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

Hi Robert,

On Wed, 2021-03-03 at 16:34 +0100, Robert Foss wrote:

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:

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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.

This patch set contains _two_ modules which use the imx-ldb-helper, i.e., the imx8qxp-ldb driver(patch 12/14) and the imx8qm-ldb driver(patch 13/14). It looks that we cannot link the imx-ldb-helper with them respectively. So, I think keeping imx-ldb-helper as a module is the only option.

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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.

Yes, for now, two drivers(imx8qxp-ldb and imx8qm-ldb) use imx-ldb-helper.

I think we have two options then.

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

I don't think #1 is a valid option, as we cannot link imx-ldb-helper object with imx8qxp-ldb driver and imx8qm-ldb driver respectively.

#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 :)

As I mentioned before, the i.MX53/6qdl LDB driver(imx-ldb) is a DRM encoder driver. It doesn't look straight-forward to include a header for bridge drivers there.

An alternative is to first convert imx-ldb to be a pure bridge driver(called imx53-ldb.c, perhaps) and to put it in drivers/gpu/drm/bridge/imx folder. But, it's not an easy task, because the imx-drm for i.MX51/53/6dql IPU display controller needs to create DRM encoders & connectors instead, and the other relevant encoder drivers (imx-tve, parallel-display and dw_hdmi-imx) needs to be converted to bridge drivers as well. This is not what this patch set can cover, IMHO. Perhaps, it will be done later on.

In all, it looks ok to keep imx-ldb-helper as a module and move the header(imx-ldb-helper.h) to the 'drivers' folder. Agree?

Regards, Liu Ying

...

Regards, Liu Ying

...

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@@ -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