diff mbox series

[v5] drm/panel: db7430: Add driver for Samsung DB7430

Message ID 20210610220527.366432-1-linus.walleij@linaro.org (mailing list archive)
State New, archived
Headers show
Series [v5] drm/panel: db7430: Add driver for Samsung DB7430 | expand

Commit Message

Linus Walleij June 10, 2021, 10:05 p.m. UTC
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: Paul Cercueil <paul@crapouillou.net>
Cc: Doug Anderson <dianders@chromium.org>
Acked-by: Noralf Trønnes <noralf@tronnes.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
---
ChangeLog v4->v5:
- Drop the SPI hardcoding to 9 BPW, so the DBI emulation
  will be utilized if needed.
- Drop the MODE_3 setting: we can set this up in the DTS
  instead.
- Collect Noralf's ACK.
ChangeLog v3->v4:
- Managed to make use of the in-kernel DBI support to
  conjure and send 9bit DBI SPI messages.
- 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).
ChangeLog v2->v3:
- Fix some minor comments and formatting.
- Print an error if the DCS sequence write fails.
- Set BPC (bits per color) to 8 on the display_info. Some
  drivers may need this.
ChangeLog v1->v2:
- Rename driver and variables with the db7430_* prefix instead
  of lms397kf04 as there may be more display products out there
  using this display controller. Also change Kconfig symbol.
- Push doc comments together on one line where possible.
- Rename DB7430_MANUFACTURER_CMD to DB7430_ACCESS_PROT_OFF
- Return error from regulator_bulk_disable() down to
  db7430_unprepare() and propagate.
- Use usleep_range(1000, 5000) instead of msleep(1)
- Shorten prepare/unprepare callbacks by more compact code.
- Use devm_err_probe() and provide proper probe errors all
  the way through the probe() function.
---
 MAINTAINERS                                  |   7 +
 drivers/gpu/drm/panel/Kconfig                |  10 +
 drivers/gpu/drm/panel/Makefile               |   1 +
 drivers/gpu/drm/panel/panel-samsung-db7430.c | 347 +++++++++++++++++++
 4 files changed, 365 insertions(+)
 create mode 100644 drivers/gpu/drm/panel/panel-samsung-db7430.c

Comments

Doug Anderson June 10, 2021, 10:30 p.m. UTC | #1
Hi,

On Thu, Jun 10, 2021 at 3:07 PM Linus Walleij <linus.walleij@linaro.org> wrote:
>
> @@ -0,0 +1,347 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Panel driver for the Samsung LMS397KF04 480x800 DPI RGB panel.
> + * According to the data sheet the display controller is called DB7430.
> + * Found in the Samsung Galaxy Beam GT-I8350 mobile phone.
> + * Linus Walleij <linus.walleij@linaro.org>
> + */
> +#include <drm/drm_modes.h>
> +#include <drm/drm_mipi_dbi.h>

nit that "mipi" sorts before "modes"


> +static int db7430_power_on(struct db7430 *db)
> +{
> +       struct mipi_dbi *dbi = &db->dbi;
> +       int ret;
> +
> +       /* Power up */
> +       ret = regulator_bulk_enable(ARRAY_SIZE(db->regulators),
> +                                   db->regulators);
> +       if (ret) {
> +               dev_err(db->dev, "failed to enable regulators: %d\n", ret);
> +               return ret;
> +       }
> +       msleep(50);
> +
> +       /* Assert reset >=1 ms */
> +       gpiod_set_value_cansleep(db->reset, 1);
> +       usleep_range(1000, 5000);
> +       /* De-assert reset */
> +       gpiod_set_value_cansleep(db->reset, 0);
> +       /* Wait >= 10 ms */
> +       msleep(10);
> +       dev_dbg(db->dev, "de-asserted RESET\n");
> +
> +       /*
> +        * This is set to 0x0a (RGB/BGR order + horizontal flip) in order
> +        * to make the display behave normally. If this is not set the displays
> +        * normal output behaviour is horizontally flipped and BGR ordered. Do
> +        * it twice because the first message doesn't always "take".
> +        */
> +       mipi_dbi_command(dbi, MIPI_DCS_SET_ADDRESS_MODE, 0x0a);

I would still prefer it if there was some type of error checking since
SPI commands can fail and could potentially fail silently. What about
at least this (untested):

#define db7430_dbi_cmd(_db, _cmd, _seq...) \
  do {
    int _ret = mipi_dbi_command(_db->dbi, _cmd, _seq);
    if (_ret)
      dev_warn(_db->dev, "DBI cmd %d failed (%d)\n", _cmd, _ret);
  } while (0)

Then at least you know _something_ will show up in the logs if there's
a transfer failure instead of silence?

If you truly don't want the error checking then I guess I won't
insist, but it feels like the kind of thing that will bite someone
eventually... In any case, I'm happy to add this now (especially since
the DBI stuff is Acked now).

Reviewed-by: Douglas Anderson <dianders@chromium.org>

I presume that you'd commit it to drm-misc yourself?

-Doug
Linus Walleij June 10, 2021, 10:38 p.m. UTC | #2
On Fri, Jun 11, 2021 at 12:30 AM Doug Anderson <dianders@chromium.org> wrote:

> > +       mipi_dbi_command(dbi, MIPI_DCS_SET_ADDRESS_MODE, 0x0a);
>
> I would still prefer it if there was some type of error checking since
> SPI commands can fail and could potentially fail silently. What about
> at least this (untested):
>
> #define db7430_dbi_cmd(_db, _cmd, _seq...) \
>   do {
>     int _ret = mipi_dbi_command(_db->dbi, _cmd, _seq);
>     if (_ret)
>       dev_warn(_db->dev, "DBI cmd %d failed (%d)\n", _cmd, _ret);
>   } while (0)
>
> Then at least you know _something_ will show up in the logs if there's
> a transfer failure instead of silence?
>
> If you truly don't want the error checking then I guess I won't
> insist, but it feels like the kind of thing that will bite someone
> eventually... In any case, I'm happy to add this now (especially since
> the DBI stuff is Acked now).

This looks more like something that should be done in
mipi_dbi_command() in include/drm/drm_mipi_dbi.h
which claims:

 * Returns:
 * Zero on success, negative error code on failure.
 */

But no it does not return anything:

#define mipi_dbi_command(dbi, cmd, seq...) \
({ \
        const u8 d[] = { seq }; \
        mipi_dbi_command_stackbuf(dbi, cmd, d, ARRAY_SIZE(d)); \
})

I'll fix up the include and apply then we can think about
what to do with mipi_dbi_command().

Yours,
Linus Walleij
Doug Anderson June 10, 2021, 10:42 p.m. UTC | #3
Hi,

On Thu, Jun 10, 2021 at 3:39 PM Linus Walleij <linus.walleij@linaro.org> wrote:
>
> On Fri, Jun 11, 2021 at 12:30 AM Doug Anderson <dianders@chromium.org> wrote:
>
> > > +       mipi_dbi_command(dbi, MIPI_DCS_SET_ADDRESS_MODE, 0x0a);
> >
> > I would still prefer it if there was some type of error checking since
> > SPI commands can fail and could potentially fail silently. What about
> > at least this (untested):
> >
> > #define db7430_dbi_cmd(_db, _cmd, _seq...) \
> >   do {
> >     int _ret = mipi_dbi_command(_db->dbi, _cmd, _seq);
> >     if (_ret)
> >       dev_warn(_db->dev, "DBI cmd %d failed (%d)\n", _cmd, _ret);
> >   } while (0)
> >
> > Then at least you know _something_ will show up in the logs if there's
> > a transfer failure instead of silence?
> >
> > If you truly don't want the error checking then I guess I won't
> > insist, but it feels like the kind of thing that will bite someone
> > eventually... In any case, I'm happy to add this now (especially since
> > the DBI stuff is Acked now).
>
> This looks more like something that should be done in
> mipi_dbi_command() in include/drm/drm_mipi_dbi.h
> which claims:
>
>  * Returns:
>  * Zero on success, negative error code on failure.
>  */
>
> But no it does not return anything:
>
> #define mipi_dbi_command(dbi, cmd, seq...) \
> ({ \
>         const u8 d[] = { seq }; \
>         mipi_dbi_command_stackbuf(dbi, cmd, d, ARRAY_SIZE(d)); \
> })
>
> I'll fix up the include and apply then we can think about
> what to do with mipi_dbi_command().

Are you sure that doesn't work? Isn't the return value of a macro the
last expression? In this case the return value of
mipi_dbi_command_stackbuf() should just flow through.

-Doug
Linus Walleij June 10, 2021, 11 p.m. UTC | #4
On Fri, Jun 11, 2021 at 12:42 AM Doug Anderson <dianders@chromium.org> wrote:
> On Thu, Jun 10, 2021 at 3:39 PM Linus Walleij <linus.walleij@linaro.org> wrote:


> > #define mipi_dbi_command(dbi, cmd, seq...) \
> > ({ \
> >         const u8 d[] = { seq }; \
> >         mipi_dbi_command_stackbuf(dbi, cmd, d, ARRAY_SIZE(d)); \
> > })
> >
> > I'll fix up the include and apply then we can think about
> > what to do with mipi_dbi_command().
>
> Are you sure that doesn't work? Isn't the return value of a macro the
> last expression? In this case the return value of
> mipi_dbi_command_stackbuf() should just flow through.

w00t I didn't know that.

And I like to think of the macro processor as essentially just
inserting the content of the macro at the cursor.

But arguably it *should* rather be fixed in this macro though?
It is used in the same way in all other drivers as well.

Yours,
Linus Walleij
Doug Anderson June 10, 2021, 11:05 p.m. UTC | #5
Hi,

On Thu, Jun 10, 2021 at 4:01 PM Linus Walleij <linus.walleij@linaro.org> wrote:
>
> On Fri, Jun 11, 2021 at 12:42 AM Doug Anderson <dianders@chromium.org> wrote:
> > On Thu, Jun 10, 2021 at 3:39 PM Linus Walleij <linus.walleij@linaro.org> wrote:
>
>
> > > #define mipi_dbi_command(dbi, cmd, seq...) \
> > > ({ \
> > >         const u8 d[] = { seq }; \
> > >         mipi_dbi_command_stackbuf(dbi, cmd, d, ARRAY_SIZE(d)); \
> > > })
> > >
> > > I'll fix up the include and apply then we can think about
> > > what to do with mipi_dbi_command().
> >
> > Are you sure that doesn't work? Isn't the return value of a macro the
> > last expression? In this case the return value of
> > mipi_dbi_command_stackbuf() should just flow through.
>
> w00t I didn't know that.
>
> And I like to think of the macro processor as essentially just
> inserting the content of the macro at the cursor.
>
> But arguably it *should* rather be fixed in this macro though?
> It is used in the same way in all other drivers as well.

You want the mipi_dbi_command() to do the error checking and print the
message? Two downsides:

1. What if someone didn't _want_ the message printed? They might want
to try to handle things more elegantly, like maybe fail the function?

2. Currently the mipi_dbi_command() macro doesn't have access to a
"dev" pointer so it wouldn't be able to print as nice of an error as
you can.

That being said, I wouldn't object to introducing a macro next to
mipi_dbi_command() that also takes a dev pointer, prints an error, and
doesn't return a value.

-Doug
diff mbox series

Patch

diff --git a/MAINTAINERS b/MAINTAINERS
index bd7aff0c120f..6ff4777b1018 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -5857,6 +5857,13 @@  S:	Maintained
 F:	Documentation/devicetree/bindings/display/panel/raydium,rm67191.yaml
 F:	drivers/gpu/drm/panel/panel-raydium-rm67191.c
 
+DRM DRIVER FOR SAMSUNG DB7430 PANELS
+M:	Linus Walleij <linus.walleij@linaro.org>
+S:	Maintained
+T:	git git://anongit.freedesktop.org/drm/drm-misc
+F:	Documentation/devicetree/bindings/display/panel/samsung,lms397kf04.yaml
+F:	drivers/gpu/drm/panel/panel-samsung-db7430.c
+
 DRM DRIVER FOR SITRONIX ST7703 PANELS
 M:	Guido Günther <agx@sigxcpu.org>
 R:	Purism Kernel Team <kernel@puri.sm>
diff --git a/drivers/gpu/drm/panel/Kconfig b/drivers/gpu/drm/panel/Kconfig
index 4894913936e9..6d1b90f4f2bb 100644
--- a/drivers/gpu/drm/panel/Kconfig
+++ b/drivers/gpu/drm/panel/Kconfig
@@ -342,6 +342,16 @@  config DRM_PANEL_RONBO_RB070D30
 	  Say Y here if you want to enable support for Ronbo Electronics
 	  RB070D30 1024x600 DSI panel.
 
+config DRM_PANEL_SAMSUNG_DB7430
+	tristate "Samsung DB7430-based DPI panels"
+	depends on OF && SPI && GPIOLIB
+	depends on BACKLIGHT_CLASS_DEVICE
+	select DRM_MIPI_DBI
+	help
+	  Say Y here if you want to enable support for the Samsung
+	  DB7430 DPI display controller used in such devices as the
+	  LMS397KF04 480x800 DPI panel.
+
 config DRM_PANEL_SAMSUNG_S6D16D0
 	tristate "Samsung S6D16D0 DSI video mode panel"
 	depends on OF
diff --git a/drivers/gpu/drm/panel/Makefile b/drivers/gpu/drm/panel/Makefile
index cae4d976c069..a350e0990d17 100644
--- a/drivers/gpu/drm/panel/Makefile
+++ b/drivers/gpu/drm/panel/Makefile
@@ -33,6 +33,7 @@  obj-$(CONFIG_DRM_PANEL_RASPBERRYPI_TOUCHSCREEN) += panel-raspberrypi-touchscreen
 obj-$(CONFIG_DRM_PANEL_RAYDIUM_RM67191) += panel-raydium-rm67191.o
 obj-$(CONFIG_DRM_PANEL_RAYDIUM_RM68200) += panel-raydium-rm68200.o
 obj-$(CONFIG_DRM_PANEL_RONBO_RB070D30) += panel-ronbo-rb070d30.o
+obj-$(CONFIG_DRM_PANEL_SAMSUNG_DB7430) += panel-samsung-db7430.o
 obj-$(CONFIG_DRM_PANEL_SAMSUNG_LD9040) += panel-samsung-ld9040.o
 obj-$(CONFIG_DRM_PANEL_SAMSUNG_S6D16D0) += panel-samsung-s6d16d0.o
 obj-$(CONFIG_DRM_PANEL_SAMSUNG_S6E3HA2) += panel-samsung-s6e3ha2.o
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..fe58263bd9cd
--- /dev/null
+++ b/drivers/gpu/drm/panel/panel-samsung-db7430.c
@@ -0,0 +1,347 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Panel driver for the Samsung LMS397KF04 480x800 DPI RGB panel.
+ * According to the data sheet the display controller is called DB7430.
+ * Found in the Samsung Galaxy Beam GT-I8350 mobile phone.
+ * Linus Walleij <linus.walleij@linaro.org>
+ */
+#include <drm/drm_modes.h>
+#include <drm/drm_mipi_dbi.h>
+#include <drm/drm_panel.h>
+
+#include <linux/delay.h>
+#include <linux/gpio/consumer.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/media-bus-format.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/regulator/consumer.h>
+#include <linux/spi/spi.h>
+
+#include <video/mipi_display.h>
+
+#define DB7430_ACCESS_PROT_OFF		0xb0
+#define DB7430_UNKNOWN_B4		0xb4
+#define DB7430_USER_SELECT		0xb5
+#define DB7430_UNKNOWN_B7		0xb7
+#define DB7430_UNKNOWN_B8		0xb8
+#define DB7430_PANEL_DRIVING		0xc0
+#define DB7430_SOURCE_CONTROL		0xc1
+#define DB7430_GATE_INTERFACE		0xc4
+#define DB7430_DISPLAY_H_TIMING		0xc5
+#define DB7430_RGB_SYNC_OPTION		0xc6
+#define DB7430_GAMMA_SET_RED		0xc8
+#define DB7430_GAMMA_SET_GREEN		0xc9
+#define DB7430_GAMMA_SET_BLUE		0xca
+#define DB7430_BIAS_CURRENT_CTRL	0xd1
+#define DB7430_DDV_CTRL			0xd2
+#define DB7430_GAMMA_CTRL_REF		0xd3
+#define DB7430_UNKNOWN_D4		0xd4
+#define DB7430_DCDC_CTRL		0xd5
+#define DB7430_VCL_CTRL			0xd6
+#define DB7430_UNKNOWN_F8		0xf8
+#define DB7430_UNKNOWN_FC		0xfc
+
+#define DATA_MASK	0x100
+
+/**
+ * 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;
+	/** @regulators: VCCIO and VIO supply regulators */
+	struct regulator_bulk_data regulators[2];
+};
+
+static const struct drm_display_mode db7430_480_800_mode = {
+	/*
+	 * 31 ns period min (htotal*vtotal*vrefresh)/1000
+	 * gives a Vrefresh of ~71 Hz.
+	 */
+	.clock = 32258,
+	.hdisplay = 480,
+	.hsync_start = 480 + 10,
+	.hsync_end = 480 + 10 + 4,
+	.htotal = 480 + 10 + 4 + 40,
+	.vdisplay = 800,
+	.vsync_start = 800 + 6,
+	.vsync_end = 800 + 6 + 1,
+	.vtotal = 800 + 6 + 1 + 7,
+	.width_mm = 53,
+	.height_mm = 87,
+	.flags = DRM_MODE_FLAG_NVSYNC | DRM_MODE_FLAG_NHSYNC,
+};
+
+static inline struct db7430 *to_db7430(struct drm_panel *panel)
+{
+	return container_of(panel, struct db7430, panel);
+}
+
+static int db7430_power_on(struct db7430 *db)
+{
+	struct mipi_dbi *dbi = &db->dbi;
+	int ret;
+
+	/* Power up */
+	ret = regulator_bulk_enable(ARRAY_SIZE(db->regulators),
+				    db->regulators);
+	if (ret) {
+		dev_err(db->dev, "failed to enable regulators: %d\n", ret);
+		return ret;
+	}
+	msleep(50);
+
+	/* Assert reset >=1 ms */
+	gpiod_set_value_cansleep(db->reset, 1);
+	usleep_range(1000, 5000);
+	/* De-assert reset */
+	gpiod_set_value_cansleep(db->reset, 0);
+	/* Wait >= 10 ms */
+	msleep(10);
+	dev_dbg(db->dev, "de-asserted RESET\n");
+
+	/*
+	 * This is set to 0x0a (RGB/BGR order + horizontal flip) in order
+	 * to make the display behave normally. If this is not set the displays
+	 * normal output behaviour is horizontally flipped and BGR ordered. Do
+	 * it twice because the first message doesn't always "take".
+	 */
+	mipi_dbi_command(dbi, MIPI_DCS_SET_ADDRESS_MODE, 0x0a);
+	mipi_dbi_command(dbi, MIPI_DCS_SET_ADDRESS_MODE, 0x0a);
+	mipi_dbi_command(dbi, DB7430_ACCESS_PROT_OFF, 0x00);
+	mipi_dbi_command(dbi, DB7430_PANEL_DRIVING, 0x28, 0x08);
+	mipi_dbi_command(dbi, DB7430_SOURCE_CONTROL,
+			 0x01, 0x30, 0x15, 0x05, 0x22);
+	mipi_dbi_command(dbi, DB7430_GATE_INTERFACE,
+			 0x10, 0x01, 0x00);
+	mipi_dbi_command(dbi, DB7430_DISPLAY_H_TIMING,
+			 0x06, 0x55, 0x03, 0x07, 0x0b,
+			 0x33, 0x00, 0x01, 0x03);
+	/*
+	 * 0x00 in datasheet 0x01 in vendor code 0x00, it seems 0x01 means
+	 * DE active high and 0x00 means DE active low.
+	 */
+	mipi_dbi_command(dbi, DB7430_RGB_SYNC_OPTION, 0x01);
+	mipi_dbi_command(dbi, DB7430_GAMMA_SET_RED,
+		/* R positive gamma */ 0x00,
+		0x0A, 0x31, 0x3B, 0x4E, 0x58, 0x59, 0x5B, 0x58, 0x5E, 0x62,
+		0x60, 0x61, 0x5E, 0x62, 0x55, 0x55, 0x7F, 0x08,
+		/* R negative gamma */ 0x00,
+		0x0A, 0x31, 0x3B, 0x4E, 0x58, 0x59, 0x5B, 0x58, 0x5E, 0x62,
+		0x60, 0x61, 0x5E, 0x62, 0x55, 0x55, 0x7F, 0x08);
+	mipi_dbi_command(dbi, DB7430_GAMMA_SET_GREEN,
+		/* G positive gamma */ 0x00,
+		0x25, 0x15, 0x28, 0x3D, 0x4A, 0x48, 0x4C, 0x4A, 0x52, 0x59,
+		0x59, 0x5B, 0x56, 0x60, 0x5D, 0x55, 0x7F, 0x0A,
+		/* G negative gamma */ 0x00,
+		0x25, 0x15, 0x28, 0x3D, 0x4A, 0x48, 0x4C, 0x4A, 0x52, 0x59,
+		0x59, 0x5B, 0x56, 0x60, 0x5D, 0x55, 0x7F, 0x0A);
+	mipi_dbi_command(dbi, DB7430_GAMMA_SET_BLUE,
+		/* B positive gamma */ 0x00,
+		0x48, 0x10, 0x1F, 0x2F, 0x35, 0x38, 0x3D, 0x3C, 0x45, 0x4D,
+		0x4E, 0x52, 0x51, 0x60, 0x7F, 0x7E, 0x7F, 0x0C,
+		/* B negative gamma */ 0x00,
+		0x48, 0x10, 0x1F, 0x2F, 0x35, 0x38, 0x3D, 0x3C, 0x45, 0x4D,
+		0x4E, 0x52, 0x51, 0x60, 0x7F, 0x7E, 0x7F, 0x0C);
+	mipi_dbi_command(dbi, DB7430_BIAS_CURRENT_CTRL, 0x33, 0x13);
+	mipi_dbi_command(dbi, DB7430_DDV_CTRL, 0x11, 0x00, 0x00);
+	mipi_dbi_command(dbi, DB7430_GAMMA_CTRL_REF, 0x50, 0x50);
+	mipi_dbi_command(dbi, DB7430_DCDC_CTRL, 0x2f, 0x11, 0x1e, 0x46);
+	mipi_dbi_command(dbi, DB7430_VCL_CTRL, 0x11, 0x0a);
+
+	return 0;
+}
+
+static int db7430_power_off(struct db7430 *db)
+{
+	/* Go into RESET and disable regulators */
+	gpiod_set_value_cansleep(db->reset, 1);
+	return regulator_bulk_disable(ARRAY_SIZE(db->regulators),
+				      db->regulators);
+}
+
+static int db7430_unprepare(struct drm_panel *panel)
+{
+	return db7430_power_off(to_db7430(panel));
+}
+
+static int db7430_disable(struct drm_panel *panel)
+{
+	struct db7430 *db = to_db7430(panel);
+	struct mipi_dbi *dbi = &db->dbi;
+
+	mipi_dbi_command(dbi, MIPI_DCS_SET_DISPLAY_OFF);
+	msleep(25);
+	mipi_dbi_command(dbi, MIPI_DCS_ENTER_SLEEP_MODE);
+	msleep(120);
+
+	return 0;
+}
+
+static int db7430_prepare(struct drm_panel *panel)
+{
+	return db7430_power_on(to_db7430(panel));
+}
+
+static int db7430_enable(struct drm_panel *panel)
+{
+	struct db7430 *db = to_db7430(panel);
+	struct mipi_dbi *dbi = &db->dbi;
+
+	/* Exit sleep mode */
+	mipi_dbi_command(dbi, MIPI_DCS_EXIT_SLEEP_MODE);
+	msleep(20);
+
+	/* NVM (non-volatile memory) load sequence */
+	mipi_dbi_command(dbi, DB7430_UNKNOWN_D4, 0x52, 0x5e);
+	mipi_dbi_command(dbi, DB7430_UNKNOWN_F8, 0x01, 0xf5, 0xf2, 0x71, 0x44);
+	mipi_dbi_command(dbi, DB7430_UNKNOWN_FC, 0x00, 0x08);
+	msleep(150);
+
+	/* CABC turn on sequence (BC = backlight control) */
+	mipi_dbi_command(dbi, DB7430_UNKNOWN_B4, 0x0f, 0x00, 0x50);
+	mipi_dbi_command(dbi, DB7430_USER_SELECT, 0x80);
+	mipi_dbi_command(dbi, DB7430_UNKNOWN_B7, 0x24);
+	mipi_dbi_command(dbi, DB7430_UNKNOWN_B8, 0x01);
+
+	/* Turn on display */
+	mipi_dbi_command(dbi, MIPI_DCS_SET_DISPLAY_ON);
+
+	return 0;
+}
+
+/**
+ * db7430_get_modes() - return the mode
+ * @panel: the panel to get the mode for
+ * @connector: reference to the central DRM connector control structure
+ */
+static int db7430_get_modes(struct drm_panel *panel,
+			    struct drm_connector *connector)
+{
+	struct db7430 *db = to_db7430(panel);
+	struct drm_display_mode *mode;
+	static const u32 bus_format = MEDIA_BUS_FMT_RGB888_1X24;
+
+	mode = drm_mode_duplicate(connector->dev, &db7430_480_800_mode);
+	if (!mode) {
+		dev_err(db->dev, "failed to add mode\n");
+		return -ENOMEM;
+	}
+
+	connector->display_info.bpc = 8;
+	connector->display_info.width_mm = mode->width_mm;
+	connector->display_info.height_mm = mode->height_mm;
+	connector->display_info.bus_flags =
+		DRM_BUS_FLAG_PIXDATA_DRIVE_NEGEDGE;
+	drm_display_info_set_bus_formats(&connector->display_info,
+					 &bus_format, 1);
+
+	drm_mode_set_name(mode);
+	mode->type = DRM_MODE_TYPE_DRIVER | DRM_MODE_TYPE_PREFERRED;
+
+	drm_mode_probed_add(connector, mode);
+
+	return 1;
+}
+
+static const struct drm_panel_funcs db7430_drm_funcs = {
+	.disable = db7430_disable,
+	.unprepare = db7430_unprepare,
+	.prepare = db7430_prepare,
+	.enable = db7430_enable,
+	.get_modes = db7430_get_modes,
+};
+
+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");
+	}
+
+	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;
+}
+
+static int db7430_remove(struct spi_device *spi)
+{
+	struct db7430 *db = spi_get_drvdata(spi);
+
+	drm_panel_remove(&db->panel);
+	return 0;
+}
+
+/*
+ * The DB7430 display controller may be used in several display products,
+ * so list the different variants here and add per-variant data if needed.
+ */
+static const struct of_device_id db7430_match[] = {
+	{ .compatible = "samsung,lms397kf04", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, db7430_match);
+
+static struct spi_driver db7430_driver = {
+	.probe		= db7430_probe,
+	.remove		= db7430_remove,
+	.driver		= {
+		.name	= "db7430-panel",
+		.of_match_table = db7430_match,
+	},
+};
+module_spi_driver(db7430_driver);
+
+MODULE_AUTHOR("Linus Walleij <linus.walleij@linaro.org>");
+MODULE_DESCRIPTION("Samsung DB7430 panel driver");
+MODULE_LICENSE("GPL v2");