i2c-designware: not possible to write to different i2c addresses in one transfer?

[Hans Verkuil <hverkuil+cisco@kernel.org>]

Hi,

I have this code in a driver (writing display EDID data into an EDID EEPROM):

        struct i2c_msg msg[] = {
                {
                        .addr = state->seg_client->addr,        // 0x30
                        .buf = &seg,
                        .len = 1,
                        .flags = 0,
                },
                {
                        .addr = state->data_client->addr,       // 0x50
                        .buf = data,
                        .len = len,
                        .flags = 0,
                },
        };

        err = i2c_transfer(state->dev_client->adapter, msg, ARRAY_SIZE(msg));

This worked fine for the Raspberry Pi 4B using the broadcom i2c driver, but for
the Raspberry Pi 5 using the designware driver it fails with -EINVAL and these
kernel messages:

[  272.284689] i2c_designware 1f00074000.i2c: i2c_dw_xfer_msg: invalid target address
[  272.305788] i2c_designware 1f00074000.i2c: controller active

Looking in i2c-designware-master.c it seems it cannot handle consecutive messages for
different addresses.

The i2c device I'm using is this one:

https://www.onsemi.com/pdf/datasheet/cat24c208-d.pdf

Is this a hardware limitation? Or is this a corner case that was never implemented?
Or just simply a bug?

Regards,

	Hans