Hi, Le mercredi 12 juin 2024 à 23:25 +0300, Laurent Pinchart a écrit : > On Wed, Jun 12, 2024 at 03:43:58PM -0400, Nicolas Dufresne wrote: > > Le mercredi 12 juin 2024 à 13:37 +0900, Tomasz Figa a écrit : > > > > Why is this flag needed ? Given that the usage model requires the V4L2 > > > > device to be a dma buf importer, why would userspace set the > > > > V4L2_BUF_CAP_SUPPORTS_RESTRICTED_MEM flag and pass a non-restricted > > > > buffer to the device ? > > > > > > Given that the flag is specified at REQBUF / CREATE_BUFS time, it's > > > actually useful to tell the driver the queue is operating in restricted > > > (aka secure) mode. > > > > > > I suppose we could handle that at the time of a first QBUF, but that > > > would make the driver initialization and validation quite a bit of pain. > > > So I'd say that the design being proposed here makes things simpler and > > > more clear, even if it doesn't add any extra functionality. > > > > There is few more reasons I notice in previous series (haven't read the latest): > > > > - The driver needs to communicate through the OPTEE rather then SCP and some > > communication are needed just to figure-out things like supported profile/level > > resolutions etc. > > - The driver needs to allocate auxiliary buffers in secure heap too, allocation > > at runtime are not the best > > Will the same driver support both modes on the same system ? Yes, as per this implementation, it seems you can flip from one mode to another even on the same instance. Nicolas > > > Note that the discussion around this flag already took place in the very first > > iteration of the serie, it was originally using a CID and that was a proposed > > replacement from Hans. >
