If you have a boolean argument, rotation can be toggled.

    def rotated(self, rotated=True):
        self.write_cmd(SET_SEG_REMAP | (rotated & 1))
        self.write_cmd(SET_COM_OUT_DIR | ((rotated & 1) << 3))

Or if you want to be able to toggle either the segment or common ordering independently:

    def remap(self, seg=True, com=True):
        self.write_cmd(SET_SEG_REMAP | (seg & 1))
        self.write_cmd(SET_COM_OUT_DIR | ((com & 1) << 3))

Which will give you: rotate 0 deg, mirror-x, mirror-y and rotate 180 deg.

@mcauser I would then be in favour of adding separate mirror-x and mirror-y static methods as well. This would keep things easy and self-evident for the casual programmer.
seg, com, and even rotated are not very descriptive terms.
Remember, there are also kids learning with Micropython.

Hi @stroobandt
seg is short for Set Segment Re-map - 10.1.8 in the datasheet
com is short for Set COM Output Scan Direction - 10.1.14 in the datasheet
They can be used to control how the data written to the display driver is interpreted and shown.
Not the most novice friendly names, I agree. That's just what they are called in the datasheet.

There's a whole bunch more functionality this display supports which is not exposed in this driver.
Given this is a simple driver which is built into some ports, I'd go with a minimal implementation.
It's not obvious that mirror-x + mirror-y == rotate 180 deg either.

Changing the com output direction updates immediately on the display, but remapping the segments only affects new data that is written to the display, adding to novice confusion.

Perhaps it should be added to init_display() instead, as most, I'm assuming, would set the rotation once on init, then never rotate it at runtime. Same applies for setting the start address (for different size displays) and addressing mode (which has to match the framebuf mode).

@mcauser Dear Mike, I entirely agree with you that setting this during the initialisation of the display is the safest thing to do. However, the init_display() method belongs to the SSD1306 super class. In practice, this method is never directly used by the programmer.

I would rather propose adding a named upside_down=False parameter to the initialisation method of the following child classes:

class SSD1306_I2C(SSD1306):
     def __init__(self, width, height, i2c, addr=0x3c, external_vcc=False, upside_down=False):
         …

class SSD1306_SPI(SSD1306):
    def __init__(self, width, height, spi, dc, res, cs, external_vcc=False, upside_down=False):
        …

How do I proceed further?
Do I close this pull request and create a new one, or can I still change this one?

You could just add another commit, or update your existing commit with an --amend.
No need for a new PR. The PR is tied to your branch, so you can rewrite it as many times as you want and force push when you're done.

Display rotation was implemented in PR #7135

As mentioned above, rotation was implemented in 9eea51b and it looks like that is more general than the patch here. So closing.