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Subject: Re: [PATCH v3 3/3] drm/tinydrm: add driver for ST7735R panels
To: David Lechner <david@lechnology.com>, dri-devel@lists.freedesktop.org,
        devicetree@vger.kernel.org
Cc: limor@ladyada.net, Linus Walleij <linus.walleij@linaro.org>,
        Rob Herring <robh+dt@kernel.org>, Mark Rutland <mark.rutland@arm.com>,
        linux-kernel@vger.kernel.org
References: <1513884233-31540-1-git-send-email-david@lechnology.com>
 <1513884233-31540-4-git-send-email-david@lechnology.com>
From: =?UTF-8?Q?Noralf_Tr=c3=b8nnes?= <noralf@tronnes.org>
Message-ID: <77b8eb04-4c25-5831-6132-735d52b2e730@tronnes.org>
Date: Sun, 31 Dec 2017 17:17:20 +0100
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Den 21.12.2017 20.23, skrev David Lechner:
> This adds a new driver for Sitronix ST7735R display panels.
>
> This has been tested using an Adafruit 1.8" TFT.
>
> Signed-off-by: David Lechner <david@lechnology.com>
> ---
>
> v3 changes:
> * Changed compatible string
> * use SPDX license header
> * Renamed mode struct to use panel name instead of controller name
>
> v2 changes:
> * Change delay from 10ms to 20ms to avoid checkpatch warning
> * Use mipi_dbi_pipe_enable()/mipi_dbi_pipe_disable() to reduce duplicated code
> * Rebase on drm-misc-next (tinydrm_lastclose => drm_fb_helper_lastclose)
> * Use mipi_dbi_debugfs_init
> * Add mipi->read_commands = NULL; since this display is write-only
<snip>
> diff --git a/drivers/gpu/drm/tinydrm/st7735r.c b/drivers/gpu/drm/tinydrm/st7735r.c
> new file mode 100644
> index 0000000..0b05b2c
> --- /dev/null
> +++ b/drivers/gpu/drm/tinydrm/st7735r.c
> @@ -0,0 +1,215 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * DRM driver for Sitronix ST7735R panels
> + *
> + * Copyright 2017 David Lechner <david@lechnology.com>
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/dma-buf.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/module.h>
> +#include <linux/property.h>
> +#include <linux/spi/spi.h>
> +#include <video/mipi_display.h>
> +
> +#include <drm/drm_fb_helper.h>
> +#include <drm/drm_gem_framebuffer_helper.h>
> +#include <drm/tinydrm/mipi-dbi.h>
> +#include <drm/tinydrm/tinydrm-helpers.h>
> +
> +#define ST7735R_FRMCTR1		0xb1
> +#define ST7735R_FRMCTR2		0xb2
> +#define ST7735R_FRMCTR3		0xb3
> +#define ST7735R_INVCTR		0xb4
> +#define ST7735R_PWCTR1		0xc0
> +#define ST7735R_PWCTR2		0xc1
> +#define ST7735R_PWCTR3		0xc2
> +#define ST7735R_PWCTR4		0xc3
> +#define ST7735R_PWCTR5		0xc4
> +#define ST7735R_VMCTR1		0xc5
> +#define ST7735R_GAMCTRP1	0xe0
> +#define ST7735R_GAMCTRN1	0xe1
> +
> +#define ST7735R_MY	BIT(7)
> +#define ST7735R_MX	BIT(6)
> +#define ST7735R_MV	BIT(5)
> +
> +static void st7735r_pipe_enable(struct drm_simple_display_pipe *pipe,
> +				struct drm_crtc_state *crtc_state)

This is confusing, you name the mode after the panel, but not the enable
function which has an initialization sequence that is also panel specific.

With .enable function named after the panel (and *_pipe_funcs):

Reviewed-by: Noralf Trønnes <noralf@tronnes.org>

> +{
> +	struct tinydrm_device *tdev = pipe_to_tinydrm(pipe);
> +	struct mipi_dbi *mipi = mipi_dbi_from_tinydrm(tdev);
> +	struct device *dev = tdev->drm->dev;
> +	int ret;
> +	u8 addr_mode;
> +
> +	DRM_DEBUG_KMS("\n");
> +
> +	mipi_dbi_hw_reset(mipi);
> +
> +	ret = mipi_dbi_command(mipi, MIPI_DCS_SOFT_RESET);
> +	if (ret) {
> +		DRM_DEV_ERROR(dev, "Error sending command %d\n", ret);
> +		return;
> +	}
> +
> +	msleep(150);
> +
> +	mipi_dbi_command(mipi, MIPI_DCS_EXIT_SLEEP_MODE);
> +	msleep(500);
> +
> +	mipi_dbi_command(mipi, ST7735R_FRMCTR1, 0x01, 0x2c, 0x2d);
> +	mipi_dbi_command(mipi, ST7735R_FRMCTR2, 0x01, 0x2c, 0x2d);
> +	mipi_dbi_command(mipi, ST7735R_FRMCTR3, 0x01, 0x2c, 0x2d, 0x01, 0x2c,
> +			 0x2d);
> +	mipi_dbi_command(mipi, ST7735R_INVCTR, 0x07);
> +	mipi_dbi_command(mipi, ST7735R_PWCTR1, 0xa2, 0x02, 0x84);
> +	mipi_dbi_command(mipi, ST7735R_PWCTR2, 0xc5);
> +	mipi_dbi_command(mipi, ST7735R_PWCTR3, 0x0a, 0x00);
> +	mipi_dbi_command(mipi, ST7735R_PWCTR4, 0x8a, 0x2a);
> +	mipi_dbi_command(mipi, ST7735R_PWCTR5, 0x8a, 0xee);
> +	mipi_dbi_command(mipi, ST7735R_VMCTR1, 0x0e);
> +	mipi_dbi_command(mipi, MIPI_DCS_EXIT_INVERT_MODE);
> +	switch (mipi->rotation) {
> +	default:
> +		addr_mode = ST7735R_MX | ST7735R_MY;
> +		break;
> +	case 90:
> +		addr_mode = ST7735R_MX | ST7735R_MV;
> +		break;
> +	case 180:
> +		addr_mode = 0;
> +		break;
> +	case 270:
> +		addr_mode = ST7735R_MY | ST7735R_MV;
> +		break;
> +	}
> +	mipi_dbi_command(mipi, MIPI_DCS_SET_ADDRESS_MODE, addr_mode);
> +	mipi_dbi_command(mipi, MIPI_DCS_SET_PIXEL_FORMAT,
> +			 MIPI_DCS_PIXEL_FMT_16BIT);
> +	mipi_dbi_command(mipi, ST7735R_GAMCTRP1, 0x0f, 0x1a, 0x0f, 0x18, 0x2f,
> +			 0x28, 0x20, 0x22, 0x1f, 0x1b, 0x23, 0x37, 0x00, 0x07,
> +			 0x02, 0x10);
> +	mipi_dbi_command(mipi, ST7735R_GAMCTRN1, 0x0f, 0x1b, 0x0f, 0x17, 0x33,
> +			 0x2c, 0x29, 0x2e, 0x30, 0x30, 0x39, 0x3f, 0x00, 0x07,
> +			 0x03, 0x10);
> +	mipi_dbi_command(mipi, MIPI_DCS_SET_DISPLAY_ON);
> +
> +	msleep(100);
> +
> +	mipi_dbi_command(mipi, MIPI_DCS_ENTER_NORMAL_MODE);
> +
> +	msleep(20);
> +
> +	mipi_dbi_pipe_enable(pipe, crtc_state);
> +}
> +
> +static const struct drm_simple_display_pipe_funcs st7735r_pipe_funcs = {
> +	.enable		= st7735r_pipe_enable,
> +	.disable	= mipi_dbi_pipe_disable,
> +	.update		= tinydrm_display_pipe_update,
> +	.prepare_fb	= tinydrm_display_pipe_prepare_fb,
> +};
> +
> +static const struct drm_display_mode jd_t18003_t01_mode = {
> +	TINYDRM_MODE(128, 160, 28, 35),
> +};
> +
> +DEFINE_DRM_GEM_CMA_FOPS(st7735r_fops);
> +
> +static struct drm_driver st7735r_driver = {
> +	.driver_features	= DRIVER_GEM | DRIVER_MODESET | DRIVER_PRIME |
> +				  DRIVER_ATOMIC,
> +	.fops			= &st7735r_fops,
> +	TINYDRM_GEM_DRIVER_OPS,
> +	.lastclose		= drm_fb_helper_lastclose,
> +	.debugfs_init		= mipi_dbi_debugfs_init,
> +	.name			= "st7735r",
> +	.desc			= "Sitronix ST7735R",
> +	.date			= "20171128",
> +	.major			= 1,
> +	.minor			= 0,
> +};
> +
> +static const struct of_device_id st7735r_of_match[] = {
> +	{ .compatible = "jianda,jd-t18003-t01" },
> +	{},
> +};
> +MODULE_DEVICE_TABLE(of, st7735r_of_match);
> +
> +static const struct spi_device_id st7735r_id[] = {
> +	{ "jd-t18003-t01", 0 },
> +	{ },
> +};
> +MODULE_DEVICE_TABLE(spi, st7735r_id);
> +
> +static int st7735r_probe(struct spi_device *spi)
> +{
> +	struct device *dev = &spi->dev;
> +	struct mipi_dbi *mipi;
> +	struct gpio_desc *dc;
> +	u32 rotation = 0;
> +	int ret;
> +
> +	mipi = devm_kzalloc(dev, sizeof(*mipi), GFP_KERNEL);
> +	if (!mipi)
> +		return -ENOMEM;
> +
> +	mipi->reset = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
> +	if (IS_ERR(mipi->reset)) {
> +		DRM_DEV_ERROR(dev, "Failed to get gpio 'reset'\n");
> +		return PTR_ERR(mipi->reset);
> +	}
> +
> +	dc = devm_gpiod_get(dev, "dc", GPIOD_OUT_LOW);
> +	if (IS_ERR(dc)) {
> +		DRM_DEV_ERROR(dev, "Failed to get gpio 'dc'\n");
> +		return PTR_ERR(dc);
> +	}
> +
> +	mipi->backlight = tinydrm_of_find_backlight(dev);
> +	if (IS_ERR(mipi->backlight))
> +		return PTR_ERR(mipi->backlight);
> +
> +	device_property_read_u32(dev, "rotation", &rotation);
> +
> +	ret = mipi_dbi_spi_init(spi, mipi, dc);
> +	if (ret)
> +		return ret;
> +
> +	/* Cannot read from Adafruit 1.8" display via SPI */
> +	mipi->read_commands = NULL;
> +
> +	ret = mipi_dbi_init(&spi->dev, mipi, &st7735r_pipe_funcs,
> +			    &st7735r_driver, &jd_t18003_t01_mode, rotation);
> +	if (ret)
> +		return ret;
> +
> +	spi_set_drvdata(spi, mipi);
> +
> +	return devm_tinydrm_register(&mipi->tinydrm);
> +}
> +
> +static void st7735r_shutdown(struct spi_device *spi)
> +{
> +	struct mipi_dbi *mipi = spi_get_drvdata(spi);
> +
> +	tinydrm_shutdown(&mipi->tinydrm);
> +}
> +
> +static struct spi_driver st7735r_spi_driver = {
> +	.driver = {
> +		.name = "st7735r",
> +		.owner = THIS_MODULE,
> +		.of_match_table = st7735r_of_match,
> +	},
> +	.id_table = st7735r_id,
> +	.probe = st7735r_probe,
> +	.shutdown = st7735r_shutdown,
> +};
> +module_spi_driver(st7735r_spi_driver);
> +
> +MODULE_DESCRIPTION("Sitronix ST7735R DRM driver");
> +MODULE_AUTHOR("David Lechner <david@lechnology.com>");
> +MODULE_LICENSE("GPL");