IMX7 Yocto Device Tree Setup for PH320480T009-LAC03 LCD with ILI9486 Driver

Hello, I am trying to launch thePH320480T009-LAC03
tft with an IMX7 that uses an Yocto image. The driver that uses the tft
is ST7769S, however the kernel of yocto does not provide this driver, therefore
I am using the ili9486 that has a very similar operation. To configure this
driver I have made the following configuration of the device tree to put the
SPI 4-Line interface(First I have removed the previous configuration of mxcfb1
from the device tree):

&PICO_PI_ECSPI4 {

                status = "okay";

                spidev@1 {

compatible =
"rohm,dh2228fv";

spi-max-frequency =
<60000000>;

reg = <1>;

status = "disabled";

};

mxcfb1:
fb@0 {

compatible = "ilitek,ili9486";

reg = <0>;

 

spi-max-frequency = <5000000>;

rotate = <0>;

buswidth = <8>;

regwidth = <16>;

reset-gpios = <&gpio 25
0>;

dc-gpios
= <&gpio 24 0>;

debug = <0>;

init = <0x20000ff

                0x1000001

                                               0x20000ff

0x1000011

                0x20000ff

                0x10000f0
0xc3

                0x10000f0
0x96

                0x1000036
0x40

                0x10000b4
0x01

                0x10000b6 0x20 0x02 0x3b

                0x10000e8 0x40 0x8a 0x00 0x00
0x29 0x19 0xa5 0x33

                                               0x10000c1
0x0x06

0x10000c2
0xa7

0x10000c5
0x18

                0x10000e0 0x0f 0x09 0x0b 0x06
0x04 0x15 0x2f 0x54 0x42 0x3c 0x17 0x14 0x18 0x1b

                0x10000e1 0x0f 0x09 0x0b 0x06
0x04 0x03 0x2d 0x43 0x42 0x3b 0x16 0x14 0x17 0x1b

                0x10000f0 0xc3

                0x10000f0
0x96

                0x20000ff

                0x1000029>

};

};

The initial sequence is the recommended by the
manufacturer of the tft. When I start the program, I see that the screen
responds to the commands I am indicating in the initial sequence, since when
the last command of that sequence is displayed (display on), the display turns
on and shows many colored dots. And
this is all that the screen does, when I indicate that I upload an image (I
launch a program generated with the qt creator), it does not work, it still
shows the colored dots. I have measured the signal that comes out of the
SPI with an oscilloscope, and the signals it generates seem correct.

What could be the problem?

My theory is that the "b6h" command
that is launched in the initial sequence activates a bit (RM) that is to select
the RGB interface, therefore when I load an image by the SPI interface the screen
ignores it, since the wait that the signal arrives for another data bus.

How would I have to configure the initial
sequence to load the image by the SPI?

How would I have to configure the
device tree so that it would also generate an RGB interface?

 

 

thanks!

Can you describe what you have done so far to troubleshoot this? I imagine that you have gone into other distributions to see if you can find a similar driver?  Yes, basic questions, but perhaps gives an initial place to start the debugging.  Also do you have anything that annotates the initialization sequence (something to give an idea of what the initialization code is actually setting)?

Adam

You may want to make sure that your code is sending the proper
initialization sequence and that it sends the proper commands to upload the
image. One way to do this is with an oscilloscope that can perform serial
protocol analysis. The Rohde & Schwarz RTC1000, for example, is one such
scope. Although this isn't especially useful in this particular application,
the scope also I2C, CAN, and LIN serial interfaces in addition to SPI.