The right way to check SPI DMA completion

[rickyzhang]

That's a good point. I think you say min SCL write cycle is 100ns. That max out clock rate at 10Mhz.

In fact, I'm doing interlacing in LCD driver. Thus, it only use half bandwidth from what I showed:

320 (width) x 240 (height) x 2 x 8 (bit) x 24 (fps) / 2 (interlacing) = 14.5 Mbps.

I will give a try like 20Mhz in SCL. But since Odroid-go may share SPI bus with SD card, I will look it deeper what is the impact.

I believe I can lower data traffic further by implementing delta update where only change between dual buffer is sent over SPI. But if I don't get it clear that DMA transmission is done upon the return of getting SPI trans call, I will still have the same issue.