A suggestion on LCD peripheral (IDFGH-7191)

[LucivorLin]

Is your feature request related to a problem? Please describe.

A clear and concise description of what the problem is. Ex. I'm always frustrated when I use LCD peripherals.
SPI master settings cannot be configured in function esp_lcd_new_panel_io_spi(), but I want to change TX to LSB first, to ensure the color of my LCD is correct.

Describe the solution you'd like

in /esp-idf/components/esp_lcd/src/sep_lcd_panel_io_spi.c,

spi_device_interface_config_t devcfg = {
        .flags = SPI_DEVICE_HALFDUPLEX,

The flag can be set as a parameter to ensure the flexibility of the SPI master device driving the screen.

Describe alternatives you've considered

Give some extra functions of API to change these settings.

Chinese

LCD外设生成的SPI主设备难以更改flag参数，但有屏幕修改LSB/MSB等一些需求。

[Alvin1Zhang]

Thanks for reporting.

[suda-morris]

@LucivorLin Yes, we didn't expose all the underlying spi device flags to LCD IO layer by design (because not all spi flags are suitable for LCD). But left the space to extend them in the future by adding more flags into esp_lcd_panel_io_spi_config_t.flags.
Which flag in your case want to have? SPI_DEVICE_TXBIT_LSBFIRST or SPI_DEVICE_RXBIT_LSBFIRST or SPI_DEVICE_BIT_LSBFIRST?

[LucivorLin]

@suda-morris SPI_DEVICE_TXBIT_LSBFIRST is I want.

[suda-morris]

@LucivorLin
spi-lcd-support-transmit-lsb-first.patch.zip

Is this patch sufficient for you? Sorry I don't have an LCD at hand that acquires an LSB first transmission.

Ways to apply the patch:

1. decompress the zip file, and get the .patch file (e.g. my_fix.patch)
2. cd $IDF_PATH , check out the master branch
3. git apply my_fix.patch or git am my_fix.patch

[LucivorLin]

After apply the patch, what should I do?
Since the flags of esp_lcd_new_panel_io_spi didn't change, I would like to ensure my operation is correct.

xxx@LAPTOP-XXXXXXXX MINGW64 /e/Softwares/ESP/Container/esp-idf (master)
$ git apply temp/spi-lcd-support-transmit-lsb-first.patch
error: can't open patch 'temp/spi-lcd-support-transmit-lsb-first.patch': Permission denied

xxx@LAPTOP-XXXXXXXX MINGW64 /e/Softwares/ESP/Container/esp-idf (master)
$ git am temp/spi-lcd-support-transmit-lsb-first.patch

xxx@LAPTOP-XXXXXXXX MINGW64 /e/Softwares/ESP/Container/esp-idf (master)

Should there be any reaction of the latter command line? @suda-morris

[suda-morris]

@LucivorLin The patch file extracted from the attached zip file is 0001-lcd-spi-lcd-support-transmit-lsb-first.patch. Maybe you didn't decompress it successfully?

[LucivorLin]

Now I successfully applied, and I added .flags.lsb_first = 1 in esp_lcd_panel_io_spi_config_t io_config.
However, since I am new to ESP-IDF master branch, I cannot build the project as before, the error shows as follow:

Traceback (most recent call last):
  File "E:/Softwares/ESP/Container/esp-idf/tools/ldgen/ldgen.py", line 16, in <module>
    from ldgen.entity import EntityDB
  File "E:\Softwares\ESP\Container\esp-idf\tools\ldgen\ldgen\entity.py", line 12, in <module>
    from pyparsing import (Group, Literal, OneOrMore, ParseException, SkipTo, Suppress, White, Word, ZeroOrMore, alphas,
ImportError: cannot import name 'rest_of_line' from 'pyparsing' (e:\Softwares\ESP\Tools\python_env\idf4.4_py3.8_env\lib\site-packages\pyparsing.py)
[2/8] Performing build step for 'bootloader'
[1/1] cmd.exe /C "cd /D E:\ESP32_Projects\S2_projects\lvgl\build\bootloader\esp-idf\esptool_py && e:\Softwares\ESP\Tools\python_env\idf4.4_py3.8_env\Scripts\python.exe E:/Softwares/ESP/Container/esp-idf/components/partition_table/check_sizes.py --offset 0x8000 bootloader 0x1000 E:/ESP32_Projects/S2_projects/lvgl/build/bootloader/bootloader.bin"
Bootloader binary size 0x5100 bytes. 0x1f00 bytes (28%) free.
ninja: build stopped: subcommand failed.
ninja failed with exit code 1

@suda-morris

[suda-morris]

the pyparsing dependency of ldgen has been upgraded on master branch. I guess you need to rerun the "install.sh" script to install the python environment needed for master branch. Currently you're using the idf 4.4 environment for compiling the master branch (e:\Softwares\ESP\Tools\python_env\idf4.4_py3.8_env)

Alternatively, I guess this patch can also be applied to 4.4 release branch. 🤔

[LucivorLin]

Well, I tried using the patch in v4.4.
However, the LCD cannot work, I think it may be because of the priority of the operator in C language.
Is that better to change the code from

spi_device_interface_config_t devcfg = {
        .flags = SPI_DEVICE_HALFDUPLEX | io_config->flags.lsb_first ? SPI_DEVICE_TXBIT_LSBFIRST : 0,

to

spi_device_interface_config_t devcfg = {
        .flags = SPI_DEVICE_HALFDUPLEX | (io_config->flags.lsb_first ? SPI_DEVICE_TXBIT_LSBFIRST : 0),

?
@suda-morris

[suda-morris]

@LucivorLin Ah yes, my bad. Nice found. So with your fix, does that work now?

[LucivorLin]

It works properly now.