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Message-ID: <9f86afed1282a5749f416b0e5b9a39a1f972017a.camel@nxp.com>
Subject: Re: (EXT) [PATCH v8 09/14] drm/bridge: imx: Add LDB driver helper
 support
From:   Liu Ying <victor.liu@nxp.com>
To:     Alexander Stein <alexander.stein@ew.tq-group.com>
Cc:     dri-devel@lists.freedesktop.org, devicetree@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        linux-media@vger.kernel.org, andrzej.hajda@intel.com,
        narmstrong@baylibre.com, robert.foss@linaro.org,
        Laurent.pinchart@ideasonboard.com, jonas@kwiboo.se,
        jernej.skrabec@gmail.com, airlied@linux.ie, daniel@ffwll.ch,
        robh+dt@kernel.org, krzysztof.kozlowski+dt@linaro.org,
        shawnguo@kernel.org, s.hauer@pengutronix.de, kernel@pengutronix.de,
        festevam@gmail.com, linux-imx@nxp.com, lee.jones@linaro.org,
        mchehab@kernel.org, marcel.ziswiler@toradex.com
Date:   Fri, 10 Jun 2022 11:01:21 +0800
In-Reply-To: <4748166.31r3eYUQgx@steina-w>
References: <20220609064931.3068601-1-victor.liu@nxp.com>
         <20220609064931.3068601-10-victor.liu@nxp.com>
         <4748166.31r3eYUQgx@steina-w>
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On Thu, 2022-06-09 at 09:47 +0200, Alexander Stein wrote:
> Am Donnerstag, 9. Juni 2022, 08:49:26 CEST schrieb Liu Ying:
> > This patch adds a helper to support LDB drm bridge drivers for
> > i.MX SoCs.  Helper functions supported by this helper should
> > implement common logics for all LDB modules embedded in i.MX SoCs.
> > 
> > Tested-by: Marcel Ziswiler <marcel.ziswiler@toradex.com> # Colibri
> > iMX8X,
> > LT170410-2WHC, LP156WF1 Reviewed-by: Robert Foss <
> > robert.foss@linaro.org>
> > Signed-off-by: Liu Ying <victor.liu@nxp.com>
> > ---
> 
> Hi,

Hi,

> 
> reading this I got reminded of fsl-ldb [1], which is accepted
> already. At a 
> first glance reading the RM the LDB peripheral are similar, although
> not 
> identical. Is it worth merging them into one driver (at some point)?

fsl-ldb is for i.MX8mp LDB. It couples the lvds phy(LVDS_CTRL register)
with LDB(LDB_CTRL register) hardly.

Eventually, I think there would be separate LDB bridge drivers for
i.MX8mp/qxp/qm LDBs, as they are far or less different(LVDS PHY IPs,
clocks, ways of dual link usage...). So, maybe, the question is that
can fsl-ldb use this LDB helper driver. AFAICS, the different DT
bindings between i.MX8mp LDB and i.MX8qxp/qm LDB make this difficult. 
This LDB helper takes each LDB child node(channel node) of i.MX8qxp/qm
as a bridge, while i.MX8mp LDB bindings put input and output ports in
'ports' node.  Like i.MX8qxp/qm LDB, i.MX6 LDB
binding(Documentation/devicetree/bindings/display/imx/ldb.txt) also
uses 'channel' nodes, though i.MX6 LDB has a separate encoder driver.
I think the 'channel' node better reflects HW design.
So, maybe, fsl-ldb for i.MX8mp won't use this LDB helper.

Regards,
Liu Ying

> 
> Best regards,
> Alexander
> 
> [1] 
> https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fpatchwork.freedesktop.org%2Fpatch%2Fmsgid%2F20220426193645.244792-2-marex%40denx.de&amp;data=05%7C01%7Cvictor.liu%40nxp.com%7Ca4ee326b3f314cf48a3408da49ec5a33%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C0%7C637903576722519563%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&amp;sdata=yJhovCeB7Dx2eWJqKohZskA7fX3NLwqmW1GxeQlDe40%3D&amp;reserved=0
> 
> > Marcel, I add your T-b tag from v6, let me know if you want me to
> > drop it,
> > as the checkpatch fix in v7 and the rebase in v8 are trivial.
> > 
> > v7->v8:
> > * Use devm_drm_of_get_bridge() due to the rebase upon v5.19-rc1.
> > 
> > v6->v7:
> > * Fix below complaints from 'checkpatch.pl --strict'. (Robert)
> >    - 'Alignment should match open parenthesis'
> >    - 'Prefer using the BIT macro'
> > * Add Marcel's T-b tag.
> > * Add Robert's R-b tag.
> > 
> > v5->v6:
> > * No change.
> > 
> > v4->v5:
> > * Make imx-ldb-helper be a pure object to be linked with i.MX8qxp
> > LDB bridge
> > driver and i.MX8qm LDB bridge driver. (Robert)
> > * Move 'imx_ldb_helper.h' to 'drivers/gpu/drm/bridge/imx/imx-ldb-
> > helper.h'.
> >   (Robert)
> > * s/__FSL_IMX_LDB__/__IMX_LDB_HELPER__/  for 'imx-ldb-helper.h'.
> > 
> > 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/imx-ldb-helper.c | 220
> > ++++++++++++++++++++
> >  drivers/gpu/drm/bridge/imx/imx-ldb-helper.h |  96 +++++++++
> >  2 files changed, 316 insertions(+)
> >  create mode 100644 drivers/gpu/drm/bridge/imx/imx-ldb-helper.c
> >  create mode 100644 drivers/gpu/drm/bridge/imx/imx-ldb-helper.h
> > 
> > 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 000000000000..e85eb9ab5947
> > --- /dev/null
> > +++ b/drivers/gpu/drm/bridge/imx/imx-ldb-helper.c
> > @@ -0,0 +1,220 @@
> > +// SPDX-License-Identifier: GPL-2.0+
> > +/*
> > + * Copyright (C) 2012 Sascha Hauer, Pengutronix
> > + * Copyright 2019,2020,2022 NXP
> > + */
> > +
> > +#include <linux/mfd/syscon.h>
> > +#include <linux/of.h>
> > +#include <linux/regmap.h>
> > +
> > +#include <drm/drm_bridge.h>
> > +#include <drm/drm_of.h>
> > +#include <drm/drm_print.h>
> > +
> > +#include "imx-ldb-helper.h"
> > +
> > +bool ldb_channel_is_single_link(struct ldb_channel *ldb_ch)
> > +{
> > +	return ldb_ch->link_type == LDB_CH_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;
> > +}
> > +
> > +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;
> > +}
> > +
> > +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;
> > +	}
> > +}
> > +
> > +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);
> > +}
> > +
> > +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);
> > +}
> > +
> > +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);
> > +}
> > +
> > +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;
> > +}
> > +
> > +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;
> > +
> > +		ldb_ch->next_bridge = devm_drm_of_get_bridge(dev, 
> 
> ldb_ch->np,
> > +							     
> 
> 1, 0);
> > +		if (IS_ERR(ldb_ch->next_bridge)) {
> > +			ret = PTR_ERR(ldb_ch->next_bridge);
> > +			if (ret != -EPROBE_DEFER)
> > +				DRM_DEV_ERROR(dev,
> > +					      "failed to get 
> 
> next bridge: %d\n",
> > +					      ret);
> > +			return ret;
> > +		}
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> > +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);
> > +	}
> > +}
> > +
> > +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);
> > +	}
> > +}
> > diff --git a/drivers/gpu/drm/bridge/imx/imx-ldb-helper.h
> > b/drivers/gpu/drm/bridge/imx/imx-ldb-helper.h new file mode 100644
> > index 000000000000..a0a5cde27fbc
> > --- /dev/null
> > +++ b/drivers/gpu/drm/bridge/imx/imx-ldb-helper.h
> > @@ -0,0 +1,96 @@
> > +/* SPDX-License-Identifier: GPL-2.0+ */
> > +
> > +/*
> > + * Copyright 2019,2020,2022 NXP
> > + */
> > +
> > +#ifndef __IMX_LDB_HELPER__
> > +#define __IMX_LDB_HELPER__
> > +
> > +#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>
> > +
> > +#define LDB_CH0_MODE_EN_TO_DI0		BIT(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		BIT(2)
> > +#define LDB_CH1_MODE_EN_TO_DI1		(3 << 2)
> > +#define LDB_CH1_MODE_EN_MASK		(3 << 2)
> > +#define LDB_SPLIT_MODE_EN		BIT(4)
> > +#define LDB_DATA_WIDTH_CH0_24		BIT(5)
> > +#define LDB_BIT_MAP_CH0_JEIDA		BIT(6)
> > +#define LDB_DATA_WIDTH_CH1_24		BIT(7)
> > +#define LDB_BIT_MAP_CH1_JEIDA		BIT(8)
> > +#define LDB_DI0_VS_POL_ACT_LOW		BIT(9)
> > +#define LDB_DI1_VS_POL_ACT_LOW		BIT(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_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 /* __IMX_LDB_HELPER__ */
> 
> 
> 
>