Den 10.06.2021 15.25, skrev Linus Walleij:
> This adds a new driver for the Samsung DB7430 DPI display
> controller as controlled over SPI.
>
> Right now the only panel product we know that is using this
> display controller is the LMS397KF04 but there may be more.
>
> This is the first regular panel driver making use of the
> MIPI DBI helper library. The DBI "device" portions can not
> be used because that code assumes the use of a single
> regulator and specific timings around the reset pulse that
> do not match the DB7430 datasheet.
>
> Cc: Noralf Trønnes <noralf@xxxxxxxxxxx>
> Cc: Paul Cercueil <paul@xxxxxxxxxxxxxxx>
> Cc: Doug Anderson <dianders@xxxxxxxxxxxx>
> Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
> ---
> ChangeLog v3->v4:
> - Managed to make use of the in-kernel DBI support to
> conjure and send 9bit DBI SPI messages.
When I moved the DBI code out of tinydrm I split it up into an interface
part and a framebuffer part so panel drivers could use the interface
part like you have done here.
> - This cuts out a bit of overhead.
> - Deeper integration with the DBI library is not done, as
> assumes too much about the device, such as being used
> as a stand-alone framebuffer (this device is not).
> diff --git a/drivers/gpu/drm/panel/panel-samsung-db7430.c b/drivers/gpu/drm/panel/panel-samsung-db7430.c
> new file mode 100644
> index 000000000000..c11b3da65896
> --- /dev/null
> +++ b/drivers/gpu/drm/panel/panel-samsung-db7430.c
> +/**
> + * struct db7430 - state container for a panel controlled by the DB7430
> + * controller
> + */
> +struct db7430 {
> + /** @dev: the container device */
> + struct device *dev;
> + /** @dbi: the DBI bus abstraction handle */
> + struct mipi_dbi dbi;
> + /** @panel: the DRM panel instance for this device */
> + struct drm_panel panel;
> + /** @width: the width of this panel in mm */
> + u32 width;
> + /** @height: the height of this panel in mm */
> + u32 height;
> + /** @reset: reset GPIO line */
> + struct gpio_desc *reset;
You can use dbi->reset.
> + /** @regulators: VCCIO and VIO supply regulators */
> + struct regulator_bulk_data regulators[2];
> +};
> +static int db7430_probe(struct spi_device *spi)
> +{
> + struct device *dev = &spi->dev;
> + struct db7430 *db;
> + int ret;
> +
> + db = devm_kzalloc(dev, sizeof(*db), GFP_KERNEL);
> + if (!db)
> + return -ENOMEM;
> + db->dev = dev;
> +
> + /*
> + * VCI is the analog voltage supply
> + * VCCIO is the digital I/O voltage supply
> + */
> + db->regulators[0].supply = "vci";
> + db->regulators[1].supply = "vccio";
> + ret = devm_regulator_bulk_get(dev,
> + ARRAY_SIZE(db->regulators),
> + db->regulators);
> + if (ret)
> + return dev_err_probe(dev, ret, "failed to get regulators\n");
> +
> + db->reset = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
> + if (IS_ERR(db->reset)) {
> + ret = PTR_ERR(db->reset);
> + return dev_err_probe(dev, ret, "no RESET GPIO\n");
> + }
> +
> + spi->bits_per_word = 9;
Do you need to set this? The DBI helper sets it on the SPI transfer if
the SPI controller supports 9-bit or uses emulation code if not.
> + /* Preserve e.g. SPI_3WIRE setting */
> + spi->mode |= SPI_MODE_3;
You can use the DT properties 'spi-cpha' and 'spi-cpol' to set this.
> + ret = spi_setup(spi);
So I don't think you need to call spi_setup() here.
This code as-is will fail on a SPI controller that doesn't support 9
bits per word, and the emulation code in the DBI helper won't be utilised.
With the comments considered:
Acked-by: Noralf Trønnes <noralf@xxxxxxxxxxx>
Noralf.
> + if (ret < 0)
> + return dev_err_probe(dev, ret, "spi setup failed\n");
> +
> + ret = mipi_dbi_spi_init(spi, &db->dbi, NULL);
> + if (ret)
> + return dev_err_probe(dev, ret, "MIPI DBI init failed\n");
> +
> + drm_panel_init(&db->panel, dev, &db7430_drm_funcs,
> + DRM_MODE_CONNECTOR_DPI);
> +
> + /* FIXME: if no external backlight, use internal backlight */
> + ret = drm_panel_of_backlight(&db->panel);
> + if (ret)
> + return dev_err_probe(dev, ret, "failed to add backlight\n");
> +
> + spi_set_drvdata(spi, db);
> +
> + drm_panel_add(&db->panel);
> + dev_dbg(dev, "added panel\n");
> +
> + return 0;
> +}
