Re: [PATCH v4 10/14] drm/bridge: imx: Add LDB driver helper support

On Wed, 3 Mar 2021 at 08:23, Liu Ying victor.liu@nxp.com wrote:

Hi Robert,

On Tue, 2021-03-02 at 15:22 +0100, Robert Foss wrote:

...

Hey Liu,

Thanks for submitting this patch.

Thanks for reviewing this patch.

...

On Thu, 18 Feb 2021 at 04:59, Liu Ying victor.liu@nxp.com wrote:

...

This patch adds a helper to support LDB drm bridge drivers for i.MX SoCs. Helper functions exported from this driver should implement common logics for all LDB modules embedded in i.MX SoCs.

Signed-off-by: Liu Ying victor.liu@nxp.com

v3->v4:

• No change.

v2->v3:

• Call syscon_node_to_regmap() to get regmap instead of syscon_regmap_lookup_by_phandle().

v1->v2:

• No change.

drivers/gpu/drm/bridge/imx/Kconfig | 8 + drivers/gpu/drm/bridge/imx/Makefile | 1 + drivers/gpu/drm/bridge/imx/imx-ldb-helper.c | 248 ++++++++++++++++++++++++++++ include/drm/bridge/imx_ldb_helper.h | 98 +++++++++++ 4 files changed, 355 insertions(+) create mode 100644 drivers/gpu/drm/bridge/imx/imx-ldb-helper.c create mode 100644 include/drm/bridge/imx_ldb_helper.h

diff --git a/drivers/gpu/drm/bridge/imx/Kconfig b/drivers/gpu/drm/bridge/imx/Kconfig index 1ea1ce7..23e24fd 100644 --- a/drivers/gpu/drm/bridge/imx/Kconfig +++ b/drivers/gpu/drm/bridge/imx/Kconfig @@ -1,3 +1,11 @@ +config DRM_IMX_LVDS_BRIDGE_HELPER

•   tristate "Freescale i.MX LVDS display bridge helper"
  

•   depends on OF
  

•   select DRM_PANEL_BRIDGE
  

•   help
  

•     Helper to support Freescale i.MX LVDS Display Bridge(LDB).
  

•     This bridge is embedded in a SoC.
  

config DRM_IMX8QXP_PIXEL_COMBINER tristate "Freescale i.MX8QM/QXP pixel combiner" depends on OF diff --git a/drivers/gpu/drm/bridge/imx/Makefile b/drivers/gpu/drm/bridge/imx/Makefile index e74dd64..902b703 100644 --- a/drivers/gpu/drm/bridge/imx/Makefile +++ b/drivers/gpu/drm/bridge/imx/Makefile @@ -1,3 +1,4 @@ +obj-$(CONFIG_DRM_IMX_LVDS_BRIDGE_HELPER) += imx-ldb-helper.o obj-$(CONFIG_DRM_IMX8QXP_PIXEL_COMBINER) += imx8qxp-pixel-combiner.o obj-$(CONFIG_DRM_IMX8QXP_PIXEL_LINK) += imx8qxp-pixel-link.o obj-$(CONFIG_DRM_IMX8QXP_PIXEL_LINK_TO_DPI) += imx8qxp-pxl2dpi.o diff --git a/drivers/gpu/drm/bridge/imx/imx-ldb-helper.c b/drivers/gpu/drm/bridge/imx/imx-ldb-helper.c new file mode 100644 index 00000000..94d7f9e --- /dev/null +++ b/drivers/gpu/drm/bridge/imx/imx-ldb-helper.c @@ -0,0 +1,248 @@ +// SPDX-License-Identifier: GPL-2.0+ +/*

• • Copyright (C) 2012 Sascha Hauer, Pengutronix
• • Copyright 2019,2020 NXP
• */

+#include <linux/mfd/syscon.h> +#include <linux/module.h> +#include <linux/of.h> +#include <linux/regmap.h>

+#include <drm/bridge/imx_ldb_helper.h> +#include <drm/drm_of.h> +#include <drm/drm_panel.h> +#include <drm/drm_print.h>

+bool ldb_channel_is_single_link(struct ldb_channel *ldb_ch) +{

•   return ldb_ch->link_type == LDB_CH_SINGLE_LINK;
  

+} +EXPORT_SYMBOL_GPL(ldb_channel_is_single_link);

+bool ldb_channel_is_split_link(struct ldb_channel *ldb_ch) +{

•   return ldb_ch->link_type == LDB_CH_DUAL_LINK_EVEN_ODD_PIXELS ||
  

•          ldb_ch->link_type == LDB_CH_DUAL_LINK_ODD_EVEN_PIXELS;
  

+} +EXPORT_SYMBOL_GPL(ldb_channel_is_split_link);

+int ldb_bridge_atomic_check_helper(struct drm_bridge *bridge,

•                              struct drm_bridge_state *bridge_state,
  

•                              struct drm_crtc_state *crtc_state,
  

•                              struct drm_connector_state *conn_state)
  

+{

•   struct ldb_channel *ldb_ch = bridge->driver_private;
  

•   ldb_ch->in_bus_format = bridge_state->input_bus_cfg.format;
  

•   ldb_ch->out_bus_format = bridge_state->output_bus_cfg.format;
  

•   return 0;
  

+} +EXPORT_SYMBOL_GPL(ldb_bridge_atomic_check_helper);

+void ldb_bridge_mode_set_helper(struct drm_bridge *bridge,

•                           const struct drm_display_mode *mode,
  

•                           const struct drm_display_mode *adjusted_mode)
  

+{

•   struct ldb_channel *ldb_ch = bridge->driver_private;
  

•   struct ldb *ldb = ldb_ch->ldb;
  

•   bool is_split = ldb_channel_is_split_link(ldb_ch);
  

•   if (is_split)
  

•           ldb->ldb_ctrl |= LDB_SPLIT_MODE_EN;
  

•   switch (ldb_ch->out_bus_format) {
  

•   case MEDIA_BUS_FMT_RGB666_1X7X3_SPWG:
  

•           break;
  

•   case MEDIA_BUS_FMT_RGB888_1X7X4_SPWG:
  

•           if (ldb_ch->chno == 0 || is_split)
  

•                   ldb->ldb_ctrl |= LDB_DATA_WIDTH_CH0_24;
  

•           if (ldb_ch->chno == 1 || is_split)
  

•                   ldb->ldb_ctrl |= LDB_DATA_WIDTH_CH1_24;
  

•           break;
  

•   case MEDIA_BUS_FMT_RGB888_1X7X4_JEIDA:
  

•           if (ldb_ch->chno == 0 || is_split)
  

•                   ldb->ldb_ctrl |= LDB_DATA_WIDTH_CH0_24 |
  

•                                    LDB_BIT_MAP_CH0_JEIDA;
  

•           if (ldb_ch->chno == 1 || is_split)
  

•                   ldb->ldb_ctrl |= LDB_DATA_WIDTH_CH1_24 |
  

•                                    LDB_BIT_MAP_CH1_JEIDA;
  

•           break;
  

•   }
  

+} +EXPORT_SYMBOL_GPL(ldb_bridge_mode_set_helper);

+void ldb_bridge_enable_helper(struct drm_bridge *bridge) +{

•   struct ldb_channel *ldb_ch = bridge->driver_private;
  

•   struct ldb *ldb = ldb_ch->ldb;
  

•   /*
  

•    * Platform specific bridge drivers should set ldb_ctrl properly
  

•    * for the enablement, so just write the ctrl_reg here.
  

•    */
  

•   regmap_write(ldb->regmap, ldb->ctrl_reg, ldb->ldb_ctrl);
  

+} +EXPORT_SYMBOL_GPL(ldb_bridge_enable_helper);

+void ldb_bridge_disable_helper(struct drm_bridge *bridge) +{

•   struct ldb_channel *ldb_ch = bridge->driver_private;
  

•   struct ldb *ldb = ldb_ch->ldb;
  

•   bool is_split = ldb_channel_is_split_link(ldb_ch);
  

•   if (ldb_ch->chno == 0 || is_split)
  

•           ldb->ldb_ctrl &= ~LDB_CH0_MODE_EN_MASK;
  

•   if (ldb_ch->chno == 1 || is_split)
  

•           ldb->ldb_ctrl &= ~LDB_CH1_MODE_EN_MASK;
  

•   regmap_write(ldb->regmap, ldb->ctrl_reg, ldb->ldb_ctrl);
  

+} +EXPORT_SYMBOL_GPL(ldb_bridge_disable_helper);

+int ldb_bridge_attach_helper(struct drm_bridge *bridge,

•                        enum drm_bridge_attach_flags flags)
  

+{

•   struct ldb_channel *ldb_ch = bridge->driver_private;
  

•   struct ldb *ldb = ldb_ch->ldb;
  

•   if (!(flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR)) {
  

•           DRM_DEV_ERROR(ldb->dev,
  

•                         "do not support creating a drm_connector\n");
  

•           return -EINVAL;
  

•   }
  

•   if (!bridge->encoder) {
  

•           DRM_DEV_ERROR(ldb->dev, "missing encoder\n");
  

•           return -ENODEV;
  

•   }
  

•   return drm_bridge_attach(bridge->encoder,
  

•                           ldb_ch->next_bridge, bridge,
  

•                           DRM_BRIDGE_ATTACH_NO_CONNECTOR);
  

+} +EXPORT_SYMBOL_GPL(ldb_bridge_attach_helper);

+int ldb_init_helper(struct ldb *ldb) +{

•   struct device *dev = ldb->dev;
  

•   struct device_node *np = dev->of_node;
  

•   struct device_node *child;
  

•   int ret;
  

•   u32 i;
  

•   ldb->regmap = syscon_node_to_regmap(np->parent);
  

•   if (IS_ERR(ldb->regmap)) {
  

•           ret = PTR_ERR(ldb->regmap);
  

•           if (ret != -EPROBE_DEFER)
  

•                   DRM_DEV_ERROR(dev, "failed to get regmap: %d\n", ret);
  

•           return ret;
  

•   }
  

•   for_each_available_child_of_node(np, child) {
  

•           struct ldb_channel *ldb_ch;
  

•           ret = of_property_read_u32(child, "reg", &i);
  

•           if (ret || i > MAX_LDB_CHAN_NUM - 1) {
  

•                   ret = -EINVAL;
  

•                   DRM_DEV_ERROR(dev,
  

•                                 "invalid channel node address: %u\n", i);
  

•                   of_node_put(child);
  

•                   return ret;
  

•           }
  

•           ldb_ch = ldb->channel[i];
  

•           ldb_ch->ldb = ldb;
  

•           ldb_ch->chno = i;
  

•           ldb_ch->is_available = true;
  

•           ldb_ch->np = child;
  

•           ldb->available_ch_cnt++;
  

•   }
  

•   return 0;
  

+} +EXPORT_SYMBOL_GPL(ldb_init_helper);

+int ldb_find_next_bridge_helper(struct ldb *ldb) +{

•   struct device *dev = ldb->dev;
  

•   struct ldb_channel *ldb_ch;
  

•   int ret, i;
  

•   for (i = 0; i < MAX_LDB_CHAN_NUM; i++) {
  

•           ldb_ch = ldb->channel[i];
  

•           if (!ldb_ch->is_available)
  

•                   continue;
  

•           ret = drm_of_find_panel_or_bridge(ldb_ch->np, 1, 0,
  

•                                             &ldb_ch->panel,
  

•                                             &ldb_ch->next_bridge);
  

•           if (ret) {
  

•                   if (ret != -EPROBE_DEFER)
  

•                           DRM_DEV_ERROR(dev,
  

•                                   "failed to find panel or bridge: %d\n",
  

•                                                                   ret);
  

•                   return ret;
  

•           }
  

•           if (ldb_ch->panel) {
  

•                   ldb_ch->next_bridge = devm_drm_panel_bridge_add(dev,
  

•                                                           ldb_ch->panel);
  

•                   if (IS_ERR(ldb_ch->next_bridge)) {
  

•                           ret = PTR_ERR(ldb_ch->next_bridge);
  

•                           DRM_DEV_ERROR(dev,
  

•                                   "failed to add panel bridge: %d\n",
  

•                                                                   ret);
  

•                           return ret;
  

•                   }
  

•           }
  

•   }
  

•   return 0;
  

+} +EXPORT_SYMBOL_GPL(ldb_find_next_bridge_helper);

+void ldb_add_bridge_helper(struct ldb *ldb,

•                      const struct drm_bridge_funcs *bridge_funcs)
  

+{

•   struct ldb_channel *ldb_ch;
  

•   int i;
  

•   for (i = 0; i < MAX_LDB_CHAN_NUM; i++) {
  

•           ldb_ch = ldb->channel[i];
  

•           if (!ldb_ch->is_available)
  

•                   continue;
  

•           ldb_ch->bridge.driver_private = ldb_ch;
  

•           ldb_ch->bridge.funcs = bridge_funcs;
  

•           ldb_ch->bridge.of_node = ldb_ch->np;
  

•           drm_bridge_add(&ldb_ch->bridge);
  

•   }
  

+} +EXPORT_SYMBOL_GPL(ldb_add_bridge_helper);

+void ldb_remove_bridge_helper(struct ldb *ldb) +{

•   struct ldb_channel *ldb_ch;
  

•   int i;
  

•   for (i = 0; i < MAX_LDB_CHAN_NUM; i++) {
  

•           ldb_ch = ldb->channel[i];
  

•           if (!ldb_ch->is_available)
  

•                   continue;
  

•           drm_bridge_remove(&ldb_ch->bridge);
  

•   }
  

+} +EXPORT_SYMBOL_GPL(ldb_remove_bridge_helper);

+MODULE_DESCRIPTION("Freescale i.MX LVDS Display Bridge driver helper"); +MODULE_AUTHOR("Liu Ying victor.liu@nxp.com"); +MODULE_LICENSE("GPL v2"); +MODULE_ALIAS("platform:imx-ldb-helper");

I'm not entirely sure why this set of helper functions should be a module. It's not a driver, but rather a toolbox for the LDB driver, which is fine, but there is no situation I can see where this module would be unloaded and the LDB driver would be loaded.

I can see drivers/gpu/drm/drm_mipi_dbi.c is also a module and essentially provides helpers to MIPI DBI drivers, but it is not a driver. I don't see this imx-ldb-helper can be anything else other than a module.

Or, do you mean that imx-ldb-helper should be only built-in?

My thinking was that it should just be linked together with the rest of the imx8qxp-ldb driver. But this ties in to my next comment.

...

...

diff --git a/include/drm/bridge/imx_ldb_helper.h b/include/drm/bridge/imx_ldb_helper.h new file mode 100644 index 00000000..2a7ba97 --- /dev/null +++ b/include/drm/bridge/imx_ldb_helper.h

This header is specific to this driver, and I would expect it to not be useful to other drivers. Additionally the filename has a different format than the .c file it corresponds to. I would change the name and path to "drivers/gpu/drm/bridge/imx/imx-ldb-helper.h".

The i.MX53/6qdl LDB driver(drivers/gpu/drm/imx/imx-ldb.c) can potentially use this header, but it's a DRM encoder driver. So, maybe, it's a good idea to move this header to the 'drivers' folder and rename it to 'imx-ldb-helper.h' ofc. If no objections, I'll do as what you're suggesting here in the next version.

Ah I see. If ldb-helper is indeed used by two drivers, making it a module seems reasonable.

I think we have two options then.

#1 Make imx-ldb-helper an object that is just linked with the imx8qxp-ldb driver.

#2 Keep imx-ldb-helper as a module, and implement support for using it in the imx-ldb driver. Ideally I'd like to see the imx-ldb-helper module patch in the same series as as imx53/6qdl switching to using the module. These things have a tendency of not happening if not done right away :)

Regards, Liu Ying

...

...

@@ -0,0 +1,98 @@ +/* SPDX-License-Identifier: GPL-2.0+ */

+/*

• • Copyright 2019,2020 NXP
• */

+#ifndef __FSL_IMX_LDB__ +#define __FSL_IMX_LDB__

+#include <linux/device.h> +#include <linux/kernel.h> +#include <linux/of.h> +#include <linux/regmap.h>

+#include <drm/drm_atomic.h> +#include <drm/drm_bridge.h> +#include <drm/drm_device.h> +#include <drm/drm_encoder.h> +#include <drm/drm_modeset_helper_vtables.h> +#include <drm/drm_panel.h>

+#define LDB_CH0_MODE_EN_TO_DI0 (1 << 0) +#define LDB_CH0_MODE_EN_TO_DI1 (3 << 0) +#define LDB_CH0_MODE_EN_MASK (3 << 0) +#define LDB_CH1_MODE_EN_TO_DI0 (1 << 2) +#define LDB_CH1_MODE_EN_TO_DI1 (3 << 2) +#define LDB_CH1_MODE_EN_MASK (3 << 2) +#define LDB_SPLIT_MODE_EN (1 << 4) +#define LDB_DATA_WIDTH_CH0_24 (1 << 5) +#define LDB_BIT_MAP_CH0_JEIDA (1 << 6) +#define LDB_DATA_WIDTH_CH1_24 (1 << 7) +#define LDB_BIT_MAP_CH1_JEIDA (1 << 8) +#define LDB_DI0_VS_POL_ACT_LOW (1 << 9) +#define LDB_DI1_VS_POL_ACT_LOW (1 << 10)

+#define MAX_LDB_CHAN_NUM 2

+enum ldb_channel_link_type {

•   LDB_CH_SINGLE_LINK,
  

•   LDB_CH_DUAL_LINK_EVEN_ODD_PIXELS,
  

•   LDB_CH_DUAL_LINK_ODD_EVEN_PIXELS,
  

+};

+struct ldb;

+struct ldb_channel {

•   struct ldb *ldb;
  

•   struct drm_bridge bridge;
  

•   struct drm_panel *panel;
  

•   struct drm_bridge *next_bridge;
  

•   struct device_node *np;
  

•   u32 chno;
  

•   bool is_available;
  

•   u32 in_bus_format;
  

•   u32 out_bus_format;
  

•   enum ldb_channel_link_type link_type;
  

+};

+struct ldb {

•   struct regmap *regmap;
  

•   struct device *dev;
  

•   struct ldb_channel *channel[MAX_LDB_CHAN_NUM];
  

•   unsigned int ctrl_reg;
  

•   u32 ldb_ctrl;
  

•   unsigned int available_ch_cnt;
  

+};

+#define bridge_to_ldb_ch(b) container_of(b, struct ldb_channel, bridge)

+bool ldb_channel_is_single_link(struct ldb_channel *ldb_ch); +bool ldb_channel_is_split_link(struct ldb_channel *ldb_ch);

+int ldb_bridge_atomic_check_helper(struct drm_bridge *bridge,

•                              struct drm_bridge_state *bridge_state,
  

•                              struct drm_crtc_state *crtc_state,
  

•                              struct drm_connector_state *conn_state);
  

+void ldb_bridge_mode_set_helper(struct drm_bridge *bridge,

•                           const struct drm_display_mode *mode,
  

•                           const struct drm_display_mode *adjusted_mode);
  

+void ldb_bridge_enable_helper(struct drm_bridge *bridge);

+void ldb_bridge_disable_helper(struct drm_bridge *bridge);

+int ldb_bridge_attach_helper(struct drm_bridge *bridge,

•                        enum drm_bridge_attach_flags flags);
  

+int ldb_init_helper(struct ldb *ldb);

+int ldb_find_next_bridge_helper(struct ldb *ldb);

+void ldb_add_bridge_helper(struct ldb *ldb,

•                      const struct drm_bridge_funcs *bridge_funcs);
  

+void ldb_remove_bridge_helper(struct ldb *ldb);

+#endif /* __FSL_IMX_LDB__ */

2.7.4