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Date: Sun, 26 Jul 2020 09:15:17 +0200
From: Sam Ravnborg <sam@ravnborg.org>
To: Marek Vasut <marex@denx.de>
Subject: Re: [PATCH 2/2] drm/bridge: tc358762: Add basic driver for Toshiba
 TC358762 DSI-to-DPI bridge
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Hi Marek.

On Sat, Jul 25, 2020 at 11:14:57PM +0200, Marek Vasut wrote:
> Add very basic driver for Toshiba TC358762 DSI-to-DPI bridge, derived
> from tc358764 driver and panel-raspberrypi-touchscreen. This driver is
> meant to replace the panel-raspberrypi-touchscreen too, as the bridge
> connection can be described in DT too.
> 
> Signed-off-by: Marek Vasut <marex@denx.de>
> To: dri-devel@lists.freedesktop.org
> Cc: Eric Anholt <eric@anholt.net>
> Cc: Rob Herring <robh+dt@kernel.org>
> Cc: Sam Ravnborg <sam@ravnborg.org>
> Cc: devicetree@vger.kernel.org
> ---

Two general comments.
- This driver should use the bridge panel - this will simplify the
  driver in many places. We already have several good examples in-tree
  that does this.

- The driver does not respect the "flags" argument in the attach
  operation. All new bridge drivers shall respect the flags operation to
  prepare for use in a setup with chained bridges.
  In short the flags is used to determine if the display driver or the
  bridge creates the connector.
  When the bridge panel is introduced you can drop all the connector
  creation code and just pass the flag to the bridge panel.
  The bridge panel will then create the connector if requested.
  This is possible because this simple bridge driver does not add
  anything to the connector that the bridge panel does not know.

	Sam


>  drivers/gpu/drm/bridge/Kconfig    |   9 +
>  drivers/gpu/drm/bridge/Makefile   |   1 +
>  drivers/gpu/drm/bridge/tc358762.c | 352 ++++++++++++++++++++++++++++++
>  3 files changed, 362 insertions(+)
>  create mode 100644 drivers/gpu/drm/bridge/tc358762.c
> 
> diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
> index 43271c21d3fc..3e76e3fccb78 100644
> --- a/drivers/gpu/drm/bridge/Kconfig
> +++ b/drivers/gpu/drm/bridge/Kconfig
> @@ -153,6 +153,15 @@ config DRM_THINE_THC63LVD1024
>  	help
>  	  Thine THC63LVD1024 LVDS/parallel converter driver.
>  
> +config DRM_TOSHIBA_TC358762
> +	tristate "TC358762 DSI/DPI bridge"
> +	depends on OF
> +	select DRM_MIPI_DSI
> +	select DRM_KMS_HELPER
> +	select DRM_PANEL
> +	help
> +	  Toshiba TC358762 DSI/DPI bridge driver.
> +
>  config DRM_TOSHIBA_TC358764
>  	tristate "TC358764 DSI/LVDS bridge"
>  	depends on OF
> diff --git a/drivers/gpu/drm/bridge/Makefile b/drivers/gpu/drm/bridge/Makefile
> index d63d4b7e4347..b341c60ee96a 100644
> --- a/drivers/gpu/drm/bridge/Makefile
> +++ b/drivers/gpu/drm/bridge/Makefile
> @@ -12,6 +12,7 @@ obj-$(CONFIG_DRM_SII902X) += sii902x.o
>  obj-$(CONFIG_DRM_SII9234) += sii9234.o
>  obj-$(CONFIG_DRM_SIMPLE_BRIDGE) += simple-bridge.o
>  obj-$(CONFIG_DRM_THINE_THC63LVD1024) += thc63lvd1024.o
> +obj-$(CONFIG_DRM_TOSHIBA_TC358762) += tc358762.o
>  obj-$(CONFIG_DRM_TOSHIBA_TC358764) += tc358764.o
>  obj-$(CONFIG_DRM_TOSHIBA_TC358767) += tc358767.o
>  obj-$(CONFIG_DRM_TOSHIBA_TC358768) += tc358768.o
> diff --git a/drivers/gpu/drm/bridge/tc358762.c b/drivers/gpu/drm/bridge/tc358762.c
> new file mode 100644
> index 000000000000..6eb0c0c10623
> --- /dev/null
> +++ b/drivers/gpu/drm/bridge/tc358762.c
> @@ -0,0 +1,352 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2020 Marek Vasut <marex@denx.de>
> + *
> + * Based on tc358764.c by
> + *  Andrzej Hajda <a.hajda@samsung.com>
> + *  Maciej Purski <m.purski@samsung.com>
Someone should finish the conversion of tc358764.c to the new bridge API
(that someone is me).

> + *
> + * Based on rpi_touchscreen.c by
> + *  Eric Anholt <eric@anholt.net>
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/module.h>
> +#include <linux/of_graph.h>
> +#include <linux/regulator/consumer.h>
> +
> +#include <video/mipi_display.h>
> +
> +#include <drm/drm_atomic_helper.h>
> +#include <drm/drm_crtc.h>
> +#include <drm/drm_fb_helper.h>
> +#include <drm/drm_mipi_dsi.h>
> +#include <drm/drm_of.h>
> +#include <drm/drm_panel.h>
> +#include <drm/drm_print.h>
> +#include <drm/drm_probe_helper.h>
> +
> +/* PPI layer registers */
> +#define PPI_STARTPPI		0x0104 /* START control bit */
> +#define PPI_LPTXTIMECNT		0x0114 /* LPTX timing signal */
> +#define PPI_D0S_ATMR		0x0144
> +#define PPI_D1S_ATMR		0x0148
> +#define PPI_D0S_CLRSIPOCOUNT	0x0164 /* Assertion timer for Lane 0 */
> +#define PPI_D1S_CLRSIPOCOUNT	0x0168 /* Assertion timer for Lane 1 */
> +#define PPI_START_FUNCTION	1
> +
> +/* DSI layer registers */
> +#define DSI_STARTDSI		0x0204 /* START control bit of DSI-TX */
> +#define DSI_LANEENABLE		0x0210 /* Enables each lane */
> +#define DSI_RX_START		1
> +
> +/* LCDC/DPI Host Registers */
> +#define LCDCTRL			0x0420
> +
> +/* SPI Master Registers */
> +#define SPICMR			0x0450
> +#define SPITCR			0x0454
> +
> +/* System Controller Registers */
> +#define SYSCTRL			0x0464
> +
> +/* System registers */
> +#define LPX_PERIOD		3
> +
> +/* Lane enable PPI and DSI register bits */
> +#define LANEENABLE_CLEN		BIT(0)
> +#define LANEENABLE_L0EN		BIT(1)
> +#define LANEENABLE_L1EN		BIT(2)
> +
> +struct tc358762 {
> +	struct device *dev;
> +	struct drm_bridge bridge;
> +	struct drm_connector connector;
> +	struct regulator *regulator;
> +	struct drm_panel *panel;
> +	bool pre_enabled;
> +	int error;
> +};
> +
> +static int tc358762_clear_error(struct tc358762 *ctx)
> +{
> +	int ret = ctx->error;
> +
> +	ctx->error = 0;
> +	return ret;
> +}
> +
> +static void tc358762_write(struct tc358762 *ctx, u16 addr, u32 val)
> +{
> +	struct mipi_dsi_device *dsi = to_mipi_dsi_device(ctx->dev);
> +	ssize_t ret;
> +	u8 data[6];
> +
> +	if (ctx->error)
> +		return;
> +
> +	data[0] = addr;
> +	data[1] = addr >> 8;
> +	data[2] = val;
> +	data[3] = val >> 8;
> +	data[4] = val >> 16;
> +	data[5] = val >> 24;
> +
> +	ret = mipi_dsi_generic_write(dsi, data, sizeof(data));
> +	if (ret < 0)
> +		ctx->error = ret;
> +}
> +
> +static inline struct tc358762 *bridge_to_tc358762(struct drm_bridge *bridge)
> +{
> +	return container_of(bridge, struct tc358762, bridge);
> +}
> +
> +static inline
> +struct tc358762 *connector_to_tc358762(struct drm_connector *connector)
> +{
> +	return container_of(connector, struct tc358762, connector);
> +}
> +
> +static int tc358762_init(struct tc358762 *ctx)
> +{
> +	tc358762_write(ctx, DSI_LANEENABLE,
> +		       LANEENABLE_L0EN | LANEENABLE_CLEN);
> +	tc358762_write(ctx, PPI_D0S_CLRSIPOCOUNT, 5);
> +	tc358762_write(ctx, PPI_D1S_CLRSIPOCOUNT, 5);
> +	tc358762_write(ctx, PPI_D0S_ATMR, 0);
> +	tc358762_write(ctx, PPI_D1S_ATMR, 0);
> +	tc358762_write(ctx, PPI_LPTXTIMECNT, LPX_PERIOD);
> +
> +	tc358762_write(ctx, SPICMR, 0x00);
> +	tc358762_write(ctx, LCDCTRL, 0x00100150);
> +	tc358762_write(ctx, SYSCTRL, 0x040f);
> +	msleep(100);
> +
> +	tc358762_write(ctx, PPI_STARTPPI, PPI_START_FUNCTION);
> +	tc358762_write(ctx, DSI_STARTDSI, DSI_RX_START);
> +
> +	msleep(100);
> +
> +	return tc358762_clear_error(ctx);
> +}
> +
> +static int tc358762_get_modes(struct drm_connector *connector)
> +{
> +	struct tc358762 *ctx = connector_to_tc358762(connector);
> +
> +	return drm_panel_get_modes(ctx->panel, connector);
> +}
> +
> +static const
> +struct drm_connector_helper_funcs tc358762_connector_helper_funcs = {
> +	.get_modes = tc358762_get_modes,
> +};
> +
> +static const struct drm_connector_funcs tc358762_connector_funcs = {
> +	.fill_modes = drm_helper_probe_single_connector_modes,
> +	.destroy = drm_connector_cleanup,
> +	.reset = drm_atomic_helper_connector_reset,
> +	.atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
> +	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
> +};
> +
> +static void tc358762_disable(struct drm_bridge *bridge)
> +{
> +	struct tc358762 *ctx = bridge_to_tc358762(bridge);
> +	int ret = drm_panel_disable(bridge_to_tc358762(bridge)->panel);
> +
> +	if (ret < 0)
> +		dev_err(ctx->dev, "error disabling panel (%d)\n", ret);
> +}
> +
> +static void tc358762_post_disable(struct drm_bridge *bridge)
> +{
> +	struct tc358762 *ctx = bridge_to_tc358762(bridge);
> +	int ret;
> +
> +	/*
> +	 * The post_disable hook might be called multiple times.
> +	 * We want to avoid regulator imbalance below.
> +	 */
> +	if (!ctx->pre_enabled)
> +		return;
> +
> +	ctx->pre_enabled = false;
> +
> +	ret = drm_panel_unprepare(ctx->panel);
> +	if (ret < 0)
> +		dev_err(ctx->dev, "error unpreparing panel (%d)\n", ret);
> +
> +	ret = regulator_disable(ctx->regulator);
> +	if (ret < 0)
> +		dev_err(ctx->dev, "error disabling regulators (%d)\n", ret);
> +}
> +
> +static void tc358762_pre_enable(struct drm_bridge *bridge)
> +{
> +	struct tc358762 *ctx = bridge_to_tc358762(bridge);
> +	int ret;
> +
> +	ret = regulator_enable(ctx->regulator);
> +	if (ret < 0)
> +		dev_err(ctx->dev, "error enabling regulators (%d)\n", ret);
> +
> +	ret = tc358762_init(ctx);
> +	if (ret < 0)
> +		dev_err(ctx->dev, "error initializing bridge (%d)\n", ret);
> +
> +	ret = drm_panel_prepare(ctx->panel);
> +	if (ret < 0)
> +		dev_err(ctx->dev, "error preparing panel (%d)\n", ret);
> +
> +	ctx->pre_enabled = true;
> +}
> +
> +static void tc358762_enable(struct drm_bridge *bridge)
> +{
> +	struct tc358762 *ctx = bridge_to_tc358762(bridge);
> +	int ret = drm_panel_enable(ctx->panel);
> +
> +	if (ret < 0)
> +		dev_err(ctx->dev, "error enabling panel (%d)\n", ret);
> +}
> +
> +static int tc358762_attach(struct drm_bridge *bridge,
> +			   enum drm_bridge_attach_flags flags)
> +{
> +	struct tc358762 *ctx = bridge_to_tc358762(bridge);
> +	struct drm_device *drm = bridge->dev;
> +	int ret;
> +
> +	ret = drm_connector_init(drm, &ctx->connector,
> +				 &tc358762_connector_funcs,
> +				 DRM_MODE_CONNECTOR_DPI);
> +	if (ret) {
> +		DRM_ERROR("Failed to initialize connector\n");
> +		return ret;
> +	}
> +
> +	drm_connector_helper_add(&ctx->connector,
> +				 &tc358762_connector_helper_funcs);
> +	drm_connector_attach_encoder(&ctx->connector, bridge->encoder);
> +	drm_panel_attach(ctx->panel, &ctx->connector);
> +	ctx->connector.funcs->reset(&ctx->connector);
> +	drm_connector_register(&ctx->connector);
> +
> +	return 0;
> +}
> +
> +static void tc358762_detach(struct drm_bridge *bridge)
> +{
> +	struct tc358762 *ctx = bridge_to_tc358762(bridge);
> +
> +	drm_connector_unregister(&ctx->connector);
> +	drm_panel_detach(ctx->panel);
> +	ctx->panel = NULL;
> +	drm_connector_put(&ctx->connector);
> +}
> +
> +static const struct drm_bridge_funcs tc358762_bridge_funcs = {
> +	.disable = tc358762_disable,
> +	.post_disable = tc358762_post_disable,
> +	.enable = tc358762_enable,
> +	.pre_enable = tc358762_pre_enable,
> +	.attach = tc358762_attach,
> +	.detach = tc358762_detach,
> +};
> +
> +static int tc358762_parse_dt(struct tc358762 *ctx)
> +{
> +	struct device *dev = ctx->dev;
> +	int ret;
> +
> +	ret = drm_of_find_panel_or_bridge(ctx->dev->of_node, 1, 0, &ctx->panel,
> +					  NULL);
> +	if (ret && ret != -EPROBE_DEFER)
> +		dev_err(dev, "cannot find panel (%d)\n", ret);
> +
> +	return ret;
> +}
> +
> +static int tc358762_configure_regulators(struct tc358762 *ctx)
> +{
> +	ctx->regulator = devm_regulator_get(ctx->dev, "vddc");
> +	if (IS_ERR(ctx->regulator))
> +		return PTR_ERR(ctx->regulator);
> +
> +	return 0;
> +}
> +
> +static int tc358762_probe(struct mipi_dsi_device *dsi)
> +{
> +	struct device *dev = &dsi->dev;
> +	struct tc358762 *ctx;
> +	int ret;
> +
> +	ctx = devm_kzalloc(dev, sizeof(struct tc358762), GFP_KERNEL);
> +	if (!ctx)
> +		return -ENOMEM;
> +
> +	mipi_dsi_set_drvdata(dsi, ctx);
> +
> +	ctx->dev = dev;
> +	ctx->pre_enabled = false;
> +
> +	/* TODO: Find out how to get dual-lane mode working */
> +	dsi->lanes = 1;
> +	dsi->format = MIPI_DSI_FMT_RGB888;
> +	dsi->mode_flags = MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_VIDEO_SYNC_PULSE |
> +			  MIPI_DSI_MODE_LPM;
> +
> +	ret = tc358762_parse_dt(ctx);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = tc358762_configure_regulators(ctx);
> +	if (ret < 0)
> +		return ret;
> +
> +	ctx->bridge.funcs = &tc358762_bridge_funcs;
> +	ctx->bridge.of_node = dev->of_node;
> +
> +	drm_bridge_add(&ctx->bridge);
> +
> +	ret = mipi_dsi_attach(dsi);
> +	if (ret < 0) {
> +		drm_bridge_remove(&ctx->bridge);
> +		dev_err(dev, "failed to attach dsi\n");
> +	}
> +
> +	return ret;
> +}
> +
> +static int tc358762_remove(struct mipi_dsi_device *dsi)
> +{
> +	struct tc358762 *ctx = mipi_dsi_get_drvdata(dsi);
> +
> +	mipi_dsi_detach(dsi);
> +	drm_bridge_remove(&ctx->bridge);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id tc358762_of_match[] = {
> +	{ .compatible = "toshiba,tc358762" },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, tc358762_of_match);
> +
> +static struct mipi_dsi_driver tc358762_driver = {
> +	.probe = tc358762_probe,
> +	.remove = tc358762_remove,
> +	.driver = {
> +		.name = "tc358762",
> +		.of_match_table = tc358762_of_match,
> +	},
> +};
> +module_mipi_dsi_driver(tc358762_driver);
> +
> +MODULE_AUTHOR("Marek Vasut <marex@denx.de>");
> +MODULE_DESCRIPTION("MIPI-DSI based Driver for TC358762 DSI/DPI Bridge");
> +MODULE_LICENSE("GPL v2");
> -- 
> 2.27.0
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