On 19-05-23, 13:00, Stephan Gerhold wrote: > The bam_dma driver needs to know the number of channels and execution > environments (EEs) at probe time. If we are in full control of the BAM > controller this information can be obtained from the BAM identification > registers (BAM_REVISION/BAM_NUM_PIPES). > > When the BAM is "controlled remotely" it is more complicated. The BAM > might not be on at probe time, so reading the registers could fail. > This is why the information must be added to the device tree in this > case, using "num-channels" and "qcom,num-ees". > > However, there are also some BAM instances that are initialized by > something else but we still have a clock that allows to turn it on when > needed. This can be set up in the DT with "qcom,controlled-remotely" > and "clocks" and is already supported by the bam_dma driver. Examples > for this are the typical BLSP BAM instances on older SoCs, QPIC BAM > (for NAND) and the crypto BAM on some SoCs. > > In this case, there is no need to read "num-channels" and > "qcom,num-ees" from the DT. The BAN can be turned on using the clock > so we can just read it from the BAM registers like in the normal case. > > Check for the BAM clock earlier and skip reading "num-channels" and > "qcom,num-ees" if it is present to allow simplifying the DT description > a bit. Applied, thanks -- ~Vinod
