Re: [PATCH 2/2] drm/panel: Add driver for Sony ACX424AKP panel

From: Thierry Reding <thierry.reding@gmail.com>
To: Linus Walleij <linus.walleij@linaro.org>
Cc: Sam Ravnborg <sam@ravnborg.org>, dri-devel@lists.freedesktop.org
Subject: Re: [PATCH 2/2] drm/panel: Add driver for Sony ACX424AKP panel
Date: Mon, 2 Sep 2019 12:32:19 +0200	[thread overview]
Message-ID: <20190902103219.GB12946@ulmo> (raw)
In-Reply-To: <20190902090633.24239-2-linus.walleij@linaro.org>

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On Mon, Sep 02, 2019 at 11:06:33AM +0200, Linus Walleij wrote:
> The Sony ACX424AKP is a command/videomode DSI panel for
> mobile devices. It is used on the ST-Ericsson HREF520
> reference design. We support video mode by default, but
> it is possible to switch the panel into command mode
> by using the bool property "dsi-command-mode".
> 
> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
> ---
>  drivers/gpu/drm/panel/Kconfig                |   7 +
>  drivers/gpu/drm/panel/Makefile               |   1 +
>  drivers/gpu/drm/panel/panel-sony-acx424akp.c | 530 +++++++++++++++++++
>  3 files changed, 538 insertions(+)
>  create mode 100644 drivers/gpu/drm/panel/panel-sony-acx424akp.c
> 
> diff --git a/drivers/gpu/drm/panel/Kconfig b/drivers/gpu/drm/panel/Kconfig
> index d9d931aa6e26..435388a874e2 100644
> --- a/drivers/gpu/drm/panel/Kconfig
> +++ b/drivers/gpu/drm/panel/Kconfig
> @@ -275,6 +275,13 @@ 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_ACX424AKP
> +	tristate "Sony ACX424AKP DSI command mode panel"
> +	depends on OF
> +	depends on DRM_MIPI_DSI
> +	depends on BACKLIGHT_CLASS_DEVICE
> +	select VIDEOMODE_HELPERS
> +
>  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 fb0cb3aaa9e6..9ed4d853267e 100644
> --- a/drivers/gpu/drm/panel/Makefile
> +++ b/drivers/gpu/drm/panel/Makefile
> @@ -28,5 +28,6 @@ obj-$(CONFIG_DRM_PANEL_SHARP_LQ101R1SX01) += panel-sharp-lq101r1sx01.o
>  obj-$(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-$(CONFIG_DRM_PANEL_SONY_ACX424AKP) += panel-sony-acx424akp.o
>  obj-$(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-acx424akp.c b/drivers/gpu/drm/panel/panel-sony-acx424akp.c
> new file mode 100644
> index 000000000000..807560d2a8ec
> --- /dev/null
> +++ b/drivers/gpu/drm/panel/panel-sony-acx424akp.c
> @@ -0,0 +1,530 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * MIPI-DSI Sony ACX424AKP panel driver. This is a 480x864
> + * AMOLED panel with a command-only DSI interface.
> + *
> + * Copyright (C) Linaro Ltd. 2019
> + * Author: Linus Walleij
> + * Based on code and know-how from Marcus Lorentzon
> + * Copyright (C) ST-Ericsson SA 2010
> + */
> +
> +#include <drm/drm_modes.h>
> +#include <drm/drm_mipi_dsi.h>
> +#include <drm/drm_panel.h>
> +#include <drm/drm_print.h>
> +#include <video/mipi_display.h>
> +
> +#include <linux/gpio/consumer.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/delay.h>
> +#include <linux/of.h>
> +#include <linux/module.h>
> +#include <linux/backlight.h>
> +
> +/* FIXME: move to <video/mipi_display.h> ? */
> +#define MIPI_DSI_DCS_SET_MDDI 0xAE
> +
> +#define DISPLAY_SONY_ACX424AKP_ID1	0x1b81
> +#define DISPLAY_SONY_ACX424AKP_ID2	0x1a81
> +#define DISPLAY_SONY_ACX424AKP_ID3	0x0080
> +
> +struct acx424akp {
> +	struct device *dev;
> +	struct drm_panel panel;
> +	struct backlight_device *bl;
> +	struct regulator *supply;
> +	struct gpio_desc *reset_gpio;
> +	u16 id;
> +	bool video_mode;
> +};
> +
> +static const struct drm_display_mode sony_acx424akp_vid_mode = {
> +	.clock = 330000,
> +	.hdisplay = 480,
> +	.hsync_start = 480 + 15,
> +	.hsync_end = 480 + 15 + 0,
> +	.htotal = 480 + 15 + 0 + 15,
> +	.vdisplay = 864,
> +	.vsync_start = 864 + 14,
> +	.vsync_end = 864 + 14 + 1,
> +	.vtotal = 864 + 14 + 1 + 11,
> +	.vrefresh = 60,
> +	.width_mm = 48,
> +	.height_mm = 84,
> +	.flags = DRM_MODE_FLAG_PVSYNC,
> +};
> +
> +/*
> + * The timings are not very helpful as the display is used in
> + * command mode.
> + */
> +static const struct drm_display_mode sony_acx424akp_cmd_mode = {
> +	/* HS clock, (htotal*vtotal*vrefresh)/1000 */
> +	.clock = 420160,
> +	.hdisplay = 480,
> +	.hsync_start = 480 + 154,
> +	.hsync_end = 480 + 154 + 16,
> +	.htotal = 480 + 154 + 16 + 32,
> +	.vdisplay = 864,
> +	.vsync_start = 864 + 1,
> +	.vsync_end = 864 + 1 + 1,
> +	.vtotal = 864 + 1 + 1 + 1,
> +	/*
> +	 * This depends on the clocking HS vs LP rate, this value
> +	 * is calculated as:
> +	 * vrefresh = (clock * 1000) / (htotal*vtotal)
> +	 */
> +	.vrefresh = 816,

That's a bit odd. My understanding is that command mode can be done in
continuous mode or in non-continuous mode. In continuous mode you would
typically achieve a similar refresh rate as in video mode. For non-
continuous mode you basically have a variable refresh rate.

For continuous mode you probably want 60 Hz here and for VRR there's
probably no sensible value to set this to. In the latter case, I don't
think it makes sense to set anything arbitrary like you have above.
Perhaps better to just set it to 0 as a way of signalling that this is
actually dependent on when the display hardware sends a new frame?

Have you actually run this is command mode? If so, what's the actual
refresh rate? Do you do on-demand updates or do you run in continuous
mode?

> +	.width_mm = 48,
> +	.height_mm = 84,
> +};
> +
> +static inline struct acx424akp *panel_to_acx424akp(struct drm_panel *panel)
> +{
> +	return container_of(panel, struct acx424akp, panel);
> +}
> +
> +#define FOSC			20 /* 20Mhz */
> +#define SCALE_FACTOR_NS_DIV_MHZ	1000
> +
> +static int acx424akp_set_brightness(struct backlight_device *bl)
> +{
> +	struct acx424akp *acx = bl_get_data(bl);
> +	struct mipi_dsi_device *dsi = to_mipi_dsi_device(acx->dev);
> +	int period_ns = 1023;
> +	int duty_ns = bl->props.brightness;
> +	u8 pwm_ratio;
> +	u8 pwm_div;
> +	u8 par;
> +	int ret;
> +
> +	/* Calculate the PWM duty cycle in n/256's */
> +	pwm_ratio = max(((duty_ns * 256) / period_ns) - 1, 1);
> +	pwm_div = max(1,
> +		      ((FOSC * period_ns) / 256) /
> +		      SCALE_FACTOR_NS_DIV_MHZ);
> +
> +	/* Set up PWM dutycycle ONE byte (differs from the standard) */
> +	DRM_DEV_DEBUG(acx->dev, "calculated duty cycle %02x\n", pwm_ratio);
> +	ret = mipi_dsi_dcs_write(dsi, MIPI_DCS_SET_DISPLAY_BRIGHTNESS,
> +				 &pwm_ratio, 1);
> +	if (ret < 0) {
> +		DRM_DEV_ERROR(acx->dev,
> +			      "failed to set display PWM ratio (%d)\n",
> +			      ret);
> +		return ret;
> +	}
> +
> +	/*
> +	 * Sequence to write PWMDIV:
> +	 *	address		data
> +	 *	0xF3		0xAA   CMD2 Unlock
> +	 *	0x00		0x01   Enter CMD2 page 0
> +	 *	0X7D		0x01   No reload MTP of CMD2 P1
> +	 *	0x22		PWMDIV
> +	 *	0x7F		0xAA   CMD2 page 1 lock
> +	 */
> +	par = 0xaa;
> +	ret = mipi_dsi_dcs_write(dsi, 0xf3, &par, 1);
> +	if (ret < 0) {
> +		DRM_DEV_ERROR(acx->dev,
> +			      "failed to unlock CMD 2 (%d)\n",
> +			      ret);
> +		return ret;
> +	}
> +	par = 0x01;
> +	ret = mipi_dsi_dcs_write(dsi, 0x00, &par, 1);
> +	if (ret < 0) {
> +		DRM_DEV_ERROR(acx->dev,
> +			      "failed to enter page 1 (%d)\n",
> +			      ret);
> +		return ret;
> +	}
> +	par = 0x01;
> +	ret = mipi_dsi_dcs_write(dsi, 0x7d, &par, 1);
> +	if (ret < 0) {
> +		DRM_DEV_ERROR(acx->dev,
> +			      "failed to disable MTP reload (%d)\n",
> +			      ret);
> +		return ret;
> +	}
> +	ret = mipi_dsi_dcs_write(dsi, 0x22, &pwm_div, 1);
> +	if (ret < 0) {
> +		DRM_DEV_ERROR(acx->dev,
> +			      "failed to set PWM divisor (%d)\n",
> +			      ret);
> +		return ret;
> +	}
> +	par = 0xaa;
> +	ret = mipi_dsi_dcs_write(dsi, 0x7f, &par, 1);
> +	if (ret < 0) {
> +		DRM_DEV_ERROR(acx->dev,
> +			      "failed to lock CMD 2 (%d)\n",
> +			      ret);
> +		return ret;
> +	}
> +
> +	/* Enable backlight */
> +	par = 0x24;
> +	ret = mipi_dsi_dcs_write(dsi, MIPI_DCS_WRITE_CONTROL_DISPLAY,
> +				 &par, 1);
> +	if (ret < 0) {
> +		DRM_DEV_ERROR(acx->dev,
> +			      "failed to enable display backlight (%d)\n",
> +			      ret);
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static const struct backlight_ops acx424akp_bl_ops = {
> +	.update_status = acx424akp_set_brightness,
> +};
> +
> +static int acx424akp_read_id(struct acx424akp *acx)
> +{
> +	struct mipi_dsi_device *dsi = to_mipi_dsi_device(acx->dev);
> +	u8 id1, id2, id3;
> +	u16 val;
> +	size_t len;
> +	int ret;
> +
> +	len = 1;
> +
> +	ret = mipi_dsi_dcs_read(dsi, 0xda, &id1, len);
> +	if (ret < 0) {
> +		DRM_DEV_ERROR(acx->dev, "could not read device ID byte 1\n");
> +		return ret;
> +	}
> +	ret = mipi_dsi_dcs_read(dsi, 0xdb, &id2, len);
> +	if (ret < 0) {
> +		DRM_DEV_ERROR(acx->dev, "could not read device ID byte 2\n");
> +		return ret;
> +	}
> +	ret = mipi_dsi_dcs_read(dsi, 0xdc, &id3, len);
> +	if (ret < 0) {
> +		DRM_DEV_ERROR(acx->dev, "could not read device ID byte 3\n");
> +		return ret;
> +	}
> +
> +	val = (id3 << 8) | id2;

Don't you want to OR in id1 here as well? Seems a bit odd to read it but
then not use it.

> +
> +	switch (val) {
> +	case DISPLAY_SONY_ACX424AKP_ID1:
> +	case DISPLAY_SONY_ACX424AKP_ID2:
> +	case DISPLAY_SONY_ACX424AKP_ID3:
> +		DRM_DEV_INFO(acx->dev, "panel ID: %04x\n", val);
> +		break;
> +	default:
> +		DRM_DEV_ERROR(acx->dev, "unknown panel ID: %04x\n", val);
> +		break;
> +	};
> +	acx->id = val;
> +
> +	return 0;
> +}
> +
> +static int acx424akp_power_on(struct acx424akp *acx)
> +{
> +	int ret;
> +
> +	ret = regulator_enable(acx->supply);
> +	if (ret) {
> +		DRM_DEV_ERROR(acx->dev, "failed to enable supply (%d)\n", ret);
> +		return ret;
> +	}
> +
> +	/* Assert RESET */
> +	gpiod_set_value_cansleep(acx->reset_gpio, 1);
> +	udelay(20);
> +	/* De-assert RESET */
> +	gpiod_set_value_cansleep(acx->reset_gpio, 0);
> +	msleep(11);
> +
> +	return 0;
> +}
> +
> +static int acx424akp_prepare(struct drm_panel *panel)
> +{
> +	struct acx424akp *acx = panel_to_acx424akp(panel);
> +	struct mipi_dsi_device *dsi = to_mipi_dsi_device(acx->dev);
> +	const u8 mddi = 3;
> +	int ret;
> +
> +	ret = acx424akp_power_on(acx);
> +	if (ret)
> +		return ret;
> +
> +	/* Enabe tearing mode: send TE (tearing effect) at VBLANK */
> +	ret = mipi_dsi_dcs_set_tear_on(dsi,
> +				       MIPI_DSI_DCS_TEAR_MODE_VBLANK);
> +	if (ret) {
> +		DRM_DEV_ERROR(acx->dev, "failed to enable vblank TE (%d)\n",
> +			      ret);
> +		return ret;
> +	}
> +
> +	/* Set MDDI - doesn't seem to work? */
> +	ret = mipi_dsi_dcs_write(dsi, MIPI_DSI_DCS_SET_MDDI,
> +				 &mddi, sizeof(mddi));
> +	if (ret < 0) {
> +		DRM_DEV_ERROR(acx->dev, "failed to set MDDI (%d)\n", ret);
> +		return ret;
> +	}
> +
> +	acx->bl->props.power = FB_BLANK_NORMAL;
> +
> +	return 0;
> +}
> +
> +static void acx424akp_power_off(struct acx424akp *acx)
> +{
> +	/* Assert RESET */
> +	gpiod_set_value_cansleep(acx->reset_gpio, 1);
> +	msleep(11);
> +
> +	regulator_disable(acx->supply);
> +}
> +
> +static int acx424akp_unprepare(struct drm_panel *panel)
> +{
> +	struct acx424akp *acx = panel_to_acx424akp(panel);
> +
> +	acx424akp_power_off(acx);
> +	acx->bl->props.power = FB_BLANK_POWERDOWN;
> +
> +	return 0;
> +}
> +
> +static int acx424akp_enable(struct drm_panel *panel)
> +{
> +	struct acx424akp *acx = panel_to_acx424akp(panel);
> +	struct mipi_dsi_device *dsi = to_mipi_dsi_device(acx->dev);
> +	int ret;
> +
> +	/* Exit sleep mode */
> +	ret = mipi_dsi_dcs_exit_sleep_mode(dsi);
> +	if (ret) {
> +		DRM_DEV_ERROR(acx->dev, "failed to exit sleep mode (%d)\n",
> +			      ret);
> +		return ret;
> +	}
> +	msleep(140);
> +
> +	ret = mipi_dsi_dcs_set_display_on(dsi);
> +	if (ret) {
> +		DRM_DEV_ERROR(acx->dev, "failed to turn display on (%d)\n",
> +			      ret);
> +		return ret;
> +	}
> +	if (acx->video_mode) {
> +		/* In video mode turn peripheral on */
> +		ret = mipi_dsi_turn_on_peripheral(dsi);
> +		if (ret) {
> +			dev_err(acx->dev, "failed to turn on peripheral\n");
> +			return ret;
> +		}
> +	}
> +
> +	acx->bl->props.power = FB_BLANK_UNBLANK;
> +
> +	return 0;
> +}
> +
> +static int acx424akp_disable(struct drm_panel *panel)
> +{
> +	struct acx424akp *acx = panel_to_acx424akp(panel);
> +	struct mipi_dsi_device *dsi = to_mipi_dsi_device(acx->dev);
> +	u8 par;
> +	int ret;
> +
> +	/* Disable backlight */
> +	par = 0x00;
> +	ret = mipi_dsi_dcs_write(dsi, MIPI_DCS_WRITE_CONTROL_DISPLAY,
> +				 &par, 1);
> +	if (ret) {
> +		DRM_DEV_ERROR(acx->dev,
> +			      "failed to disable display backlight (%d)\n",
> +			      ret);
> +		return ret;
> +	}
> +
> +	ret = mipi_dsi_dcs_set_display_off(dsi);
> +	if (ret) {
> +		DRM_DEV_ERROR(acx->dev, "failed to turn display off (%d)\n",
> +			      ret);
> +		return ret;
> +	}
> +
> +	/* Enter sleep mode */
> +	ret = mipi_dsi_dcs_enter_sleep_mode(dsi);
> +	if (ret) {
> +		DRM_DEV_ERROR(acx->dev, "failed to enter sleep mode (%d)\n",
> +			      ret);
> +		return ret;
> +	}
> +	msleep(85);
> +
> +	acx->bl->props.power = FB_BLANK_NORMAL;
> +
> +	return 0;
> +}
> +
> +static int acx424akp_get_modes(struct drm_panel *panel)
> +{
> +	struct acx424akp *acx = panel_to_acx424akp(panel);
> +	struct drm_connector *connector = panel->connector;
> +	struct drm_display_mode *mode;
> +
> +	if (acx->video_mode)
> +		mode = drm_mode_duplicate(panel->drm,
> +					  &sony_acx424akp_vid_mode);
> +	else
> +		mode = drm_mode_duplicate(panel->drm,
> +					  &sony_acx424akp_cmd_mode);
> +	if (!mode) {
> +		DRM_ERROR("bad mode or failed to add mode\n");
> +		return -EINVAL;
> +	}
> +	drm_mode_set_name(mode);
> +	mode->type = DRM_MODE_TYPE_DRIVER | DRM_MODE_TYPE_PREFERRED;
> +
> +	connector->display_info.width_mm = mode->width_mm;
> +	connector->display_info.height_mm = mode->height_mm;
> +
> +	drm_mode_probed_add(connector, mode);
> +
> +	return 1; /* Number of modes */
> +}
> +
> +static const struct drm_panel_funcs acx424akp_drm_funcs = {
> +	.disable = acx424akp_disable,
> +	.unprepare = acx424akp_unprepare,
> +	.prepare = acx424akp_prepare,
> +	.enable = acx424akp_enable,
> +	.get_modes = acx424akp_get_modes,
> +};
> +
> +static int acx424akp_probe(struct mipi_dsi_device *dsi)
> +{
> +	struct device *dev = &dsi->dev;
> +	struct acx424akp *acx;
> +	int ret;
> +	int i;

unsigned int?

> +
> +	acx = devm_kzalloc(dev, sizeof(struct acx424akp), GFP_KERNEL);
> +	if (!acx)
> +		return -ENOMEM;
> +	acx->video_mode = !of_property_read_bool(dev->of_node,
> +						 "dsi-command-mode");
> +
> +	mipi_dsi_set_drvdata(dsi, acx);
> +	acx->dev = dev;
> +
> +	dsi->lanes = 2;
> +	dsi->format = MIPI_DSI_FMT_RGB888;
> +	dsi->hs_rate = 420160000;
> +	dsi->lp_rate = 19200000;
> +
> +	if (acx->video_mode)
> +		dsi->mode_flags =
> +			MIPI_DSI_MODE_VIDEO |
> +			MIPI_DSI_MODE_VIDEO_BURST |
> +			MIPI_DSI_MODE_VIDEO_SYNC_PULSE;
> +	else
> +		dsi->mode_flags =
> +			MIPI_DSI_CLOCK_NON_CONTINUOUS |
> +			MIPI_DSI_MODE_EOT_PACKET;
> +
> +

Gratuituous blank line.

> +	acx->supply = devm_regulator_get(dev, "vddi");
> +	if (IS_ERR(acx->supply))
> +		return PTR_ERR(acx->supply);
> +
> +	/* This asserts RESET by default */
> +	acx->reset_gpio = devm_gpiod_get_optional(dev, "reset",
> +						 GPIOD_OUT_HIGH);
> +	if (IS_ERR(acx->reset_gpio)) {
> +		ret = PTR_ERR(acx->reset_gpio);
> +		if (ret != -EPROBE_DEFER)
> +			DRM_DEV_ERROR(dev, "failed to request GPIO (%d)\n",
> +				      ret);
> +		return ret;
> +	}
> +
> +	drm_panel_init(&acx->panel);
> +	acx->panel.dev = dev;
> +	acx->panel.funcs = &acx424akp_drm_funcs;
> +
> +	acx->bl = devm_backlight_device_register(dev, "acx424akp", dev, acx,
> +						 &acx424akp_bl_ops, NULL);
> +	if (IS_ERR(acx->bl)) {
> +		DRM_DEV_ERROR(dev, "failed to register backlight device\n");
> +		return PTR_ERR(acx->bl);
> +	}
> +	acx->bl->props.max_brightness = 1023;
> +	acx->bl->props.brightness = 512;
> +	acx->bl->props.power = FB_BLANK_POWERDOWN;
> +
> +	ret = drm_panel_add(&acx->panel);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = acx424akp_power_on(acx);
> +	if (ret) {
> +		DRM_DEV_ERROR(dev, "failed to power up display\n");
> +		return ret;
> +	}
> +
> +	/* Read device ID */
> +	i = 0;
> +	do {
> +		ret = acx424akp_read_id(acx);
> +		if (ret)
> +			continue;
> +	} while (ret && i++ < 5);

Seems rather redundant to have both an "if (ret) continue;" and the ret
check in the while's condition. A more idiomatic way to write this would
be:

	for (i = 0; i < 5; i++) {
		ret = acx424akp_read_id(acx);
		if (!ret)
			break;
	}

Thierry

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