bsp: Proposal of LCD API

[tore-espressif]

This PR allows LCD initialization without LVGL. The API is in a separate file bsp/lcd.h to indicate that it is not needed in usual usacases.

I'd like to discuss few issues before I implement it for all BSPs:

1. Is it OK (at least for now) to omit the deinit functions? EDIT: Seems to be OK for now
2. Should we extend the backlight_init function with variable LEDC channels and timers? (the user can, after all, implement his own backlight control)

Any ideas welcome!

Related #121

[espzav]

@tore-espressif Thank you! Great work! Some comments left.

[tore-espressif]

@espzav Changes compared to the initial proposal:

• Backlight is now initialized (but not turned on)
• Display is reset and initialized (but not turned on)
• new_display function does not need any parameter
• removed esp_timer dependency from BSPs (probably a leftover before we moved to esp_lvgl_port
• Add backlight control to Korvo 2 BSP

TODOs:

• Check backlight function on Korvo 2
• Use same draw_buffer_size macros across BSPs EDIT: Let's do this later so the MR does not get too big

[tore-espressif]

@TTauriainenQt PTAL!

[TT-Qt]

Hi @tore-espressif,

I did not find a way to set callback function for on_color_trans_done with this API proposal. Is that supported here somehow?

[espzav]

Hi @TTauriainenQt,
here is the example of usage:

static bool _flush_ready_callback(esp_lcd_panel_io_handle_t panel_io, esp_lcd_panel_io_event_data_t *edata, void *user_ctx)
{
    ....
    return false;
}

...

esp_lcd_panel_handle_t lcd_panel;
esp_lcd_panel_io_handle_t lcd_io;
err = bsp_display_new(&lcd_panel, &lcd_io);

/* Register done callback */
const esp_lcd_panel_io_callbacks_t cbs = {
    .on_color_trans_done = _flush_ready_callback,
};
esp_lcd_panel_io_register_event_callbacks(lcd_io, &cbs, NULL);

...

[TT-Qt]

Ok, thank you! Pull request looks good to me.

[espzav]

@tore-espressif Thank you for this PR! Great work! Thank you for fix some minor issues in other BSPs. Some notes:

1. Same as LCD should be new function for touch init. Do you plan it in next PR?
2. The EV board is missing the bsp_display_new function.
3. Did you test all on hardware?

Thanks!

[tore-espressif]

@tore-espressif Thank you for this PR! Great work! Thank you for fix some minor issues in other BSPs. Some notes:

1. Same as LCD should be new function for touch init. Do you plan it in next PR?
2. The EV board is missing the bsp_display_new function.
3. Did you test all on hardware?

Thanks!

@espzav Thank you very much for the review!

1. Touch will be done it another PR, so this one isn't too big
2. I'll leave the EV board for follow-up MR, I don't understand the RGB driver enough, yet
3. Tested on Korvo-2, Kaluga, Wrover and USB-OTG. All work OK!