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Date:   Sun, 17 Mar 2019 18:30:01 +0200
From:   Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To:     Maxime Ripard <maxime.ripard@bootlin.com>
Cc:     Jagan Teki <jagan@amarulasolutions.com>,
        Andrzej Hajda <a.hajda@samsung.com>,
        Chen-Yu Tsai <wens@csie.org>, David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        Rob Herring <robh+dt@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Michael Trimarchi <michael@amarulasolutions.com>,
        dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org,
        devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-sunxi@googlegroups.com, linux-amarula@amarulasolutions.com
Subject: Re: [PATCH 5/6] drm/bridge: Add Chipone ICN6211 MIPI-DSI/RGB
 convertor bridge
Message-ID: <20190317163001.GE17898@pendragon.ideasonboard.com>
References: <20190315130825.9005-1-jagan@amarulasolutions.com>
 <20190315130825.9005-6-jagan@amarulasolutions.com>
 <20190315133304.vzwy3tbw27e6lum3@flea>
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Hello,

On Fri, Mar 15, 2019 at 02:33:04PM +0100, Maxime Ripard wrote:
> On Fri, Mar 15, 2019 at 06:38:24PM +0530, Jagan Teki wrote:
> > ICN6211 is MIPI-DSI/RGB converter bridge from chipone.
> > It has a flexible configuration of MIPI DSI signal input
> > and produce RGB565, RGB666, RGB888 output format.
> > 
> > Add bridge driver for it.
> > 
> > Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
> > ---
> >  MAINTAINERS                              |   6 +
> >  drivers/gpu/drm/bridge/Kconfig           |  10 +
> >  drivers/gpu/drm/bridge/Makefile          |   1 +
> >  drivers/gpu/drm/bridge/chipone-icn6211.c | 275 +++++++++++++++++++++++
> >  4 files changed, 292 insertions(+)
> >  create mode 100644 drivers/gpu/drm/bridge/chipone-icn6211.c
> > 
> > diff --git a/MAINTAINERS b/MAINTAINERS
> > index 4de80222cffb..e529addd30f5 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -4897,6 +4897,12 @@ T:	git git://anongit.freedesktop.org/drm/drm-misc
> >  S:	Maintained
> >  F:	drivers/gpu/drm/bochs/
> >  
> > +DRM DRIVER FOR CHIPONE ICN6211 MIPI-DSI to RGB CONVERTOR BRIDGE
> > +M:	Jagan Teki <jagan@amarulasolutions.com>
> > +S:	Maintained
> > +F:	drivers/gpu/drm/bridge/chipone-icn6211.c
> > +F:	Documentation/devicetree/bindings/display/bridge/chipone,icn6211.txt
> > +
> >  DRM DRIVER FOR FARADAY TVE200 TV ENCODER
> >  M:	Linus Walleij <linus.walleij@linaro.org>
> >  T:	git git://anongit.freedesktop.org/drm/drm-misc
> > diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
> > index 8840f396a7b6..cd314572e4ed 100644
> > --- a/drivers/gpu/drm/bridge/Kconfig
> > +++ b/drivers/gpu/drm/bridge/Kconfig
> > @@ -36,6 +36,16 @@ config DRM_CDNS_DSI
> >  	  Support Cadence DPI to DSI bridge. This is an internal
> >  	  bridge and is meant to be directly embedded in a SoC.
> >  
> > +config DRM_CHIPONE_ICN6211
> > +	tristate "Chipone ICN6211 MIPI-DSI/RGB converter bridge"
> > +	depends on DRM && DRM_PANEL
> > +	depends on OF
> > +	select DRM_MIPI_DSI
> > +	help
> > +	  ICN6211 is MIPI-DSI/RGB converter bridge from chipone.
> > +	  It has a flexible configuration of MIPI DSI signal input
> > +	  and produce RGB565, RGB666, RGB888 output format.
> > +
> >  config DRM_DUMB_VGA_DAC
> >  	tristate "Dumb VGA DAC Bridge support"
> >  	depends on OF
> > diff --git a/drivers/gpu/drm/bridge/Makefile b/drivers/gpu/drm/bridge/Makefile
> > index 4934fcf5a6f8..541fdccad10b 100644
> > --- a/drivers/gpu/drm/bridge/Makefile
> > +++ b/drivers/gpu/drm/bridge/Makefile
> > @@ -1,6 +1,7 @@
> >  # SPDX-License-Identifier: GPL-2.0
> >  obj-$(CONFIG_DRM_ANALOGIX_ANX78XX) += analogix-anx78xx.o
> >  obj-$(CONFIG_DRM_CDNS_DSI) += cdns-dsi.o
> > +obj-$(CONFIG_DRM_CHIPONE_ICN6211) += chipone-icn6211.o
> >  obj-$(CONFIG_DRM_DUMB_VGA_DAC) += dumb-vga-dac.o
> >  obj-$(CONFIG_DRM_LVDS_ENCODER) += lvds-encoder.o
> >  obj-$(CONFIG_DRM_MEGACHIPS_STDPXXXX_GE_B850V3_FW) += megachips-stdpxxxx-ge-b850v3-fw.o
> > diff --git a/drivers/gpu/drm/bridge/chipone-icn6211.c b/drivers/gpu/drm/bridge/chipone-icn6211.c
> > new file mode 100644
> > index 000000000000..cd2f3505f845
> > --- /dev/null
> > +++ b/drivers/gpu/drm/bridge/chipone-icn6211.c
> > @@ -0,0 +1,275 @@
> > +// SPDX-License-Identifier: GPL-2.0+
> > +/*
> > + * Copyright (C) 2018 Amarula Solutions
> > + * Author: Jagan Teki <jagan@amarulasolutions.com>
> > + */
> > +
> > +#include <drm/drm_atomic_helper.h>
> > +#include <drm/drm_fb_helper.h>
> > +#include <drm/drm_of.h>
> > +#include <drm/drm_panel.h>
> > +#include <drm/drm_print.h>
> > +#include <drm/drm_probe_helper.h>
> > +#include <drm/drm_mipi_dsi.h>
> > +
> > +#include <linux/delay.h>
> > +#include <linux/gpio/consumer.h>
> > +#include <linux/module.h>
> > +#include <linux/of_graph.h>
> > +
> > +#define ICN6211_INIT_CMD_LEN		2
> > +
> > +struct chipone {
> > +	struct device *dev;
> > +	struct drm_bridge bridge;
> > +	struct drm_connector connector;
> > +	struct drm_panel *panel;
> > +
> > +	struct gpio_desc *reset;
> > +};
> > +
> > +static inline struct chipone *bridge_to_chipone(struct drm_bridge *bridge)
> > +{
> > +	return container_of(bridge, struct chipone, bridge);
> > +}
> > +
> > +static inline
> > +struct chipone *connector_to_chipone(struct drm_connector *connector)
> > +{
> > +	return container_of(connector, struct chipone, connector);
> > +}
> > +
> > +struct icn6211_init_cmd {
> > +	u8 data[ICN6211_INIT_CMD_LEN];
> > +};
> > +
> > +static const struct icn6211_init_cmd icn6211_init_cmds[] = {
> > +	{ .data = { 0x7A, 0xC1 } },
> > +	{ .data = { 0x20, 0x20 } },
> > +	{ .data = { 0x21, 0xE0 } },
> > +	{ .data = { 0x22, 0x13 } },
> > +	{ .data = { 0x23, 0x28 } },
> > +	{ .data = { 0x24, 0x30 } },
> > +	{ .data = { 0x25, 0x28 } },
> > +	{ .data = { 0x26, 0x00 } },
> > +	{ .data = { 0x27, 0x0D } },
> > +	{ .data = { 0x28, 0x03 } },
> > +	{ .data = { 0x29, 0x1D } },
> > +	{ .data = { 0x34, 0x80 } },
> > +	{ .data = { 0x36, 0x28 } },
> > +	{ .data = { 0xB5, 0xA0 } },
> > +	{ .data = { 0x5C, 0xFF } },
> > +	{ .data = { 0x2A, 0x01 } },
> > +	{ .data = { 0x56, 0x92 } },
> > +	{ .data = { 0x6B, 0x71 } },
> > +	{ .data = { 0x69, 0x2B } },
> > +	{ .data = { 0x10, 0x40 } },
> > +	{ .data = { 0x11, 0x98 } },
> > +	{ .data = { 0xB6, 0x20 } },
> > +	{ .data = { 0x51, 0x20 } },
> > +	{ .data = { 0x09, 0x10 } },
> > +};
> 
> What are those commands supposed to be? Some of them at least look
> pretty standard (and have proper functions):
> MIPI_DCS_EXIT_INVERT_MODE, _SET_DISPLAY_ON, _SET_TEAR_OFF, etc.
> 
> > +static int chipone_get_modes(struct drm_connector *connector)
> > +{
> > +	struct chipone *icn = connector_to_chipone(connector);
> > +
> > +	return drm_panel_get_modes(icn->panel);
> > +}
> > +
> > +static const
> > +struct drm_connector_helper_funcs chipone_connector_helper_funcs = {
> > +	.get_modes = chipone_get_modes,
> > +};
> > +
> > +static const struct drm_connector_funcs chipone_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 chipone_disable(struct drm_bridge *bridge)
> > +{
> > +	struct chipone *icn = bridge_to_chipone(bridge);
> > +	int ret = drm_panel_disable(bridge_to_chipone(bridge)->panel);
> > +
> > +	if (ret < 0)
> > +		DRM_DEV_ERROR(icn->dev, "error disabling panel (%d)\n", ret);
> > +}
> > +
> > +static void chipone_post_disable(struct drm_bridge *bridge)
> > +{
> > +	struct chipone *icn = bridge_to_chipone(bridge);
> > +	int ret;
> > +
> > +	ret = drm_panel_unprepare(icn->panel);
> > +	if (ret < 0)
> > +		DRM_DEV_ERROR(icn->dev, "error unpreparing panel (%d)\n", ret);
> > +
> > +	msleep(50);
> > +
> > +	gpiod_set_value(icn->reset, 0);
> > +}
> > +
> > +static void chipone_pre_enable(struct drm_bridge *bridge)
> > +{
> > +	struct chipone *icn = bridge_to_chipone(bridge);
> > +	struct mipi_dsi_device *dsi = to_mipi_dsi_device(icn->dev);
> > +	unsigned int i;
> > +	int ret;
> > +
> > +	gpiod_set_value(icn->reset, 0);
> > +	msleep(20);
> > +
> > +	gpiod_set_value(icn->reset, 1);
> > +	msleep(50);
> > +
> > +	for (i = 0; i < ARRAY_SIZE(icn6211_init_cmds); i++) {
> > +		const struct icn6211_init_cmd *cmd = &icn6211_init_cmds[i];
> > +
> > +		ret = mipi_dsi_generic_write(dsi, cmd->data,
> > +					     ICN6211_INIT_CMD_LEN);
> > +		if (ret < 0) {
> > +			DRM_DEV_ERROR(icn->dev,
> > +				      "failed to write cmd %d: %d\n", i, ret);
> > +			return;
> > +		}
> > +	}
> > +
> > +	ret = drm_panel_prepare(icn->panel);
> > +	if (ret < 0)
> > +		DRM_DEV_ERROR(icn->dev, "error preparing panel (%d)\n", ret);
> > +}
> > +
> > +static void chipone_enable(struct drm_bridge *bridge)
> > +{
> > +	struct chipone *icn = bridge_to_chipone(bridge);
> > +	int ret = drm_panel_enable(icn->panel);
> > +
> > +	if (ret < 0)
> > +		DRM_DEV_ERROR(icn->dev, "error enabling panel (%d)\n", ret);
> > +}
> > +
> > +static int chipone_attach(struct drm_bridge *bridge)
> > +{
> > +	struct chipone *icn = bridge_to_chipone(bridge);
> > +	struct drm_device *drm = bridge->dev;
> > +	int ret;
> > +
> > +	icn->connector.polled = DRM_CONNECTOR_POLL_HPD;
> > +	ret = drm_connector_init(drm, &icn->connector,
> > +				 &chipone_connector_funcs,
> > +				 DRM_MODE_CONNECTOR_Unknown);
> 
> It should be a DRM_MODE_CONNECTOR_DPI connector.

I'd go one step further, the driver should use drm_panel_bridge_add()
and not create a connector itself. It should also support the case where
the RGB output is connected to a bridge instead of a panel.

> > +	if (ret) {
> > +		DRM_ERROR("Failed to initialize connector\n");
> > +		return ret;
> > +	}
> > +
> > +	drm_connector_helper_add(&icn->connector,
> > +				 &chipone_connector_helper_funcs);
> > +	drm_connector_attach_encoder(&icn->connector, bridge->encoder);
> > +	drm_panel_attach(icn->panel, &icn->connector);
> > +	icn->connector.funcs->reset(&icn->connector);
> > +	drm_fb_helper_add_one_connector(drm->fb_helper, &icn->connector);
> 
> What do you need that for?
> 
> > +	drm_connector_register(&icn->connector);
> > +
> > +	return 0;
> > +}
> > +
> > +static void chipone_detach(struct drm_bridge *bridge)
> > +{
> > +	struct chipone *icn = bridge_to_chipone(bridge);
> > +	struct drm_device *drm = bridge->dev;
> > +
> > +	drm_connector_unregister(&icn->connector);
> > +	drm_fb_helper_remove_one_connector(drm->fb_helper, &icn->connector);
> > +	drm_panel_detach(icn->panel);
> > +	icn->panel = NULL;
> > +	drm_connector_put(&icn->connector);
> > +}
> > +
> > +static const struct drm_bridge_funcs chipone_bridge_funcs = {
> > +	.disable = chipone_disable,
> > +	.post_disable = chipone_post_disable,
> > +	.enable = chipone_enable,
> > +	.pre_enable = chipone_pre_enable,
> > +	.attach = chipone_attach,
> > +	.detach = chipone_detach,
> > +};
> > +
> > +static int chipone_probe(struct mipi_dsi_device *dsi)
> > +{
> > +	struct device *dev = &dsi->dev;
> > +	struct chipone *icn;
> > +	int ret;
> > +
> > +	icn = devm_kzalloc(dev, sizeof(struct chipone), GFP_KERNEL);
> > +	if (!icn)
> > +		return -ENOMEM;
> > +
> > +	mipi_dsi_set_drvdata(dsi, icn);
> > +
> > +	icn->dev = dev;
> > +	dsi->lanes = 4;
> > +	dsi->format = MIPI_DSI_FMT_RGB888;
> > +	dsi->mode_flags = MIPI_DSI_MODE_VIDEO_SYNC_PULSE;
> > +
> > +	icn->reset = devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW);
> > +	if (IS_ERR(icn->reset)) {
> > +		DRM_DEV_ERROR(dev, "no reset GPIO pin provided\n");
> > +		return PTR_ERR(icn->reset);
> > +	}
> > +
> > +	ret = drm_of_find_panel_or_bridge(icn->dev->of_node, 1, 0,
> > +					  &icn->panel, NULL);
> > +	if (ret && ret != -EPROBE_DEFER) {
> > +		DRM_DEV_ERROR(dev, "failed to find panel (ret = %d)\n", ret);
> > +		return ret;
> > +	}
> > +
> > +	icn->bridge.funcs = &chipone_bridge_funcs;
> > +	icn->bridge.of_node = dev->of_node;
> > +
> > +	drm_bridge_add(&icn->bridge);
> > +
> > +	ret = mipi_dsi_attach(dsi);
> > +	if (ret < 0) {
> > +		drm_bridge_remove(&icn->bridge);
> > +		DRM_DEV_ERROR(dev, "failed to attach dsi (ret = %d)\n", ret);
> > +	}
> > +
> > +	return ret;
> > +}
> > +
> > +static int chipone_remove(struct mipi_dsi_device *dsi)
> > +{
> > +	struct chipone *icn = mipi_dsi_get_drvdata(dsi);
> > +
> > +	mipi_dsi_detach(dsi);
> > +	drm_bridge_remove(&icn->bridge);
> > +
> > +	return 0;
> > +}
> > +
> > +static const struct of_device_id chipone_of_match[] = {
> > +	{ .compatible = "bananapi,icn6211" },
> 
> This should have your generic compatible listed

-- 
Regards,

Laurent Pinchart