Different data after the 1st transfer using SPI via DMA (using LL Libs)

[TheRaprus]

Hi everybody.

I'm facing a strange behaviour on my application. I'm using a STM 23H562, and I'm usign LL library to drive a SPI display (classic iLi).

I take the example from c:\Users\Massimo NUCLEO-H533RE\Examples_LL\SPI\*
and the display do what I want... only sometime!

Due to the 65535 max transfer length, I need to split it into 3 session. I wait the end of the previous as indicate in the example, using:

while (!LL_DMA_IsActiveFlag_TC(GPDMA2, LL_DMA_CHANNEL_0)){}
LL_DMA_ClearFlag_TC(GPDMA2, LL_DMA_CHANNEL_0);

But the color of the filling change (= the data transmitted to the display) from one session to the others. The 1st is correct, the second "sometime", the 3rd rarely.

But if I put a small delay from one session to the following everything work fine. 

How I can fix it?
It seems I must wait for some other flag, but donnow wich!

Moreover, the command to the display is based on a 8 bit spi data, so I change to 16 and back to 8 when I use the DMA. But the session of manual sending command to SPI after DMA fail because the TXC flag is always 0, it never change!

while (!LL_SPI_IsActiveFlag_TXC(SPI2)){}

Thank in advance.

[MOBEJ]

Hello @TheRaprus , 

Could you please specify which LCD you are using with SPI? Are you using a TFT LCD display module?

Thank you
Br

[TheRaprus]

I'm using a iLi9341 SPI display 320x240. It work only with SPI. With M4 DMA it work w/o problems.
SPI speed is 30MHz, but if I reduce there is no difference.

Because the total display memory is 320x240x2 byte = 153600B. I need 2 full DMA and one of ~22568B.

I tried to reduce the lengths to 60.000 and 20.000 but there is no differences.

What I presume is that the SPI shift reg isn't completely empty, so the 2nd or 3rd DMA Cycle had a dirty bit(s) in it, that "confuse" the display color command. 

Without DMA it work perfectly, changing the SPY from 8 to 16 bit, but I want the DMA, as in the M4 STM32!

The delay I mentioned above (between DMA calling) is 2 ms, 1 isn't enought.