1. Pass. Just watch out for accidentally dropping into the swiotlb paths should the DMA channel not be able to address the memory range required.
2. You can't specify a channel for HDMI audio, but you can disable it by altering /boot/firmware/config.txt with "dtoverlay=vc4-kms-v3d,noaudio"
3.You can't explicitly. You specify the DREQ, and the first available channel is assigned.
4. Some channels are used by the firmware.
5. https://github.com/raspberrypi/linux/co ... 6301c0eff6 On Pi4/CM4 there are 4 DMA channels that support 40bit addressing, whilst the rest only support 30bit addressing. They have to be represented as separate controllers because there is no other way to specify which capabilities you need.
2. You can't specify a channel for HDMI audio, but you can disable it by altering /boot/firmware/config.txt with "dtoverlay=vc4-kms-v3d,noaudio"
3.You can't explicitly. You specify the DREQ, and the first available channel is assigned.
4. Some channels are used by the firmware.
5. https://github.com/raspberrypi/linux/co ... 6301c0eff6 On Pi4/CM4 there are 4 DMA channels that support 40bit addressing, whilst the rest only support 30bit addressing. They have to be represented as separate controllers because there is no other way to specify which capabilities you need.
Statistics: Posted by 6by9 — Thu May 23, 2024 8:48 pm