The difficulty in determining a starting point is due to the manufacturers drawings. They do not provide any clarity as to how they’ve implemented the ILI9327 interface. I’ll try to explain...
Refer to the Ilitek datasheet, page 8. At the top of that page, you’ll see an entry for the controller mode bits IM[0:2]. The logic levels applied to those three points determine how to talk to the controller. Set all three bits to a logic high and you have an 8 bit SPI (serial) interface. Set them all low and you have a parallel, 6 bits per color interface.
Under most circumstances, in the high volume world of small LCDs, these bits are set to the end customers desired interface type by the LCD panel manufacturer. The customer has a specific application for the panel and they know the interface type they want so the bits are controlled by the routing of the copper traces on the flexible pc link between the ILI9327 and the customer interface points. LCD manufacturer gives their customer exactly what they want for their application.
If the panel has been designed and built as a general purpose device, those three bits should be controllable by the end customer. This would typically be done by bringing those three signals out to copper pads in a way that you can connect each signal to logic high or low by soldering a bridge between pads.
What I cannot determine from the drawings is what Topfoison has done with those three pins from the ILI9327. I also see that they’ve changed some signal names from those used in ILI9327 datasheet, making it even harder to figure out what you have, interface wise. For example, there should be a signal named DCX which controls a write to the device and it determines if that write is data or a control word. The process of elimination doesn’t work because they show pins used by both the serial and parallel methods.
I think you have two choices. If you’re a hardware savvy kind of person, get out the microscope/magnifier and start tracing pins and looking for solder pads to figure out what mode you have. If that does not sound plausible, contact Topfoison and hope someone there speaks decent English, unless of course you speak Mandarin.
As a last resort, if you can post a decent, high resolution picture of the flex circuit, we might be able to identify things for you. That’s a bit of a long shot but it’s certainly an option.