Fix "OSError: [Errno 9] Bad file descriptor" for Waveshare EPDs

[motschel123]

Waveshare EPDs fully close the SPI file descriptor when being put to sleep.
This result in OSError: [Errno 9] Bad file descriptor when diplay_image is called a second time. See #452, #259.

It can be discussed whether this is a bug in the waveshare drivers or intended behavior. However the fix proposed in #259 has been an open PR (waveshareteam/e-Paper#406) for half a year now without any reactions, so it can be assumed to not get fixed.

So heres the fix for this implementation:
The epd_module.EPD() constructor has to be called again for each display_image step.
For this i implemented a small reinitialize_display function for the waveshare_display which recreates the epd_display each time display_image is called.
To safe resources I made the dynamic module import an Object field to be reusable.

I can confirm this code to work for the epd13in3k model and this model alone, as it's the only one I own.
But when looking into the waveshare epd drivers, the relevant piece of code is present for every model.

[Copilot]

Pull request overview

This PR aims to prevent OSError: [Errno 9] Bad file descriptor when updating Waveshare EPDs multiple times by reinitializing the EPD/SPI setup after the display is put to sleep (since some Waveshare drivers close the SPI FD during sleep()).

Changes:

• Persist the dynamically imported Waveshare EPD module on the WaveshareDisplay instance for reuse.
• Add a reinitialize_display() helper intended to recreate the EPD() instance and run its init method again.
• Document the rationale for reinitialization in-code.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.