I have problems with ethernet (using the HAL library 1.8.0) on the STM32F756ZG.
If I place the DMA buffers in the DTCM (0x20000000-0x2000ffff), it works fine. If I place the DMA buffer anywhere else (SRAM1, SRAM2), I get only on every second ping an answer (50% loss).
I don't use the MPU and I don't activate the data cache (SCB.CCR.DC = 0).
I also tried (despite the dcache being deactivated) flushing the data cache (SCB_DCacheClean()) before sending data in low_level_output() and invalidating the data cache (SCB_DCacheInvalidate()) before reading data in low_level_input(), but to no avail.
Does anybody has an idea?