From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andrzej Hajda <a.hajda@samsung.com>
Subject: Re: [PATCH 15/15] drm/panel: Add Sharp LQ101R1SX01 support
Date: Mon, 20 Oct 2014 17:56:57 +0200
Message-ID: <544530C9.1070105@samsung.com>
References: <1413195395-3355-1-git-send-email-thierry.reding@gmail.com>
 <1413195395-3355-15-git-send-email-thierry.reding@gmail.com>
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To: Thierry Reding <thierry.reding@gmail.com>, dri-devel@lists.freedesktop.org
Cc: Mark Rutland <mark.rutland@arm.com>, devicetree@vger.kernel.org, Pawel Moll <pawel.moll@arm.com>, Ian Campbell <ijc+devicetree@hellion.org.uk>, Rob Herring <robh+dt@kernel.org>, Kumar Gala <galak@codeaurora.org>
List-Id: devicetree@vger.kernel.org

On 10/13/2014 12:16 PM, Thierry Reding wrote:
> From: Thierry Reding <treding@nvidia.com>
>
> This panel requires dual-channel mode. The device accepts command-mode
> data on 8 lanes and will therefore need a dual-channel DSI controller.
> The two interfaces that make up this device need to be instantiated in
> the controllers that gang up to provide the dual-channel DSI host.
>
> Signed-off-by: Thierry Reding <treding@nvidia.com>
> ---
>  .../bindings/panel/sharp,lq101r1sx01.txt           |  46 +++
>  drivers/gpu/drm/panel/Kconfig                      |  13 +
>  drivers/gpu/drm/panel/Makefile                     |   1 +
>  drivers/gpu/drm/panel/panel-sharp-lq101r1sx01.c    | 426 +++++++++++++++++++++
>  4 files changed, 486 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/panel/sharp,lq101r1sx01.txt
>  create mode 100644 drivers/gpu/drm/panel/panel-sharp-lq101r1sx01.c
>
> diff --git a/Documentation/devicetree/bindings/panel/sharp,lq101r1sx01.txt b/Documentation/devicetree/bindings/panel/sharp,lq101r1sx01.txt
> new file mode 100644
> index 000000000000..4ab4380ddac8
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/panel/sharp,lq101r1sx01.txt
> @@ -0,0 +1,46 @@
> +Sharp Microelectronics 10.1" WQXGA TFT LCD panel
> +
> +This panel requires a dual-channel DSI host to operate. It supports two modes:
> +- left-right: each channel drives the left or right half of the screen
> +- even-odd: each channel drives the even or odd lines of the screen
> +
> +Each of the DSI channels controls a separate DSI peripheral. The peripheral
> +driven by the first link (DSI-LINK1), left or even, is considered the primary
> +peripheral and controls the device. The 'link2' property contains a phandle
> +to the peripheral driven by the second link (DSI-LINK2, right or odd).
> +
> +Note that in video mode the DSI-LINK1 interface always provides the left/even
> +pixels and DSI-LINK2 always provides the right/odd pixels. In command mode it
> +is possible to program either link to drive the left/even or right/odd pixels
> +but for the sake of consistency this binding assumes that the same assignment
> +is chosen as for video mode.
> +
> +Required properties:
> +- compatible: should be "sharp,lq101r1sx01"
> +- link2: phandle to the DSI peripheral on the secondary link. Note that the
> +  presence of this property marks the containing node as DSI-LINK1.
> +- power-supply: phandle of the regulator that provides the supply voltage
> +
> +Optional properties:
> +- backlight: phandle of the backlight device attached to the panel
> +
> +Example:
> +
> +	dsi@54300000 {
> +		panel: panel@0 {
> +			compatible = "sharp,lq101r1sx01";
> +			reg = <0>;
> +
> +			link2 = <&secondary>;
> +
> +			power-supply = <...>;
> +			backlight = <...>;
> +		};
> +	};
> +
> +	dsi@54400000 {
> +		secondary: panel@0 {
> +			compatible = "sharp,lq101r1sx01";
> +			reg = <0>;
> +		};
> +	};

The example does not follow rules above, 2nd node does not contain
required properties.
Maybe it should be clearly stated that power-supply, link2 and backlight
properties can
be present only in LINK1 node; LINK2 node should contain nothing more
than compatible and reg.

I guess if it wouldn't be better if different compatibles could be used
to distinguish LINK1 and LINK2 nodes,
this way you can provide different sets of required/optional properties
for both nodes. As a bonus you can
have different probe/remove/shutdown callback per link.

> diff --git a/drivers/gpu/drm/panel/Kconfig b/drivers/gpu/drm/panel/Kconfig
> index bee9f72b3a93..024e98ef8e4d 100644
> --- a/drivers/gpu/drm/panel/Kconfig
> +++ b/drivers/gpu/drm/panel/Kconfig
> @@ -27,4 +27,17 @@ config DRM_PANEL_S6E8AA0
>  	select DRM_MIPI_DSI
>  	select VIDEOMODE_HELPERS
>  
> +config DRM_PANEL_SHARP_LQ101R1SX01
> +	tristate "Sharp LQ101R1SX01 panel"
> +	depends on OF
> +	depends on DRM_MIPI_DSI
> +	help
> +	  Say Y here if you want to enable support for Sharp LQ101R1SX01
> +	  TFT-LCD modules. The panel has a 2560x1600 resolution and uses
> +	  24 bit RGB per pixel. It provides a dual MIPI DSI interface to
> +	  the host and has a built-in LED backlight.
> +
> +	  To compile this driver as a module, choose M here: the module
> +	  will be called panel-sharp-lq101r1sx01.
> +
>  endmenu
> diff --git a/drivers/gpu/drm/panel/Makefile b/drivers/gpu/drm/panel/Makefile
> index 8b929212fad7..4b2a0430804b 100644
> --- a/drivers/gpu/drm/panel/Makefile
> +++ b/drivers/gpu/drm/panel/Makefile
> @@ -1,3 +1,4 @@
>  obj-$(CONFIG_DRM_PANEL_SIMPLE) += panel-simple.o
>  obj-$(CONFIG_DRM_PANEL_LD9040) += panel-ld9040.o
>  obj-$(CONFIG_DRM_PANEL_S6E8AA0) += panel-s6e8aa0.o
> +obj-$(CONFIG_DRM_PANEL_SHARP_LQ101R1SX01) += panel-sharp-lq101r1sx01.o
> diff --git a/drivers/gpu/drm/panel/panel-sharp-lq101r1sx01.c b/drivers/gpu/drm/panel/panel-sharp-lq101r1sx01.c
> new file mode 100644
> index 000000000000..09356697d22f
> --- /dev/null
> +++ b/drivers/gpu/drm/panel/panel-sharp-lq101r1sx01.c
> @@ -0,0 +1,426 @@
> +/*
> + * Copyright (C) 2014 NVIDIA Corporation
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#include <linux/backlight.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/regulator/consumer.h>
> +
> +#include <drm/drmP.h>
> +#include <drm/drm_crtc.h>
> +#include <drm/drm_mipi_dsi.h>
> +#include <drm/drm_panel.h>
> +
> +#include <video/mipi_display.h>
> +
> +#include <linux/host1x.h>
> +
> +struct sharp_panel {
> +	struct drm_panel base;
> +	/* the datasheet refers to them as DSI-LINK1 and DSI-LINK2 */
> +	struct mipi_dsi_device *link1;
> +	struct mipi_dsi_device *link2;
> +
> +	struct backlight_device *backlight;
> +	struct regulator *supply;
> +
> +	bool prepared;
> +	bool enabled;
> +
> +	const struct drm_display_mode *mode;
> +};
> +
> +static inline struct sharp_panel *to_sharp_panel(struct drm_panel *panel)
> +{
> +	return container_of(panel, struct sharp_panel, base);
> +}
> +
> +static int sharp_panel_write(struct sharp_panel *sharp, u16 offset, u8 value)
> +{
> +	u8 payload[3] = { offset >> 8, offset & 0xff, value };
> +	struct mipi_dsi_device *dsi = sharp->link1;
> +	ssize_t err;
> +
> +	err = mipi_dsi_generic_write(dsi, payload, sizeof(payload));
> +	if (err < 0)
> +		dev_err(&dsi->dev, "failed to write %02x to %04x: %d\n",
> +			value, offset, err);
> +
> +	err = mipi_dsi_dcs_nop(dsi);
> +	if (err < 0)
> +		dev_err(&dsi->dev, "failed to send DCS nop: %d\n", err);
> +

If mipi_dsi_generic_write fails and mipi_dsi_dcs_nop succeeds function
return success, is it OK?

> +	usleep_range(10, 20);
> +
> +	return err;
> +}
> +
> +static __maybe_unused int sharp_panel_read(struct sharp_panel *sharp,
> +					   u16 offset, u8 *value)
> +{
> +	ssize_t err;
> +
> +	cpu_to_be16s(&offset);
> +
> +	err = mipi_dsi_generic_read(sharp->link1, &offset, sizeof(offset),
> +				    value, sizeof(*value));
> +	if (err < 0)
> +		dev_err(&sharp->link1->dev, "failed to read from %04x: %d\n",
> +			offset, err);
> +
> +	return err;
> +}
> +
> +static int sharp_panel_disable(struct drm_panel *panel)
> +{
> +	struct sharp_panel *sharp = to_sharp_panel(panel);
> +
> +	if (!sharp->enabled)
> +		return 0;

Shouldn't we assume disable callback can be called only on enabled panel?

> +
> +	if (sharp->backlight) {
> +		sharp->backlight->props.power = FB_BLANK_POWERDOWN;
> +		backlight_update_status(sharp->backlight);
> +	}
> +
> +	sharp->enabled = false;
> +
> +	return 0;
> +}
> +
> +static int sharp_panel_unprepare(struct drm_panel *panel)
> +{
> +	struct sharp_panel *sharp = to_sharp_panel(panel);
> +	int err;
> +
> +	if (!sharp->prepared)
> +		return 0;

Shouldn't we assume unprepare callback can be called only on enabled panel?

> +
> +	err = mipi_dsi_dcs_set_display_off(sharp->link1);
> +	if (err < 0)
> +		dev_err(panel->dev, "failed to set display off: %d\n", err);
> +
> +	err = mipi_dsi_dcs_enter_sleep_mode(sharp->link1);
> +	if (err < 0)
> +		dev_err(panel->dev, "failed to enter sleep mode: %d\n", err);
> +
> +	msleep(120);
> +
> +	regulator_disable(sharp->supply);
> +
> +	sharp->prepared = false;
> +
> +	return 0;
> +}
> +
> +static int sharp_setup_symmetrical_split(struct mipi_dsi_device *left,
> +					 struct mipi_dsi_device *right,
> +					 const struct drm_display_mode *mode)
> +{
> +	int err;
> +
> +	err = mipi_dsi_dcs_set_column_address(left, 0, mode->hdisplay / 2 - 1);
> +	if (err < 0)
> +		dev_err(&left->dev, "failed to set column address: %d\n", err);
> +
> +	err = mipi_dsi_dcs_set_page_address(left, 0, mode->vdisplay - 1);
> +	if (err < 0)
> +		dev_err(&left->dev, "failed to set page address: %d\n", err);
> +
> +	err = mipi_dsi_dcs_set_column_address(right, mode->hdisplay / 2,
> +					      mode->hdisplay - 1);
> +	if (err < 0)
> +		dev_err(&right->dev, "failed to set column address: %d\n", err);
> +
> +	err = mipi_dsi_dcs_set_page_address(right, 0, mode->vdisplay - 1);
> +	if (err < 0)
> +		dev_err(&right->dev, "failed to set page address: %d\n", err);
> +
> +	return 0;

It always returns 0, maybe it could be void?

> +}
> +
> +static int sharp_panel_prepare(struct drm_panel *panel)
> +{
> +	struct sharp_panel *sharp = to_sharp_panel(panel);
> +	u8 format = MIPI_DCS_PIXEL_FMT_24BIT;
> +	int err;
> +
> +	if (sharp->prepared)
> +		return 0;
> +
> +	err = regulator_enable(sharp->supply);
> +	if (err < 0)
> +		return err;
> +
> +	usleep_range(10000, 20000);
> +
> +	err = mipi_dsi_dcs_soft_reset(sharp->link1);
> +	if (err < 0)
> +		dev_err(panel->dev, "soft reset failed: %d\n", err);
> +
> +	msleep(120);
> +
> +	err = mipi_dsi_dcs_exit_sleep_mode(sharp->link1);
> +	if (err < 0)
> +		dev_err(panel->dev, "failed to exit sleep mode: %d\n", err);
> +
> +	/*
> +	 * The MIPI DCS specification mandates this delay only between the
> +	 * exit_sleep_mode and enter_sleep_mode commands, so it isn't strictly
> +	 * necessary here.
> +	 */
> +	/*
> +	msleep(120);
> +	*/
> +
> +	/* set left-right mode */
> +	err = sharp_panel_write(sharp, 0x1000, 0x2a);
> +	if (err < 0)
> +		dev_err(panel->dev, "failed to set left-right mode: %d\n", err);
> +
> +	/* enable command mode */
> +	err = sharp_panel_write(sharp, 0x1001, 0x01);
> +	if (err < 0)
> +		dev_err(panel->dev, "failed to enable command mode: %d\n", err);
> +
> +	err = mipi_dsi_dcs_set_pixel_format(sharp->link1, format);
> +	if (err < 0)
> +		dev_err(panel->dev, "failed to set pixel format: %d\n", err);
> +
> +	/*
> +	 * TODO: The device supports both left-right and even-odd split
> +	 * configurations, but this driver currently supports only the left-
> +	 * right split. To support a different mode a mechanism needs to be
> +	 * put in place to communicate the configuration back to the DSI host
> +	 * controller.
> +	 */
> +	err = sharp_setup_symmetrical_split(sharp->link1, sharp->link2,
> +					    sharp->mode);
> +	if (err < 0)
> +		dev_err(panel->dev, "failed to set up symmetrical split: %d\n",
> +			err);
> +
> +	err = mipi_dsi_dcs_set_display_on(sharp->link1);
> +	if (err < 0)
> +		dev_err(panel->dev, "failed to set display on: %d\n", err);
> +
> +	sharp->prepared = true;
> +
> +	return err;

You should return 0 here, or if you want to signal error to caller you
should unwind
changes, I guess regulator_disable should be enough.

> +}
> +
> +static int sharp_panel_enable(struct drm_panel *panel)
> +{
> +	struct sharp_panel *sharp = to_sharp_panel(panel);
> +
> +	if (sharp->enabled)
> +		return 0;
> +
> +	if (sharp->backlight) {
> +		sharp->backlight->props.power = FB_BLANK_UNBLANK;
> +		backlight_update_status(sharp->backlight);
> +	}
> +
> +	sharp->enabled = true;
> +
> +	return 0;
> +}
> +
> +static const struct drm_display_mode default_mode = {
> +	.clock = 278000,
> +	.hdisplay = 2560,
> +	.hsync_start = 2560 + 128,
> +	.hsync_end = 2560 + 128 + 64,
> +	.htotal = 2560 + 128 + 64 + 64,
> +	.vdisplay = 1600,
> +	.vsync_start = 1600 + 4,
> +	.vsync_end = 1600 + 4 + 8,
> +	.vtotal = 1600 + 4 + 8 + 32,
> +	.vrefresh = 60,
> +};
> +
> +static int sharp_panel_get_modes(struct drm_panel *panel)
> +{
> +	struct drm_display_mode *mode;
> +
> +	mode = drm_mode_duplicate(panel->drm, &default_mode);
> +	if (!mode) {
> +		dev_err(panel->drm->dev, "failed to add mode %ux%ux@%u\n",
> +			default_mode.hdisplay, default_mode.vdisplay,
> +			default_mode.vrefresh);
> +		return -ENOMEM;
> +	}
> +
> +	drm_mode_set_name(mode);
> +
> +	drm_mode_probed_add(panel->connector, mode);
> +
> +	panel->connector->display_info.width_mm = 217;
> +	panel->connector->display_info.height_mm = 136;
> +
> +	return 1;
> +}
> +
> +static const struct drm_panel_funcs sharp_panel_funcs = {
> +	.disable = sharp_panel_disable,
> +	.unprepare = sharp_panel_unprepare,
> +	.prepare = sharp_panel_prepare,
> +	.enable = sharp_panel_enable,
> +	.get_modes = sharp_panel_get_modes,
> +};
> +
> +static const struct of_device_id sharp_of_match[] = {
> +	{ .compatible = "sharp,lq101r1sx01", },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, sharp_of_match);
> +
> +static int sharp_panel_add(struct sharp_panel *sharp)
> +{
> +	struct device_node *np;
> +	int err;
> +
> +	sharp->mode = &default_mode;
> +
> +	sharp->supply = devm_regulator_get(&sharp->link1->dev, "power");
> +	if (IS_ERR(sharp->supply))
> +		return PTR_ERR(sharp->supply);
> +
> +	np = of_parse_phandle(sharp->link1->dev.of_node, "backlight", 0);
> +	if (np) {
> +		sharp->backlight = of_find_backlight_by_node(np);
> +		of_node_put(np);
> +
> +		if (!sharp->backlight)
> +			return -EPROBE_DEFER;
> +	}
> +
> +	drm_panel_init(&sharp->base);
> +	sharp->base.funcs = &sharp_panel_funcs;
> +	sharp->base.dev = &sharp->link1->dev;
> +
> +	err = drm_panel_add(&sharp->base);
> +	if (err < 0)
> +		goto put_backlight;
> +
> +	return 0;
> +
> +put_backlight:
> +	if (sharp->backlight)
> +		put_device(&sharp->backlight->dev);
> +
> +	return err;
> +}
> +
> +static void sharp_panel_del(struct sharp_panel *sharp)
> +{
> +	if (sharp->base.dev)
> +		drm_panel_remove(&sharp->base);
> +
> +	if (sharp->backlight)
> +		put_device(&sharp->backlight->dev);
> +}
> +
> +static int sharp_panel_probe(struct mipi_dsi_device *dsi)
> +{
> +	struct mipi_dsi_device *secondary = NULL;
> +	struct sharp_panel *sharp;
> +	struct device_node *np;
> +	int err;
> +
> +	dsi->lanes = 4;
> +	dsi->format = MIPI_DSI_FMT_RGB888;
> +	dsi->mode_flags = 0;
> +
> +	/* Find DSI-LINK1 */
> +	np = of_parse_phandle(dsi->dev.of_node, "link2", 0);
> +	if (np) {
> +		secondary = of_find_mipi_dsi_device_by_node(np);
> +		of_node_put(np);
> +
> +		if (!secondary)
> +			return -EPROBE_DEFER;
> +	}
> +
> +	sharp = devm_kzalloc(&dsi->dev, sizeof(*sharp), GFP_KERNEL);
> +	if (!sharp)
> +		return -ENOMEM;

Do we really need this for LINK2 device? You can just check if
mipi_dsi_get_drvdata
is not null to distinguish them, I suppose.

> +
> +	mipi_dsi_set_drvdata(dsi, sharp);
> +
> +	/* register a panel for only the DSI-LINK1 interface */
> +	if (secondary) {
> +		sharp->link2 = secondary;
> +		sharp->link1 = dsi;
> +
> +		err = sharp_panel_add(sharp);
> +		if (err < 0)
> +			return err;
> +	}
> +
> +	err = mipi_dsi_attach(dsi);
> +	if (err < 0) {
> +		sharp_panel_del(sharp);
> +		return err;
> +	}
> +
> +	return 0;
> +}
> +
> +static int sharp_panel_remove(struct mipi_dsi_device *dsi)
> +{
> +	struct sharp_panel *sharp = mipi_dsi_get_drvdata(dsi);
> +	int err;
> +
> +	/* only detach from host for the DSI-LINK2 interface */
> +	if (!sharp->link2) {
> +		mipi_dsi_detach(dsi);

There is no locking mechanism here, so it is possible that
everything can crash if someone unbind driver from LINK2 and then try to
enable the panel.

> +		return 0;
> +	}
> +
> +	err = sharp_panel_disable(&sharp->base);
> +	if (err < 0)
> +		dev_err(&dsi->dev, "failed to disable panel: %d\n", err);

IMHO calling mipi_dsi_detach below should cause connector to call panel
disable and unprepare so the call above seems to me unnecessary.

> +
> +	err = mipi_dsi_detach(dsi);
> +	if (err < 0)
> +		dev_err(&dsi->dev, "failed to detach from DSI host: %d\n", err);
> +
> +	drm_panel_detach(&sharp->base);

drm_panel_attach is called from tegra_dsi_host_attach,
wouldn't be more 'symmetrical' to call drm_panel_detach from
tegra_dsi_host_detach :)

Regards
Andrzej

> +	drm_panel_remove(&sharp->base);
> +
> +	if (sharp->backlight)
> +		put_device(&sharp->backlight->dev);
> +
> +	put_device(&sharp->link2->dev);
> +
> +	return 0;
> +}
> +
> +static void sharp_panel_shutdown(struct mipi_dsi_device *dsi)
> +{
> +	struct sharp_panel *sharp = mipi_dsi_get_drvdata(dsi);
> +
> +	sharp_panel_disable(&sharp->base);
> +}
> +
> +static struct mipi_dsi_driver sharp_panel_driver = {
> +	.driver = {
> +		.name = "panel-sharp-lq101r1sx01",
> +		.of_match_table = sharp_of_match,
> +	},
> +	.probe = sharp_panel_probe,
> +	.remove = sharp_panel_remove,
> +	.shutdown = sharp_panel_shutdown,
> +};
> +module_mipi_dsi_driver(sharp_panel_driver);
> +
> +MODULE_AUTHOR("Thierry Reding <treding@nvidia.com>");
> +MODULE_DESCRIPTION("Sharp LQ101R1SX01 panel driver");
> +MODULE_LICENSE("GPL v2");