Waveshare/Adafruit E-ink Linux framebuffer out-of-tree module(s).
The familiy of drivers currently supports the following of Waveshare's e-ink panels:
2.13"
Currently, full support is only for the monochrome V3 model of Waveshare's panel. This is the fastest full updating device in the size of panel. Update times are within 2-ish seconds for a full update of the panel. Fast or partial update as they describe it in the documentation is in progress but is not complete/functional.
The main purpose of this driver is to provide a usable and consistent/common abstraction for using these displays under Linux. There currently are three differing versions of the codebase in C or Python for the three outstanding models of the product offerings from Dalian Good-Display (The ultimate manufacturer of these displays from Waveshare, Adafruit, etc.) with code that wasn't written to compensate for little more than differing timings on inits, resets, waits, etc. It's a bit of a mess and this project seeks to sort some or all of this out, largely transparently to your code, with a device tree overlay to select out your desired panel to work with and basically do a fire and forget type operation on a stock Linux framebuffer device. We handle the rest for you.
The following is an example of the Device Tree entry for the current driver with the supported panel on a Raspberry PI type device:
// Waveshare Eink as frame buffer
#include <dt-bindings/gpio/gpio.h>
/dts-v1/;
/plugin/;
/ {
compatible = "brcm,bcm2835";
fragment@0 {
target = <&spidev0>;
__overlay__ {
status = "disabled";
};
};
fragment@1 {
target = <&spidev1>;
__overlay__ {
status = "disabled";
};
};
fragment@2 {
target = <&gpio>;
__overlay__ {
wseinkfb_pins: wseinkfb_pins {
brcm,pins = <17 24 25>;
brcm,function = <1>; /* out */
};
};
};
fragment@2 {
target = <&spi0>;
__overlay__ {
/* needed to avoid dtc warning */
#address-cells = <1>;
#size-cells = <0>;
status = "okay";
wseinkfb@0 {
compatible = "waveshare,213";
reg = <0>; /* CE0 */
pinctrl-names = "default";
pinctrl-0 = <&wseinkfb_pins>;
spi-max-frequency = <12500000>;
ws,rst-gpios = <&gpio 17 GPIO_ACTIVE_LOW>;
ws,dc-gpios = <&gpio 25 GPIO_ACTIVE_HIGH>;
ws,busy-gpios = <&gpio 24 GPIO_ACTIVE_LOW>;
status = "okay";
};
};
};
};
So this should give you an idea about bindings. Compatible lines equate to "waveshare," where is the inches and decimal value of the display size, with the decimal removed. The rest is pretty self-explanatory to someone skilled in the art.
This too, is pretty straightforward. Like any other out-of-tree kernel build.
In order for it to work right, though, you will need the following added to your kernel config, either as a defconfig for your target or as a Yocto kernel config fragment:
CONFIG_FB=y
CONFIG_SPI=y
CONFIG_FB_SYS_FOPS=y
CONFIG_FB_CFB_FILLRECT=y
CONFIG_FB_CFB_COPYAREA=y
CONFIG_FB_CFB_IMAGEBLIT=y
CONFIG_FB_CFB_REV_PIXELS_IN_BYTE=y
CONFIG_FB_DEFERRED_IO=y
- Prior versions/models of the panels aren't going to be realistically supported. The chips themselves will provide support for a wider range than I can support. If you can hand me a panel to work with that's an older version (For example, the V2 2.13 inch panel needs a custom LUT setup, whereas the OTP programmed V3 appears to not need one based on a review of the "library" Waveshare provides...) so I can get LUTs, etc. worked in, we're good to go and I can support.
- Adding the other displays in Waveshare's lineup. This will entail more driver modules unless it matches up with a current driver IC. There's quite a few differences between the panels, so there's
- Multicolor. Most of the lineup for the chipsets from Solomon that're being used here are capable of tricolor and more. The drawback being that the color electrophoretic changes are...much more time consuming for an update in many cases.