Re: Device obligation to write into a DMA_FROM_DEVICE streaming DMA mapping

On 21/05/2019 18:14, Horia Geanta wrote: Hi, Is it mandatory for a device to write data in an area DMA mapped DMA_FROM_DEVICE? Can't the device just "ignore" that mapping - i.e. not write anything - and driver should expect original data to be found in that location (since it was not touched /

Device obligation to write into a DMA_FROM_DEVICE streaming DMA mapping

Hi, Is it mandatory for a device to write data in an area DMA mapped DMA_FROM_DEVICE? Can't the device just "ignore" that mapping - i.e. not write anything - and driver should expect original data to be found in that location (since it was not touched / written to by the device)? [Let's leave cac