Re: [PATCH v3 7/9] drm/panel: Add driver for the Sony ACX565AKM panel

[Sam Ravnborg <sam@ravnborg.org>]

Hi Laurent.


On Tue, Aug 13, 2019 at 04:33:09PM +0300, Laurent Pinchart wrote:
> This panel is used on the Nokia N900.
> 
> The code is based on the omapdrm-specific panel-sony-acx565akm driver.
> 
> Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

Looking at the backlight support in this driver there is some potential
for using more of the infrastructure.
iFor example there should be no need for acx565akm_panel.mutex,
as the core handles locking.

Backlight should maybe use devm_backlight_device_register()
as part of using more infrastructure, so clean-up is automatic.

Also the implementation of the enable/disable callbacks looks like
most of the implementation belongs in prepare/unprepare callbacks.

And enable() could be as trivial as:

	backlight_update_status(acx565akm_panel->backlight);


My feedback to this patch would be:
"This is how it was in the original driver so we can fix it in a
follow-up patch. Follow-up patch needs HW to test the changes."

If you add a TODO like this:
TODO:
- Update backlight support to use backlight_update_status() etc.
- Use prepare/unprepare for the basic power on/off of the backligt

(Or some other way to remember we need to do this) then:
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>

Even better would be a follow-up patch to actually do these things.

	Sam


> ---
> Changes since v2:
> 
> - Call drm_panel_unprepare() in .remove() handler
> 
> Changes since v1:
> 
> - Mention boards using the panel in Kconfig
> - Renamed acx565akm_device to acx565akm_panel
> - Comments updates
> - Store width_mm and height_mm in drm_display_mode
> - Use drm_panel_disable() in .remove() handler
> ---
>  drivers/gpu/drm/panel/Kconfig                |   8 +
>  drivers/gpu/drm/panel/Makefile               |   1 +
>  drivers/gpu/drm/panel/panel-sony-acx565akm.c | 694 +++++++++++++++++++
>  3 files changed, 703 insertions(+)
>  create mode 100644 drivers/gpu/drm/panel/panel-sony-acx565akm.c
> 
> diff --git a/drivers/gpu/drm/panel/Kconfig b/drivers/gpu/drm/panel/Kconfig
> index 8d9a8cdb704e..b05649b3118a 100644
> --- a/drivers/gpu/drm/panel/Kconfig
> +++ b/drivers/gpu/drm/panel/Kconfig
> @@ -316,6 +316,14 @@ config DRM_PANEL_SITRONIX_ST7789V
>  	  Say Y here if you want to enable support for the Sitronix
>  	  ST7789V controller for 240x320 LCD panels
>  
> +config DRM_PANEL_SONY_ACX565AKM
> +	tristate "Sony ACX565AKM panel"
> +	depends on GPIOLIB && OF && SPI
> +	depends on BACKLIGHT_CLASS_DEVICE

> +	help
> +	  Say Y here if you want to enable support for the Sony ACX565AKM
> +	  800x600 3.5" panel (found on the Nokia N900).
> +
>  config DRM_PANEL_TPO_TPG110
>  	tristate "TPO TPG 800x400 panel"
>  	depends on OF && SPI && GPIOLIB
> diff --git a/drivers/gpu/drm/panel/Makefile b/drivers/gpu/drm/panel/Makefile
> index 14d1c49ef3ab..28cf2332fd06 100644
> --- a/drivers/gpu/drm/panel/Makefile
> +++ b/drivers/gpu/drm/panel/Makefile
> @@ -33,5 +33,6 @@ obj-$(CONFIG_DRM_PANEL_SHARP_LS037V7DW01) += panel-sharp-ls037v7dw01.o
>  obj-$(CONFIG_DRM_PANEL_SHARP_LS043T1LE01) += panel-sharp-ls043t1le01.o
>  obj-$(CONFIG_DRM_PANEL_SITRONIX_ST7701) += panel-sitronix-st7701.o
>  obj-$(CONFIG_DRM_PANEL_SITRONIX_ST7789V) += panel-sitronix-st7789v.o
> +obj-$(CONFIG_DRM_PANEL_SONY_ACX565AKM) += panel-sony-acx565akm.o
>  obj-$(CONFIG_DRM_PANEL_TPO_TPG110) += panel-tpo-tpg110.o
>  obj-$(CONFIG_DRM_PANEL_TRULY_NT35597_WQXGA) += panel-truly-nt35597.o
> diff --git a/drivers/gpu/drm/panel/panel-sony-acx565akm.c b/drivers/gpu/drm/panel/panel-sony-acx565akm.c
> new file mode 100644
> index 000000000000..c8c82163e24d
> --- /dev/null
> +++ b/drivers/gpu/drm/panel/panel-sony-acx565akm.c
> @@ -0,0 +1,694 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Sony ACX565AKM LCD Panel driver
> + *
> + * Copyright (C) 2019 Texas Instruments Incorporated
> + *
> + * Based on the omapdrm-specific panel-sony-acx565akm driver
> + *
> + * Copyright (C) 2010 Nokia Corporation
> + * Author: Imre Deak <imre.deak@nokia.com>
> + */
> +
> +#include <linux/backlight.h>
> +#include <linux/delay.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/jiffies.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/sched.h>
> +#include <linux/spi/spi.h>
> +#include <video/mipi_display.h>
> +
> +#include <drm/drm_connector.h>
> +#include <drm/drm_modes.h>
> +#include <drm/drm_panel.h>
> +
> +#define CTRL_DISP_BRIGHTNESS_CTRL_ON		(1 << 5)
> +#define CTRL_DISP_AMBIENT_LIGHT_CTRL_ON		(1 << 4)
> +#define CTRL_DISP_BACKLIGHT_ON			(1 << 2)
> +#define CTRL_DISP_AUTO_BRIGHTNESS_ON		(1 << 1)
> +
> +#define MIPID_CMD_WRITE_CABC		0x55
> +#define MIPID_CMD_READ_CABC		0x56
> +
> +#define MIPID_VER_LPH8923		3
> +#define MIPID_VER_LS041Y3		4
> +#define MIPID_VER_L4F00311		8
> +#define MIPID_VER_ACX565AKM		9
> +
> +struct acx565akm_panel {
> +	struct drm_panel panel;
> +
> +	struct spi_device *spi;
> +	struct gpio_desc *reset_gpio;
> +	struct backlight_device *backlight;
> +
> +	struct mutex mutex;
> +
> +	const char *name;
> +	u8 display_id[3];
> +	int model;
> +	int revision;
> +	bool has_bc;
> +	bool has_cabc;
> +
> +	bool enabled;
> +	unsigned int cabc_mode;
> +	/*
> +	 * Next value of jiffies when we can issue the next sleep in/out
> +	 * command.
> +	 */
> +	unsigned long hw_guard_end;
> +	unsigned long hw_guard_wait;		/* max guard time in jiffies */
> +};
> +
> +#define to_acx565akm_device(p) container_of(p, struct acx565akm_panel, panel)
> +
> +static void acx565akm_transfer(struct acx565akm_panel *lcd, int cmd,
> +			      const u8 *wbuf, int wlen, u8 *rbuf, int rlen)
> +{
> +	struct spi_message	m;
> +	struct spi_transfer	*x, xfer[5];
> +	int			ret;
> +
> +	spi_message_init(&m);
> +
> +	memset(xfer, 0, sizeof(xfer));
> +	x = &xfer[0];
> +
> +	cmd &=  0xff;
> +	x->tx_buf = &cmd;
> +	x->bits_per_word = 9;
> +	x->len = 2;
> +
> +	if (rlen > 1 && wlen == 0) {
> +		/*
> +		 * Between the command and the response data there is a
> +		 * dummy clock cycle. Add an extra bit after the command
> +		 * word to account for this.
> +		 */
> +		x->bits_per_word = 10;
> +		cmd <<= 1;
> +	}
> +	spi_message_add_tail(x, &m);
> +
> +	if (wlen) {
> +		x++;
> +		x->tx_buf = wbuf;
> +		x->len = wlen;
> +		x->bits_per_word = 9;
> +		spi_message_add_tail(x, &m);
> +	}
> +
> +	if (rlen) {
> +		x++;
> +		x->rx_buf	= rbuf;
> +		x->len		= rlen;
> +		spi_message_add_tail(x, &m);
> +	}
> +
> +	ret = spi_sync(lcd->spi, &m);
> +	if (ret < 0)
> +		dev_dbg(&lcd->spi->dev, "spi_sync %d\n", ret);
> +}
> +
> +static inline void acx565akm_cmd(struct acx565akm_panel *lcd, int cmd)
> +{
> +	acx565akm_transfer(lcd, cmd, NULL, 0, NULL, 0);
> +}
> +
> +static inline void acx565akm_write(struct acx565akm_panel *lcd,
> +			       int reg, const u8 *buf, int len)
> +{
> +	acx565akm_transfer(lcd, reg, buf, len, NULL, 0);
> +}
> +
> +static inline void acx565akm_read(struct acx565akm_panel *lcd,
> +			      int reg, u8 *buf, int len)
> +{
> +	acx565akm_transfer(lcd, reg, NULL, 0, buf, len);
> +}
> +
> +/* -----------------------------------------------------------------------------
> + * Auto Brightness Control Via sysfs
> + */
> +
> +static unsigned int acx565akm_get_cabc_mode(struct acx565akm_panel *lcd)
> +{
> +	return lcd->cabc_mode;
> +}
> +
> +static void acx565akm_set_cabc_mode(struct acx565akm_panel *lcd,
> +				    unsigned int mode)
> +{
> +	u16 cabc_ctrl;
> +
> +	lcd->cabc_mode = mode;
> +	if (!lcd->enabled)
> +		return;
> +	cabc_ctrl = 0;
> +	acx565akm_read(lcd, MIPID_CMD_READ_CABC, (u8 *)&cabc_ctrl, 1);
> +	cabc_ctrl &= ~3;
> +	cabc_ctrl |= (1 << 8) | (mode & 3);
> +	acx565akm_write(lcd, MIPID_CMD_WRITE_CABC, (u8 *)&cabc_ctrl, 2);
> +}
> +
> +static unsigned int acx565akm_get_hw_cabc_mode(struct acx565akm_panel *lcd)
> +{
> +	u8 cabc_ctrl;
> +
> +	acx565akm_read(lcd, MIPID_CMD_READ_CABC, &cabc_ctrl, 1);
> +	return cabc_ctrl & 3;
> +}
> +
> +static const char * const acx565akm_cabc_modes[] = {
> +	"off",		/* always used when CABC is not supported */
> +	"ui",
> +	"still-image",
> +	"moving-image",
> +};
> +
> +static ssize_t cabc_mode_show(struct device *dev,
> +			      struct device_attribute *attr,
> +			      char *buf)
> +{
> +	struct acx565akm_panel *lcd = dev_get_drvdata(dev);
> +	const char *mode_str;
> +	int mode;
> +
> +	if (!lcd->has_cabc)
> +		mode = 0;
> +	else
> +		mode = acx565akm_get_cabc_mode(lcd);
> +
> +	mode_str = "unknown";
> +	if (mode >= 0 && mode < ARRAY_SIZE(acx565akm_cabc_modes))
> +		mode_str = acx565akm_cabc_modes[mode];
> +
> +	return sprintf(buf, "%s\n", mode_str);
> +}
> +
> +static ssize_t cabc_mode_store(struct device *dev,
> +			       struct device_attribute *attr,
> +			       const char *buf, size_t count)
> +{
> +	struct acx565akm_panel *lcd = dev_get_drvdata(dev);
> +	unsigned int i;
> +
> +	for (i = 0; i < ARRAY_SIZE(acx565akm_cabc_modes); i++) {
> +		const char *mode_str = acx565akm_cabc_modes[i];
> +		int cmp_len = strlen(mode_str);
> +
> +		if (count > 0 && buf[count - 1] == '\n')
> +			count--;
> +		if (count != cmp_len)
> +			continue;
> +
> +		if (strncmp(buf, mode_str, cmp_len) == 0)
> +			break;
> +	}
> +
> +	if (i == ARRAY_SIZE(acx565akm_cabc_modes))
> +		return -EINVAL;
> +
> +	if (!lcd->has_cabc && i != 0)
> +		return -EINVAL;
> +
> +	mutex_lock(&lcd->mutex);
> +	acx565akm_set_cabc_mode(lcd, i);
> +	mutex_unlock(&lcd->mutex);
> +
> +	return count;
> +}
> +
> +static ssize_t cabc_available_modes_show(struct device *dev,
> +					 struct device_attribute *attr,
> +					 char *buf)
> +{
> +	struct acx565akm_panel *lcd = dev_get_drvdata(dev);
> +	unsigned int i;
> +	size_t len = 0;
> +
> +	if (!lcd->has_cabc)
> +		return sprintf(buf, "%s\n", acx565akm_cabc_modes[0]);
> +
> +	for (i = 0; i < ARRAY_SIZE(acx565akm_cabc_modes); i++)
> +		len += sprintf(&buf[len], "%s%s", i ? " " : "",
> +			       acx565akm_cabc_modes[i]);
> +
> +	buf[len++] = '\n';
> +
> +	return len;
> +}
> +
> +static DEVICE_ATTR_RW(cabc_mode);
> +static DEVICE_ATTR_RO(cabc_available_modes);
> +
> +static struct attribute *acx565akm_cabc_attrs[] = {
> +	&dev_attr_cabc_mode.attr,
> +	&dev_attr_cabc_available_modes.attr,
> +	NULL,
> +};
> +
> +static const struct attribute_group acx565akm_cabc_attr_group = {
> +	.attrs = acx565akm_cabc_attrs,
> +};
> +
> +/* -----------------------------------------------------------------------------
> + * Backlight Device
> + */
> +
> +static int acx565akm_get_actual_brightness(struct acx565akm_panel *lcd)
> +{
> +	u8 bv;
> +
> +	acx565akm_read(lcd, MIPI_DCS_GET_DISPLAY_BRIGHTNESS, &bv, 1);
> +
> +	return bv;
> +}
> +
> +static void acx565akm_set_brightness(struct acx565akm_panel *lcd, int level)
> +{
> +	u16 ctrl;
> +	int bv;
> +
> +	bv = level | (1 << 8);
> +	acx565akm_write(lcd, MIPI_DCS_SET_DISPLAY_BRIGHTNESS, (u8 *)&bv, 2);
> +
> +	acx565akm_read(lcd, MIPI_DCS_GET_CONTROL_DISPLAY, (u8 *)&ctrl, 1);
> +	if (level)
> +		ctrl |= CTRL_DISP_BRIGHTNESS_CTRL_ON |
> +			CTRL_DISP_BACKLIGHT_ON;
> +	else
> +		ctrl &= ~(CTRL_DISP_BRIGHTNESS_CTRL_ON |
> +			  CTRL_DISP_BACKLIGHT_ON);
> +
> +	ctrl |= 1 << 8;
> +	acx565akm_write(lcd, MIPI_DCS_WRITE_CONTROL_DISPLAY, (u8 *)&ctrl, 2);
> +}
> +
> +static int acx565akm_bl_update_status_locked(struct backlight_device *dev)
> +{
> +	struct acx565akm_panel *lcd = dev_get_drvdata(&dev->dev);
> +	int level;
> +
> +	if (dev->props.fb_blank == FB_BLANK_UNBLANK &&
> +	    dev->props.power == FB_BLANK_UNBLANK)
> +		level = dev->props.brightness;
> +	else
> +		level = 0;
> +
> +	acx565akm_set_brightness(lcd, level);
> +
> +	return 0;
> +}
> +
> +static int acx565akm_bl_update_status(struct backlight_device *dev)
> +{
> +	struct acx565akm_panel *lcd = dev_get_drvdata(&dev->dev);
> +	int ret;
> +
> +	mutex_lock(&lcd->mutex);
> +	ret = acx565akm_bl_update_status_locked(dev);
> +	mutex_unlock(&lcd->mutex);
> +
> +	return ret;
> +}
> +
> +static int acx565akm_bl_get_intensity(struct backlight_device *dev)
> +{
> +	struct acx565akm_panel *lcd = dev_get_drvdata(&dev->dev);
> +	unsigned int intensity;
> +
> +	mutex_lock(&lcd->mutex);
> +
> +	if (dev->props.fb_blank == FB_BLANK_UNBLANK &&
> +	    dev->props.power == FB_BLANK_UNBLANK)
> +		intensity = acx565akm_get_actual_brightness(lcd);
> +	else
> +		intensity = 0;
> +
> +	mutex_unlock(&lcd->mutex);
> +
> +	return intensity;
> +}
> +
> +static const struct backlight_ops acx565akm_bl_ops = {
> +	.get_brightness = acx565akm_bl_get_intensity,
> +	.update_status  = acx565akm_bl_update_status,
> +};
> +
> +static int acx565akm_backlight_init(struct acx565akm_panel *lcd)
> +{
> +	struct backlight_properties props = {
> +		.fb_blank = FB_BLANK_UNBLANK,
> +		.power = FB_BLANK_UNBLANK,
> +		.type = BACKLIGHT_RAW,
> +	};
> +	int ret;
> +
> +	lcd->backlight = backlight_device_register(lcd->name, &lcd->spi->dev,
> +						   lcd, &acx565akm_bl_ops,
> +						   &props);
> +	if (IS_ERR(lcd->backlight)) {
> +		ret = PTR_ERR(lcd->backlight);
> +		lcd->backlight = NULL;
> +		return ret;
> +	}
> +
> +	if (lcd->has_cabc) {
> +		ret = sysfs_create_group(&lcd->backlight->dev.kobj,
> +					 &acx565akm_cabc_attr_group);
> +		if (ret < 0) {
> +			dev_err(&lcd->spi->dev,
> +				"%s failed to create sysfs files\n", __func__);
> +			backlight_device_unregister(lcd->backlight);
> +			return ret;
> +		}
> +
> +		lcd->cabc_mode = acx565akm_get_hw_cabc_mode(lcd);
> +	}
> +
> +	lcd->backlight->props.max_brightness = 255;
> +	lcd->backlight->props.brightness = acx565akm_get_actual_brightness(lcd);
> +
> +	acx565akm_bl_update_status_locked(lcd->backlight);
> +
> +	return 0;
> +}
> +
> +static void acx565akm_backlight_cleanup(struct acx565akm_panel *lcd)
> +{
> +	if (lcd->has_cabc)
> +		sysfs_remove_group(&lcd->backlight->dev.kobj,
> +				   &acx565akm_cabc_attr_group);
> +
> +	backlight_device_unregister(lcd->backlight);
> +}
> +
> +/* -----------------------------------------------------------------------------
> + * DRM Bridge Operations
> + */
> +
> +static void acx565akm_set_sleep_mode(struct acx565akm_panel *lcd, int on)
> +{
> +	int cmd = on ? MIPI_DCS_ENTER_SLEEP_MODE : MIPI_DCS_EXIT_SLEEP_MODE;
> +	unsigned long wait;
> +
> +	/*
> +	 * We have to keep 120msec between sleep in/out commands.
> +	 * (8.2.15, 8.2.16).
> +	 */
> +	wait = lcd->hw_guard_end - jiffies;
> +	if ((long)wait > 0 && wait <= lcd->hw_guard_wait) {
> +		set_current_state(TASK_UNINTERRUPTIBLE);
> +		schedule_timeout(wait);
> +	}
> +
> +	acx565akm_cmd(lcd, cmd);
> +
> +	lcd->hw_guard_wait = msecs_to_jiffies(120);
> +	lcd->hw_guard_end = jiffies + lcd->hw_guard_wait;
> +}
> +
> +static void acx565akm_set_display_state(struct acx565akm_panel *lcd,
> +					int enabled)
> +{
> +	int cmd = enabled ? MIPI_DCS_SET_DISPLAY_ON : MIPI_DCS_SET_DISPLAY_OFF;
> +
> +	acx565akm_cmd(lcd, cmd);
> +}
> +
> +static int acx565akm_power_on(struct acx565akm_panel *lcd)
> +{
> +	/*FIXME tweak me */
> +	msleep(50);
> +
> +	gpiod_set_value(lcd->reset_gpio, 1);
> +
> +	if (lcd->enabled) {
> +		dev_dbg(&lcd->spi->dev, "panel already enabled\n");
> +		return 0;
> +	}
> +
> +	/*
> +	 * We have to meet all the following delay requirements:
> +	 * 1. tRW: reset pulse width 10usec (7.12.1)
> +	 * 2. tRT: reset cancel time 5msec (7.12.1)
> +	 * 3. Providing PCLK,HS,VS signals for 2 frames = ~50msec worst
> +	 *    case (7.6.2)
> +	 * 4. 120msec before the sleep out command (7.12.1)
> +	 */
> +	msleep(120);
> +
> +	acx565akm_set_sleep_mode(lcd, 0);
> +	lcd->enabled = true;
> +
> +	/* 5msec between sleep out and the next command. (8.2.16) */
> +	usleep_range(5000, 10000);
> +	acx565akm_set_display_state(lcd, 1);
> +	acx565akm_set_cabc_mode(lcd, lcd->cabc_mode);
> +
> +	return acx565akm_bl_update_status_locked(lcd->backlight);
> +}
> +
> +static void acx565akm_power_off(struct acx565akm_panel *lcd)
> +{
> +	if (!lcd->enabled)
> +		return;
> +
> +	acx565akm_set_display_state(lcd, 0);
> +	acx565akm_set_sleep_mode(lcd, 1);
> +	lcd->enabled = false;
> +	/*
> +	 * We have to provide PCLK,HS,VS signals for 2 frames (worst case
> +	 * ~50msec) after sending the sleep in command and asserting the
> +	 * reset signal. We probably could assert the reset w/o the delay
> +	 * but we still delay to avoid possible artifacts. (7.6.1)
> +	 */
> +	msleep(50);
> +
> +	gpiod_set_value(lcd->reset_gpio, 0);
> +
> +	/* FIXME need to tweak this delay */
> +	msleep(100);
> +}
> +
> +static int acx565akm_disable(struct drm_panel *panel)
> +{
> +	struct acx565akm_panel *lcd = to_acx565akm_device(panel);
> +
> +	mutex_lock(&lcd->mutex);
> +	acx565akm_power_off(lcd);
> +	mutex_unlock(&lcd->mutex);
> +
> +	return 0;
> +}
> +
> +static int acx565akm_enable(struct drm_panel *panel)
> +{
> +	struct acx565akm_panel *lcd = to_acx565akm_device(panel);
> +
> +	mutex_lock(&lcd->mutex);
> +	acx565akm_power_on(lcd);
> +	mutex_unlock(&lcd->mutex);
> +
> +	return 0;
> +}
> +
> +static const struct drm_display_mode acx565akm_mode = {
> +	.clock = 24000,
> +	.hdisplay = 800,
> +	.hsync_start = 800 + 28,
> +	.hsync_end = 800 + 28 + 4,
> +	.htotal = 800 + 28 + 4 + 24,
> +	.vdisplay = 480,
> +	.vsync_start = 480 + 3,
> +	.vsync_end = 480 + 3 + 3,
> +	.vtotal = 480 + 3 + 3 + 4,
> +	.vrefresh = 57,
> +	.type = DRM_MODE_TYPE_DRIVER | DRM_MODE_TYPE_PREFERRED,
> +	.flags = DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC,
> +	.width_mm = 77,
> +	.height_mm = 46,
> +};
> +
> +static int acx565akm_get_modes(struct drm_panel *panel)
> +{
> +	struct drm_connector *connector = panel->connector;
> +	struct drm_display_mode *mode;
> +
> +	mode = drm_mode_duplicate(panel->drm, &acx565akm_mode);
> +	if (!mode)
> +		return -ENOMEM;
> +
> +	drm_mode_set_name(mode);
> +	drm_mode_probed_add(connector, mode);
> +
> +	connector->display_info.width_mm = acx565akm_mode.width_mm;
> +	connector->display_info.height_mm = acx565akm_mode.height_mm;
> +	connector->display_info.bus_flags = DRM_BUS_FLAG_DE_HIGH
> +					  | DRM_BUS_FLAG_SYNC_SAMPLE_POSEDGE
> +					  | DRM_BUS_FLAG_PIXDATA_SAMPLE_NEGEDGE;
> +
> +	return 1;
> +}
> +
> +static const struct drm_panel_funcs acx565akm_funcs = {
> +	.disable = acx565akm_disable,
> +	.enable = acx565akm_enable,
> +	.get_modes = acx565akm_get_modes,
> +};
> +
> +/* -----------------------------------------------------------------------------
> + * Probe, Detect and Remove
> + */
> +
> +static int acx565akm_detect(struct acx565akm_panel *lcd)
> +{
> +	__be32 value;
> +	u32 status;
> +	int ret = 0;
> +
> +	/*
> +	 * After being taken out of reset the panel needs 5ms before the first
> +	 * command can be sent.
> +	 */
> +	gpiod_set_value(lcd->reset_gpio, 1);
> +	usleep_range(5000, 10000);
> +
> +	acx565akm_read(lcd, MIPI_DCS_GET_DISPLAY_STATUS, (u8 *)&value, 4);
> +	status = __be32_to_cpu(value);
> +	lcd->enabled = (status & (1 << 17)) && (status & (1 << 10));
> +
> +	dev_dbg(&lcd->spi->dev,
> +		"LCD panel %s by bootloader (status 0x%04x)\n",
> +		lcd->enabled ? "enabled" : "disabled ", status);
> +
> +	acx565akm_read(lcd, MIPI_DCS_GET_DISPLAY_ID, lcd->display_id, 3);
> +	dev_dbg(&lcd->spi->dev, "MIPI display ID: %02x%02x%02x\n",
> +		lcd->display_id[0], lcd->display_id[1], lcd->display_id[2]);
> +
> +	switch (lcd->display_id[0]) {
> +	case 0x10:
> +		lcd->model = MIPID_VER_ACX565AKM;
> +		lcd->name = "acx565akm";
> +		lcd->has_bc = 1;
> +		lcd->has_cabc = 1;
> +		break;
> +	case 0x29:
> +		lcd->model = MIPID_VER_L4F00311;
> +		lcd->name = "l4f00311";
> +		break;
> +	case 0x45:
> +		lcd->model = MIPID_VER_LPH8923;
> +		lcd->name = "lph8923";
> +		break;
> +	case 0x83:
> +		lcd->model = MIPID_VER_LS041Y3;
> +		lcd->name = "ls041y3";
> +		break;
> +	default:
> +		lcd->name = "unknown";
> +		dev_err(&lcd->spi->dev, "unknown display ID\n");
> +		ret = -ENODEV;
> +		goto done;
> +	}
> +
> +	lcd->revision = lcd->display_id[1];
> +
> +	dev_info(&lcd->spi->dev, "%s rev %02x panel detected\n",
> +		 lcd->name, lcd->revision);
> +
> +done:
> +	if (!lcd->enabled)
> +		gpiod_set_value(lcd->reset_gpio, 0);
> +
> +	return ret;
> +}
> +
> +static int acx565akm_probe(struct spi_device *spi)
> +{
> +	struct acx565akm_panel *lcd;
> +	int ret;
> +
> +	lcd = devm_kzalloc(&spi->dev, sizeof(*lcd), GFP_KERNEL);
> +	if (lcd == NULL)
> +		return -ENOMEM;
> +
> +	spi_set_drvdata(spi, lcd);
> +	spi->mode = SPI_MODE_3;
> +
> +	lcd->spi = spi;
> +	mutex_init(&lcd->mutex);
> +
> +	lcd->reset_gpio = devm_gpiod_get(&spi->dev, "reset", GPIOD_OUT_LOW);
> +	if (IS_ERR(lcd->reset_gpio)) {
> +		dev_err(&spi->dev, "failed to get reset GPIO\n");
> +		return PTR_ERR(lcd->reset_gpio);
> +	}
> +
> +	ret = acx565akm_detect(lcd);
> +	if (ret < 0) {
> +		dev_err(&spi->dev, "panel detection failed\n");
> +		return ret;
> +	}
> +
> +	if (lcd->has_bc) {
> +		ret = acx565akm_backlight_init(lcd);
> +		if (ret < 0)
> +			return ret;
> +	}
> +
> +	drm_panel_init(&lcd->panel);
> +	lcd->panel.dev = &lcd->spi->dev;
> +	lcd->panel.funcs = &acx565akm_funcs;
> +
> +	ret = drm_panel_add(&lcd->panel);
> +	if (ret < 0) {
> +		if (lcd->has_bc)
> +			acx565akm_backlight_cleanup(lcd);
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static int acx565akm_remove(struct spi_device *spi)
> +{
> +	struct acx565akm_panel *lcd = spi_get_drvdata(spi);
> +
> +	drm_panel_remove(&lcd->panel);
> +
> +	if (lcd->has_bc)
> +		acx565akm_backlight_cleanup(lcd);
> +
> +	drm_panel_disable(&lcd->panel);
> +	drm_panel_unprepare(&lcd->panel);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id acx565akm_of_match[] = {
> +	{ .compatible = "sony,acx565akm", },
> +	{ /* sentinel */ },
> +};
> +
> +MODULE_DEVICE_TABLE(of, acx565akm_of_match);
> +
> +static struct spi_driver acx565akm_driver = {
> +	.probe		= acx565akm_probe,
> +	.remove		= acx565akm_remove,
> +	.driver		= {
> +		.name	= "panel-sony-acx565akm",
> +		.of_match_table = acx565akm_of_match,
> +	},
> +};
> +
> +module_spi_driver(acx565akm_driver);
> +
> +MODULE_ALIAS("spi:sony,acx565akm");
> +MODULE_AUTHOR("Nokia Corporation");
> +MODULE_DESCRIPTION("Sony ACX565AKM LCD Panel Driver");
> +MODULE_LICENSE("GPL");
> -- 
> Regards,
> 
> Laurent Pinchart
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