Relations of SPI_DEV and SPI_HWCS


I use a bluepill and connected a SPI flash to it. So, I defined SPI_DEV(0) as SPI interface. I can see the data on my logic analyzer. This is fine. But when I use SPI_HWCS(0) as CS pin, I can’t see the pulse in my logic analyzer and the formating also fails. Therefore it is not the correct pin. When I change it to GPIO_PIN(PORT_A, 4), everything works fine. So my question: Is this a bug or do I understand something wrong?