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Date:   Sat, 23 Feb 2019 23:03:04 +0100
From:   Sam Ravnborg <sam@ravnborg.org>
To:     Guido =?iso-8859-1?Q?G=FCnther?= <agx@sigxcpu.org>
Cc:     Thierry Reding <thierry.reding@gmail.com>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>, linux-kernel@vger.kernel.org,
        dri-devel@lists.freedesktop.org
Subject: Re: [PATCH 3/3] drm/panel: Add Rocktech jh057n00900 panel driver
Message-ID: <20190223220304.GA20290@ravnborg.org>
References: <cover.1550943220.git.agx@sigxcpu.org>
 <79858664af8ee2f725e53d902ce46b447ac8fcfc.1550943220.git.agx@sigxcpu.org>
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Hi Guido.

Thanks for this patch.
See below for some review feedback.

The driver includes the "allpixelson_set" debugfs feature.
Is this a debug leftover, or is there a real need for this?
If this is a debug feature that is no logner needed then no
need to add it to the mainline driver.

	Sam

On Sat, Feb 23, 2019 at 06:39:44PM +0100, Guido G?nther wrote:
> Support Rocktech jh057n00900 5.5" 720x1440 TFT LCD panel. It is a MIPI
> DSI video mode panel.
> 
> The panel seems to use a Sitronix ST7703 look alike (most of the
> commands look similar to the ST7703's data sheet but use a different
> number of parameters). The initial version of the DSI init sequence
> (including sleeps) were provided by the vendor. Sleeps were reduced
> considerably though to speed up initialization.
> 
> Signed-off-by: Guido G?nther <agx@sigxcpu.org>
> ---
> +++ b/drivers/gpu/drm/panel/panel-rocktech-jh057n00900.c
> @@ -0,0 +1,414 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Rockteck jh057n00900 5.5" MIPI-DSI panel driver
> + *
> + * Copyright (C) Purism SPC 2019
> + */
> +#include <drm/drmP.h>
> +#include <drm/drm_mipi_dsi.h>
> +#include <drm/drm_panel.h>
> +#include <linux/backlight.h>
> +#include <linux/gpio/consumer.h>
> +#include <video/mipi_display.h>
> +#include <video/display_timing.h>
> +#include <linux/debugfs.h>
1) Drop use of drmP.h - it is dreprecated and shall not be used for new drivers
2) Group the include files, and within each group sort them alphabetically

> +
> +#define DRV_NAME "jh057n00900"
> +
> +/* Manufacturer specific Commands send via DSI */
> +#define ST7703_CMD_ALL_PIXEL_OFF 0x22
> +#define ST7703_CMD_ALL_PIXEL_ON	 0x23
> +#define ST7703_CMD_SETDISP	 0xB2
> +#define ST7703_CMD_SETRGBIF	 0xB3
> +#define ST7703_CMD_SETCYC	 0xB4
> +#define ST7703_CMD_SETBGP	 0xB5
> +#define ST7703_CMD_SETVCOM	 0xB6
> +#define ST7703_CMD_SETOTP	 0xB7
> +#define ST7703_CMD_SETPOWER_EXT	 0xB8
> +#define ST7703_CMD_SETEXTC	 0xB9
> +#define ST7703_CMD_SETMIPI	 0xBA
> +#define ST7703_CMD_SETVDC	 0xBC
> +#define ST7703_CMD_SETSCR	 0xC0
> +#define ST7703_CMD_SETPOWER	 0xC1
> +#define ST7703_CMD_SETPANEL	 0xCC
> +#define ST7703_CMD_SETGAMMA	 0xE0
> +#define ST7703_CMD_SETEQ	 0xE3
> +#define ST7703_CMD_SETGIP1	 0xE9
> +#define ST7703_CMD_SETGIP2	 0xEA
> +
> +struct jh057n {
> +	struct device *dev;
> +	struct drm_panel panel;
> +	struct gpio_desc *reset_gpio;
> +	struct backlight_device *backlight;
> +	bool prepared;
> +	bool enabled;
enabled is used only to protect from calling backlight_disable()
again. There is nothing (as far as I can see) that should make
calling backlight_disbale() bad if already disabled.
So consider if this can be dropped.


> +
> +	struct dentry *debugfs;
> +};
> +
> +static inline struct jh057n *panel_to_jh057n(struct drm_panel *panel)
> +{
> +	return container_of(panel, struct jh057n, panel);
> +}
> +
> +#define dsi_generic_write_seq(dsi, seq...) do {				\
> +		static const u8 d[] = { seq };				\
> +		int ret;						\
> +		ret = mipi_dsi_generic_write(dsi, d, ARRAY_SIZE(d));	\
> +		if (ret < 0)						\
> +			return ret;					\
> +	} while (0)
> +
> +static int jh057n_init_sequence(struct jh057n *ctx)
> +{
> +	struct mipi_dsi_device *dsi = to_mipi_dsi_device(ctx->dev);
> +	struct device *dev = ctx->dev;
> +	int ret;
> +
> +	/*
> +	 * Init sequence was supplied by the panel vendor. Most of the commands
> +	 * resemble the ST7703 but the number of parameters often don't match
> +	 * so it's likely a clone.
> +	 */
> +	dsi_generic_write_seq(dsi, ST7703_CMD_SETEXTC,
> +			      0xF1, 0x12, 0x83);
> +	dsi_generic_write_seq(dsi, ST7703_CMD_SETRGBIF,
> +			      0x10, 0x10, 0x05, 0x05, 0x03, 0xFF, 0x00, 0x00,
> +			      0x00, 0x00);
> +	dsi_generic_write_seq(dsi, ST7703_CMD_SETSCR,
> +			      0x73, 0x73, 0x50, 0x50, 0x00, 0x00, 0x08, 0x70,
> +			      0x00);
> +	dsi_generic_write_seq(dsi, ST7703_CMD_SETVDC, 0x4E);
> +	dsi_generic_write_seq(dsi, ST7703_CMD_SETPANEL, 0x0B);
> +	dsi_generic_write_seq(dsi, ST7703_CMD_SETCYC, 0x80);
> +	dsi_generic_write_seq(dsi, ST7703_CMD_SETDISP, 0xF0, 0x12, 0x30);
> +	dsi_generic_write_seq(dsi, ST7703_CMD_SETEQ,
> +			      0x07, 0x07, 0x0B, 0x0B, 0x03, 0x0B, 0x00, 0x00,
> +			      0x00, 0x00, 0xFF, 0x00, 0xC0, 0x10);
> +	dsi_generic_write_seq(dsi, ST7703_CMD_SETBGP, 0x08, 0x08);
> +	msleep(20);
> +
> +	dsi_generic_write_seq(dsi, ST7703_CMD_SETVCOM, 0x3F, 0x3F);
> +	dsi_generic_write_seq(dsi, 0xBF, 0x02, 0x11, 0x00);
> +	dsi_generic_write_seq(dsi, ST7703_CMD_SETGIP1,
> +			      0x82, 0x10, 0x06, 0x05, 0x9E, 0x0A, 0xA5, 0x12,
> +			      0x31, 0x23, 0x37, 0x83, 0x04, 0xBC, 0x27, 0x38,
> +			      0x0C, 0x00, 0x03, 0x00, 0x00, 0x00, 0x0C, 0x00,
> +			      0x03, 0x00, 0x00, 0x00, 0x75, 0x75, 0x31, 0x88,
> +			      0x88, 0x88, 0x88, 0x88, 0x88, 0x13, 0x88, 0x64,
> +			      0x64, 0x20, 0x88, 0x88, 0x88, 0x88, 0x88, 0x88,
> +			      0x02, 0x88, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
> +			      0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00);
> +	dsi_generic_write_seq(dsi, ST7703_CMD_SETGIP2,
> +			      0x02, 0x21, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
> +			      0x00, 0x00, 0x00, 0x00, 0x02, 0x46, 0x02, 0x88,
> +			      0x88, 0x88, 0x88, 0x88, 0x88, 0x64, 0x88, 0x13,
> +			      0x57, 0x13, 0x88, 0x88, 0x88, 0x88, 0x88, 0x88,
> +			      0x75, 0x88, 0x23, 0x14, 0x00, 0x00, 0x02, 0x00,
> +			      0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
> +			      0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x30, 0x0A,
> +			      0xA5, 0x00, 0x00, 0x00, 0x00);
> +	dsi_generic_write_seq(dsi, ST7703_CMD_SETGAMMA,
> +			      0x00, 0x09, 0x0E, 0x29, 0x2D, 0x3C, 0x41, 0x37,
> +			      0x07, 0x0B, 0x0D, 0x10, 0x11, 0x0F, 0x10, 0x11,
> +			      0x18, 0x00, 0x09, 0x0E, 0x29, 0x2D, 0x3C, 0x41,
> +			      0x37, 0x07, 0x0B, 0x0D, 0x10, 0x11, 0x0F, 0x10,
> +			      0x11, 0x18);
> +	msleep(20);
> +
> +	ret = mipi_dsi_dcs_exit_sleep_mode(dsi);
> +	if (ret < 0) {
> +		DRM_DEV_ERROR(dev, "Failed to exit sleep mode");
> +		return ret;
> +	}
> +	/* Panel is operational 120 msec after reset */
> +	msleep(60);
> +	ret = mipi_dsi_dcs_set_display_on(dsi);
> +	if (ret)
> +		return ret;
> +
> +	DRM_DEV_DEBUG_DRIVER(dev, "Panel init sequence done");
> +	return 0;
> +}
> +
> +static int jh057n_disable(struct drm_panel *panel)
> +{
> +	struct jh057n *ctx = panel_to_jh057n(panel);
> +	int ret;
> +
> +	if (!ctx->enabled)
> +		return 0;
> +
> +	ret = backlight_disable(ctx->backlight);
> +	if (ret < 0)
> +		return ret;
> +
> +	ctx->enabled = false;
> +
> +	return 0;
> +}

If ctx->enable is dropped then this function becomes:

> +static int jh057n_disable(struct drm_panel *panel)
> +{
> +	struct jh057n *ctx = panel_to_jh057n(panel);
> +
> +	backlight_disable(ctx->backlight);
> +
> +	return 0;
> +}


> +static const struct drm_display_mode default_mode = {
> +	.hdisplay    = 720,
> +	.hsync_start = 720 + 90,
> +	.hsync_end   = 720 + 90 + 20,
> +	.htotal	     = 720 + 90 + 20 + 20,
> +	.vdisplay    = 1440,
> +	.vsync_start = 1440 + 20,
> +	.vsync_end   = 1440 + 20 + 4,
> +	.vtotal	     = 1440 + 20 + 4 + 12,
> +	.vrefresh    = 60,
> +	.clock	     = 75276,
> +	.flags	     = DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC,
> +	.width_mm    = 65,
> +	.height_mm   = 130,
> +};
> +
> +static int jh057n_get_modes(struct drm_panel *panel)
> +{
> +	struct drm_display_mode *mode;
> +	u32 bus_format = MEDIA_BUS_FMT_RGB888_1X24;
> +	int ret;
> +
> +	mode = drm_mode_duplicate(panel->drm, &default_mode);
> +	if (!mode) {
> +		DRM_ERROR("Failed to add mode %ux%ux@%u",
Should this be?
> +		DRM_ERROR("Failed to add mode %ux%u@%u",
(Note the second 'x' was dropped.


> +			  default_mode.hdisplay, default_mode.vdisplay,
> +			  default_mode.vrefresh);
> +		return -ENOMEM;
> +	}
> +
> +	drm_mode_set_name(mode);
> +
> +	mode->type = DRM_MODE_TYPE_DRIVER | DRM_MODE_TYPE_PREFERRED;
> +	panel->connector->display_info.width_mm = mode->width_mm;
> +	panel->connector->display_info.height_mm = mode->height_mm;
> +	ret = drm_display_info_set_bus_formats(&panel->connector->display_info,
> +					       &bus_format, 1);
It is my understanding that for spi controlled displays there is no need to set
the bus_format.

> +	if (ret)
> +		return ret;
> +
> +	drm_mode_probed_add(panel->connector, mode);
> +
> +	return 1;
> +}
> +

> +static int allpixelson_set(void *data, u64 val)
> +{
> +	struct jh057n *ctx = data;
> +	struct mipi_dsi_device *dsi = to_mipi_dsi_device(ctx->dev);
> +
> +	DRM_DEV_DEBUG_DRIVER(ctx->dev, "Setting all pixels on");
> +	dsi_generic_write_seq(dsi, ST7703_CMD_ALL_PIXEL_ON);
> +	msleep(val*1000);
If this is kept, then add spaces around operator '*'
> +	/* Reset the panel to get video back */
> +	drm_panel_disable(&ctx->panel);
> +	drm_panel_unprepare(&ctx->panel);
> +	drm_panel_prepare(&ctx->panel);
> +	drm_panel_enable(&ctx->panel);
> +
> +	return 0;
> +}
> +
> +DEFINE_SIMPLE_ATTRIBUTE(allpixelson_fops, NULL,
> +			allpixelson_set, "%llu\n");
> +
> +static int jh057n_debugfs_init(struct jh057n *ctx)
> +{
> +	struct dentry *f;
> +
> +	ctx->debugfs = debugfs_create_dir(DRV_NAME, NULL);
> +	if (!ctx->debugfs)
> +		return -ENOMEM;
> +
> +	f = debugfs_create_file("allpixelson", 0600,
> +				ctx->debugfs, ctx, &allpixelson_fops);
> +	if (!f)
> +		return -ENOMEM;
> +
> +	return 0;
> +}
> +
> +static void jh057n_debugfs_remove(struct jh057n *ctx)
> +{
> +	debugfs_remove_recursive(ctx->debugfs);
> +	ctx->debugfs = NULL;
> +}
> +
> +static int jh057n_probe(struct mipi_dsi_device *dsi)
> +{
> +	struct device *dev = &dsi->dev;
> +	struct jh057n *ctx;
> +	int ret;
> +
> +	ctx = devm_kzalloc(dev, sizeof(*ctx), GFP_KERNEL);
> +	if (!ctx)
> +		return -ENOMEM;
> +
> +	ctx->reset_gpio = devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW);
> +	if (IS_ERR(ctx->reset_gpio)) {
> +		DRM_DEV_ERROR(dev, "cannot get reset gpio");
> +		return PTR_ERR(ctx->reset_gpio);
> +	}
> +
> +	mipi_dsi_set_drvdata(dsi, ctx);
> +
> +	ctx->dev = dev;
> +
> +	dsi->lanes = 4;
> +	dsi->format = MIPI_DSI_FMT_RGB888;
> +	dsi->mode_flags = MIPI_DSI_MODE_VIDEO |
> +		MIPI_DSI_MODE_VIDEO_BURST | MIPI_DSI_MODE_VIDEO_SYNC_PULSE;
> +
> +	ctx->backlight = devm_of_find_backlight(dev);
> +	if (IS_ERR(ctx->backlight))
> +		return PTR_ERR(ctx->backlight);
> +
> +	drm_panel_init(&ctx->panel);
> +	ctx->panel.dev = dev;
> +	ctx->panel.funcs = &jh057n_drm_funcs;
> +
> +	drm_panel_add(&ctx->panel);
> +
> +	ret = mipi_dsi_attach(dsi);
> +	if (ret < 0) {
> +		DRM_DEV_ERROR(dev, "mipi_dsi_attach failed. Is host ready?");
> +		drm_panel_remove(&ctx->panel);
> +		goto err;
> +	}
> +
> +	DRM_INFO(DRV_NAME "_panel %ux%u@%u %ubpp dsi %udl - ready",
> +		 default_mode.hdisplay, default_mode.vdisplay,
> +		 default_mode.vrefresh,
> +		 mipi_dsi_pixel_format_to_bpp(dsi->format), dsi->lanes);
> +
> +	jh057n_debugfs_init(ctx);
> +	return 0;
> +
> +err:
> +	if (ctx->backlight)
> +		put_device(&ctx->backlight->dev);
No need for this check, it is handled by the devm_ infrastructure

> +	return ret;
> +
> +}
> +
> +static void jh057n_shutdown(struct mipi_dsi_device *dsi)
> +{
> +	struct jh057n *ctx = mipi_dsi_get_drvdata(dsi);
> +	int ret;
> +
> +	ret = jh057n_unprepare(&ctx->panel);
> +	if (ret < 0)
> +		DRM_DEV_ERROR(&dsi->dev, "Failed to unprepare panel: %d\n",
> +			      ret);
> +
> +	ret = jh057n_disable(&ctx->panel);
> +	if (ret < 0)
> +		DRM_DEV_ERROR(&dsi->dev, "Failed to disable panel: %d\n",
> +			      ret);
> +}
> +
> +static int jh057n_remove(struct mipi_dsi_device *dsi)
> +{
> +	struct jh057n *ctx = mipi_dsi_get_drvdata(dsi);
> +	int ret;
> +
> +	jh057n_shutdown(dsi);
> +
> +	ret = mipi_dsi_detach(dsi);
> +	if (ret < 0)
> +		DRM_DEV_ERROR(&dsi->dev, "Failed to detach from DSI host: %d\n",
> +			      ret);
> +
> +	drm_panel_remove(&ctx->panel);
> +
> +	if (ctx->backlight)
> +		put_device(&ctx->backlight->dev);
No need for this check, it is handled by the devm_ infrastructure

> +
> +	jh057n_debugfs_remove(ctx);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id jh057n_of_match[] = {
> +	{ .compatible = "rocktech,jh057n00900" },
> +	{ }
Consider replacing { } with
	{ /* Sentinel */ }
This is how it looks in many other drivers.

> +};
> +MODULE_DEVICE_TABLE(of, jh057n_of_match);
> +
> +static struct mipi_dsi_driver jh057n_driver = {
> +	.probe	= jh057n_probe,
> +	.remove = jh057n_remove,
> +	.shutdown = jh057n_shutdown,
> +	.driver = {
> +		.name = DRV_NAME "_panel",
> +		.of_match_table = jh057n_of_match,
> +	},
> +};
> +module_mipi_dsi_driver(jh057n_driver);
> +
> +MODULE_AUTHOR("Guido G?nther <agx@sigxcpu.org>");
> +MODULE_DESCRIPTION("DRM driver for Rocktech JH057N00900 MIPI DSI panel");
> +MODULE_LICENSE("GPL v2");
SPDX says this:
> +// SPDX-License-Identifier: GPL-2.0+

As far as I can tell this is not the same license.