);
}
+static int mchp_lvds_connector_get_modes(struct drm_connector *connector)
+{
+ struct mchp_lvds *lvds = drm_connector_to_mchp_lvds(connector);
+
+ return drm_panel_get_modes(lvds->panel, connector);
+}
+
+static const struct drm_connector_helper_funcs mchp_lvds_connector_helper_funcs = {
+ .get_modes = mchp_lvds_connector_get_modes,
+};
+
+static const struct drm_connector_funcs panel_bridge_connector_funcs = {
+ .reset = drm_atomic_helper_connector_reset,
+ .fill_modes = drm_helper_probe_single_connector_modes,
+ .destroy = drm_connector_cleanup,
+ .atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
+ .atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
+};
+
static int mchp_lvds_attach(struct drm_bridge *bridge,
struct drm_encoder *encoder,
enum drm_bridge_attach_flags flags)
{
struct mchp_lvds *lvds = bridge_to_lvds(bridge);
+ struct drm_connector *connector = &lvds->connector;
+ int ret;
+
+ ret = drm_bridge_attach(encoder, lvds->panel_bridge,
+ bridge, flags);
+
+ if (ret < 0)
+ return ret;
+
+ if (flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR)
+ return 0;
+
+ if (!encoder) {
+ dev_err(lvds->dev, "Missing encoder\n");
+ return -ENODEV;
+ }
+
+ drm_connector_helper_add(connector,
+ &mchp_lvds_connector_helper_funcs);
+
+ ret = drm_connector_init(bridge->dev, connector,
+ &panel_bridge_connector_funcs,
+ DRM_MODE_CONNECTOR_LVDS);
+ if (ret) {
+ dev_err(lvds->dev, "Failed to initialize connector %d\n", ret);
+ return ret;
+ }
- return drm_bridge_attach(encoder, lvds->panel_bridge,
- bridge, flags);
+ drm_panel_bridge_set_orientation(connector, bridge);
+
+ ret = drm_connector_attach_encoder(&lvds->connector, encoder);
+ if (ret) {
+ dev_err(lvds->dev, "Failed to attach connector to encoder %d\n", ret);
+ drm_connector_cleanup(connector);
+ return ret;
+ }
+
+ if (bridge->dev->registered) {
+ if (connector->funcs->reset)
+ connector->funcs->reset(connector);
+
+ ret = drm_connector_register(connector);
+ if (ret) {
+ dev_err(lvds->dev, "Failed to attach connector to register %d\n", ret);
+ drm_connector_cleanup(connector);
+ return ret;
+ }
+ }
+
+ return 0;
}
static void mchp_lvds_enable(struct drm_bridge *bridge)
---
base-commit: 4325743c7e209ae7845293679a4de94b969f2bef
change-id: 20250618-microchip-lvds-b7151d96094a
Best regards,
--
Dharma Balasubiramani <dharma.b@...rochip.com>
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