Re: [PATCH v6 10/14] drm/panel: add S6E3FA0 driver

[Thierry Reding <thierry.reding@gmail.com>]

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On Thu, Jul 17, 2014 at 06:01:25PM +0900, YoungJun Cho wrote:
[...]
> diff --git a/drivers/gpu/drm/panel/panel-s6e3fa0.c b/drivers/gpu/drm/panel/panel-s6e3fa0.c
[...]
> +/* Manufacturer Command Set */
> +#define MCS_GLOBAL_PARAMETER	0xb0
> +#define MCS_AID			0xb2
> +#define MCS_ELVSSOPT		0xb6
> +#define MCS_TEMPERATURE_SET	0xb8
> +#define MCS_PENTILE_CTRL	0xc0
> +#define MCS_GAMMA_MODE		0xca
> +#define MCS_VDDM		0xd7
> +#define MCS_ALS			0xe3
> +#define MCS_ERR_FG		0xed
> +#define MCS_KEY_LEV1		0xf0
> +#define MCS_GAMMA_UPDATE	0xf7
> +#define MCS_KEY_LEV2		0xfc
> +#define MCS_RE			0xfe
> +#define MCS_TOUT2_HSYNC		0xff
> +
> +/* Content Adaptive Brightness Control */
> +#define DCS_WRITE_CABC		0x55

Is this not a manufacturer specific command? I couldn't find it in the
DSI or DCS specifications, but it sounds like something standard (also
indicated by the DCS_ prefix). Can you point out the specification for
this?

> +#define MTP_ID_LEN		3
> +#define GAMMA_LEVEL_NUM		30
> +
> +#define DEFAULT_VDDM_VAL	0x15
> +
> +struct s6e3fa0 {
> +	struct device			*dev;
> +	struct drm_panel		panel;
> +
> +	struct regulator_bulk_data	supplies[2];
> +	struct gpio_desc		*reset_gpio;
> +	struct videomode		vm;
> +
> +	unsigned int			power_on_delay;
> +	unsigned int			reset_delay;
> +	unsigned int			init_delay;
> +	unsigned int			width_mm;
> +	unsigned int			height_mm;
> +
> +	unsigned char			id;
> +	unsigned char			vddm;
> +	unsigned int			brightness;
> +};

Please don't use this kind of artificial padding. A simple space will
do.

> +
> +#define panel_to_s6e3fa0(p) container_of(p, struct s6e3fa0, panel)

Please turn this into a function so we can get proper type checking.

> +
> +/* VDD Memory Lookup Table contains pairs of {ReadValue, WriteValue} */
> +static const unsigned char s6e3fa0_vddm_lut[][2] = {
> +	{0x00, 0x0d}, {0x01, 0x0d}, {0x02, 0x0e}, {0x03, 0x0f}, {0x04, 0x10},
> +	{0x05, 0x11}, {0x06, 0x12}, {0x07, 0x13}, {0x08, 0x14}, {0x09, 0x15},
> +	{0x0a, 0x16}, {0x0b, 0x17}, {0x0c, 0x18}, {0x0d, 0x19}, {0x0e, 0x1a},
> +	{0x0f, 0x1b}, {0x10, 0x1c}, {0x11, 0x1d}, {0x12, 0x1e}, {0x13, 0x1f},
> +	{0x14, 0x20}, {0x15, 0x21}, {0x16, 0x22}, {0x17, 0x23}, {0x18, 0x24},
> +	{0x19, 0x25}, {0x1a, 0x26}, {0x1b, 0x27}, {0x1c, 0x28}, {0x1d, 0x29},
> +	{0x1e, 0x2a}, {0x1f, 0x2b}, {0x20, 0x2c}, {0x21, 0x2d}, {0x22, 0x2e},
> +	{0x23, 0x2f}, {0x24, 0x30}, {0x25, 0x31}, {0x26, 0x32}, {0x27, 0x33},
> +	{0x28, 0x34}, {0x29, 0x35}, {0x2a, 0x36}, {0x2b, 0x37}, {0x2c, 0x38},
> +	{0x2d, 0x39}, {0x2e, 0x3a}, {0x2f, 0x3b}, {0x30, 0x3c}, {0x31, 0x3d},
> +	{0x32, 0x3e}, {0x33, 0x3f}, {0x34, 0x3f}, {0x35, 0x3f}, {0x36, 0x3f},
> +	{0x37, 0x3f}, {0x38, 0x3f}, {0x39, 0x3f}, {0x3a, 0x3f}, {0x3b, 0x3f},
> +	{0x3c, 0x3f}, {0x3d, 0x3f}, {0x3e, 0x3f}, {0x3f, 0x3f}, {0x40, 0x0c},
> +	{0x41, 0x0b}, {0x42, 0x0a}, {0x43, 0x09}, {0x44, 0x08}, {0x45, 0x07},
> +	{0x46, 0x06}, {0x47, 0x05}, {0x48, 0x04}, {0x49, 0x03}, {0x4a, 0x02},
> +	{0x4b, 0x01}, {0x4c, 0x40}, {0x4d, 0x41}, {0x4e, 0x42}, {0x4f, 0x43},
> +	{0x50, 0x44}, {0x51, 0x45}, {0x52, 0x46}, {0x53, 0x47}, {0x54, 0x48},
> +	{0x55, 0x49}, {0x56, 0x4a}, {0x57, 0x4b}, {0x58, 0x4c}, {0x59, 0x4d},
> +	{0x5a, 0x4e}, {0x5b, 0x4f}, {0x5c, 0x50}, {0x5d, 0x51}, {0x5e, 0x52},
> +	{0x5f, 0x53}, {0x60, 0x54}, {0x61, 0x55}, {0x62, 0x56}, {0x63, 0x57},
> +	{0x64, 0x58}, {0x65, 0x59}, {0x66, 0x5a}, {0x67, 0x5b}, {0x68, 0x5c},
> +	{0x69, 0x5d}, {0x6a, 0x5e}, {0x6b, 0x5f}, {0x6c, 0x60}, {0x6d, 0x61},
> +	{0x6e, 0x62}, {0x6f, 0x63}, {0x70, 0x64}, {0x71, 0x65}, {0x72, 0x66},
> +	{0x73, 0x67}, {0x74, 0x68}, {0x75, 0x69}, {0x76, 0x6a}, {0x77, 0x6b},
> +	{0x78, 0x6c}, {0x79, 0x6d}, {0x7a, 0x6e}, {0x7b, 0x6f}, {0x7c, 0x70},
> +	{0x7d, 0x71}, {0x7e, 0x72}, {0x7f, 0x73},
> +};

What's this used for?

> +static int s6e3fa0_dcs_read(struct s6e3fa0 *ctx, unsigned char cmd,
> +							void *data, size_t len)
> +{
> +	struct mipi_dsi_device *dsi = to_mipi_dsi_device(ctx->dev);
> +
> +	return mipi_dsi_dcs_read(dsi, dsi->channel, cmd, data, len);
> +}
> +
> +static void s6e3fa0_dcs_write(struct s6e3fa0 *ctx, const void *data, size_t len)
> +{
> +	struct mipi_dsi_device *dsi = to_mipi_dsi_device(ctx->dev);
> +
> +	mipi_dsi_dcs_write(dsi, dsi->channel, data, len);
> +}

Both mipi_dsi_dcs_read() and mipi_dsi_dcs_write() return error codes on
failure. Why are you silently ignoring them?

> +#define s6e3fa0_dcs_write_seq(ctx, seq...)				\
> +do {									\
> +	const unsigned char d[] = { seq };				\
> +	BUILD_BUG_ON_MSG(ARRAY_SIZE(d) > 64, "too big seq for stack");	\
> +	s6e3fa0_dcs_write(ctx, d, ARRAY_SIZE(d));			\
> +} while (0)
> +
> +#define s6e3fa0_dcs_write_seq_static(ctx, seq...)			\
> +do {									\
> +	static const unsigned char d[] = { seq };			\
> +	s6e3fa0_dcs_write(ctx, d, ARRAY_SIZE(d));			\
> +} while (0)

I've had this discussion with Andrzej before and I'm still not convinced
that this is a useful macro.

At least they should propagate the error code, though.

> +static void s6e3fa0_set_maximum_return_packet_size(struct s6e3fa0 *ctx,
> +							unsigned int size)
> +{
> +	struct mipi_dsi_device *dsi = to_mipi_dsi_device(ctx->dev);
> +	const struct mipi_dsi_host_ops *ops = dsi->host->ops;
> +
> +	if (ops && ops->transfer) {
> +		unsigned char buf[] = {size, 0};
> +		struct mipi_dsi_msg msg = {
> +			.channel = dsi->channel,
> +			.type = MIPI_DSI_SET_MAXIMUM_RETURN_PACKET_SIZE,
> +			.tx_len = sizeof(buf),
> +			.tx_buf = buf
> +		};
> +
> +		ops->transfer(dsi->host, &msg);
> +	}
> +}

The Set Maximum Return Packet Size command is a standard command, so
please turn that into a generic function exposed by the DSI core.

> +static void s6e3fa0_read_mtp_id(struct s6e3fa0 *ctx)
> +{
> +	unsigned char id[MTP_ID_LEN];
> +	int ret;
> +
> +	s6e3fa0_set_maximum_return_packet_size(ctx, MTP_ID_LEN);
> +	ret = s6e3fa0_dcs_read(ctx, MIPI_DCS_GET_DISPLAY_ID, id, MTP_ID_LEN);

This also looks like a standard DCS command. I can't find it in either
v1.01 nor v1.02 of the specification, though. Do you know where it's
specified?

> +static void s6e3fa0_set_te_on(struct s6e3fa0 *ctx)
> +{
> +	s6e3fa0_dcs_write_seq_static(ctx, MIPI_DCS_SET_TEAR_ON, 0x00);
> +}

This is also a standard DCS command.

> +static int s6e3fa0_power_off(struct s6e3fa0 *ctx)
> +{
> +	gpiod_set_value(ctx->reset_gpio, 0);

Setting the reset GPIO to 0 for power off? Shouldn't this be 1 and the
polarity be specified in the GPIO specifier?

> +static void s6e3fa0_set_sequence(struct s6e3fa0 *ctx)
> +{
> +	s6e3fa0_apply_level_1_key(ctx);
> +	s6e3fa0_dcs_write_seq_static(ctx, MIPI_DCS_EXIT_SLEEP_MODE);
> +	msleep(20);
> +
> +	s6e3fa0_read_mtp_id(ctx);
> +	s6e3fa0_read_vddm(ctx);
> +
> +	s6e3fa0_panel_init(ctx);
> +
> +	s6e3fa0_dcs_write_seq_static(ctx, MIPI_DCS_SET_DISPLAY_ON);
> +}
> +
> +static int s6e3fa0_disable(struct drm_panel *panel)
> +{
> +	struct s6e3fa0 *ctx = panel_to_s6e3fa0(panel);
> +
> +	s6e3fa0_dcs_write_seq_static(ctx, MIPI_DCS_SET_DISPLAY_OFF);
> +	msleep(35);
> +	s6e3fa0_dcs_write_seq_static(ctx, MIPI_DCS_ENTER_SLEEP_MODE);
> +	msleep(120);
> +
> +	return s6e3fa0_power_off(ctx);
> +}

The SET_DISPLAY_{ON,OFF} and {ENTER,EXIT}_SLEEP_MODE are standard
commands, too.

> +static int s6e3fa0_probe(struct mipi_dsi_device *dsi)
> +{
> +	struct device *dev = &dsi->dev;
> +	struct s6e3fa0 *ctx;
> +	struct gpio_desc *det_gpio;
> +	int ret, te_gpio;
> +
> +	ctx = devm_kzalloc(dev, sizeof(struct s6e3fa0), GFP_KERNEL);

sizeof(*ctx)

> +	det_gpio = devm_gpiod_get(dev, "det");
> +	if (IS_ERR(det_gpio)) {
> +		dev_err(dev, "failed to get det gpio: %ld\n",
> +				PTR_ERR(det_gpio));
> +		return PTR_ERR(det_gpio);
> +	}
> +	ret = gpiod_direction_input(det_gpio);
> +	if (ret < 0) {
> +		dev_err(dev, "failed to configure det gpio: %d\n", ret);
> +		return ret;
> +	}
> +	ret = devm_request_irq(dev, gpiod_to_irq(det_gpio),
> +				s6e3fa0_det_interrupt, IRQF_TRIGGER_FALLING,
> +				"oled-det", ctx);
> +	if (ret) {
> +		dev_err(dev, "failed to request det irq: %d\n", ret);
> +		return ret;
> +	}
> +
> +	te_gpio = of_get_named_gpio(dev->of_node, "te-gpios", 0);

Why doesn't this use the gpiod_* API like the other GPIOs?

> +static struct of_device_id s6e3fa0_of_match[] = {

Should be static const.

Thierry

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