On Tue, May 07, 2024 at 11:57:26AM +0200, Noralf Trønnes wrote: > The MIPI DBI 2.0 specification (2005) lists only two pixel formats for > the Type C Interface (SPI) and that is 3-bits/pixel RGB111 with > 2 options for bit layout. > > For Type A and B (parallel) the following formats are listed: RGB332, > RGB444, RGB565, RGB666 and RGB888 (some have 2 options for the bit layout). > > Many MIPI DBI compatible controllers support all interface types on the > same chip and often the manufacturers have chosen to provide support for > the Type A/B interface pixel formats also on the Type C interface. > > Some chips provide many pixel formats with optional bit layouts over SPI, > but the most common by far are RGB565 and RGB666. So even if the > specification doesn't list these formats for the Type C interface, the > industry has chosen to include them. > > The MIPI DCS specification lists the standard commands that can be sent > over the MIPI DBI interface. The set_address_mode (36h) command has one > bit in the parameter that controls RGB/BGR order: > This bit controls the RGB data latching order transferred from the > peripheral’s frame memory to the display device. > This means that each supported RGB format also has a BGR variant. > > Based on this rationale document the following pixel formats describing > the bit layout going over the wire: > - RGB111 (option 1): x2r1g1b1r1g1b1 (2 pixels per byte) > - BGR111 (option 1): x2b1g1r1b1g1r1 (2 pixels per byte) > - RGB111 (option 2): x1r1g1b1x1r1g1b1 (2 pixels per byte) > - BGR111 (option 2): x1b1g1r1x1b1g1r1 (2 pixels per byte) > - RGB565: r5g6b5 (2 bytes) > - BGR565: b5g6r5 (2 bytes) > - RGB666: r6x2g6x2b6x2 (3 bytes) > - BGR666: b6x2g6x2r6x2 (3 bytes) > (x: don't care) > > Signed-off-by: Noralf Trønnes <noralf@xxxxxxxxxxx> > --- > .../bindings/display/panel/panel-mipi-dbi-spi.yaml | 31 ++++++++++++++++++++++ > 1 file changed, 31 insertions(+) > > diff --git a/Documentation/devicetree/bindings/display/panel/panel-mipi-dbi-spi.yaml b/Documentation/devicetree/bindings/display/panel/panel-mipi-dbi-spi.yaml > index e808215cb39e..dac8f9af100e 100644 > --- a/Documentation/devicetree/bindings/display/panel/panel-mipi-dbi-spi.yaml > +++ b/Documentation/devicetree/bindings/display/panel/panel-mipi-dbi-spi.yaml > @@ -50,6 +50,12 @@ description: | > | Command or data | > |<D7><D6><D5><D4><D3><D2><D1><D0>| > > + The standard defines one pixel format for type C: RGB111. The industry > + however has decided to provide the type A/B interface pixel formats also on > + the Type C interface and most common among these are RGB565 and RGB666. > + The MIPI DCS command set_address_mode (36h) has one bit that controls RGB/BGR > + order. This gives each supported RGB format a BGR variant. > + > The panel resolution is specified using the panel-timing node properties > hactive (width) and vactive (height). The other mandatory panel-timing > properties should be set to zero except clock-frequency which can be > @@ -90,6 +96,29 @@ properties: > > spi-3wire: true > > + format: > + description: > > + Pixel format in bit order as going on the wire: > + * `x2r1g1b1r1g1b1` - RGB111, 2 pixels per byte > + * `x2b1g1r1b1g1r1` - BGR111, 2 pixels per byte > + * `x1r1g1b1x1r1g1b1` - RGB111, 2 pixels per byte > + * `x1b1g1r1x1b1g1r1` - BGR111, 2 pixels per byte > + * `r5g6b5` - RGB565, 2 bytes > + * `b5g6r5` - BGR565, 2 bytes > + * `r6x2g6x2b6x2` - RGB666, 3 bytes > + * `b6x2g6x2r6x2` - BGR666, 3 bytes > + This property is optional for backwards compatibility and `r5g6b5` is > + assumed in its absence. Use schemas, not free form text: default: r5g6b5 > + enum: > + - x2r1g1b1r1g1b1 > + - x2b1g1r1b1g1r1 > + - x1r1g1b1x1r1g1b1 > + - x1b1g1r1x1b1g1r1 > + - r5g6b5 > + - b5g6r5 > + - r6x2g6x2b6x2 > + - b6x2g6x2r6x2 > + > required: > - compatible > - reg > @@ -116,6 +145,8 @@ examples: > reset-gpios = <&gpio 25 GPIO_ACTIVE_HIGH>; > write-only; > > + format = "r5g6b5"; > + > backlight = <&backlight>; > > width-mm = <35>; > > -- > 2.45.0 >
