Hi Finn, Op za 16 nov. 2019 om 04:36 schreef Finn Thain <fthain@xxxxxxxxxxxxxxxxxxx>: > > The zorro_esp driver uses both PIO and DMA transfers. If a failed DMA > transfer happened to be followed by a PIO transfer, the TCLOW and TCMED > registers would not get cleared. It is theoretically possible that the > stale value from the transfer counter or the TCLOW/TCMED registers > could then be used by the controller and the driver. Avoid that by > clearing these registers before each PIO transfer. Are you sure this is really needed? The only place where the driver reads these registers is after a data transfer. These are done using DMA on all Zorro boards, so I don’t think there’s a risk of stale values from a PIO transfer there. The only place the controller reads these registers is when a DMA command is issued. The only place where that is done is in the zorro_esp send_dma_command() functions. These all set both registers explicitly before issuing the DMA command to the controller, so I don’t think there’s a risk there either. Kind regards, Kars.
