On Tue, Mar 12, 2024 at 05:32:52PM +0000, Abdellatif El Khlifi wrote: > Hi Mathieu, > > On Tue, Mar 12, 2024 at 10:29:52AM -0600, Mathieu Poirier wrote: > > > This is an initial patchset for allowing to turn on and off the remote processor. > > > The FW is already loaded before the Corstone-1000 SoC is powered on and this > > > is done through the FPGA board bootloader in case of the FPGA target. Or by the Corstone-1000 FVP model > > > (emulator). > > > > > >From the above I take it that booting with a preloaded firmware is a > > scenario that needs to be supported and not just a temporary stage. > > The current status of the Corstone-1000 SoC requires that there is > a preloaded firmware for the external core. Preloading is done externally > either through the FPGA bootloader or the emulator (FVP) before powering > on the SoC. > Ok > Corstone-1000 will be upgraded in a way that the A core running Linux is able > to share memory with the remote core and also being able to access the remote > core memory so Linux can copy the firmware to. This HW changes are still > This is why this patchset is relying on a preloaded firmware. And it's the step 1 > of adding remoteproc support for Corstone. > Ok, so there is a HW problem where A core and M core can't see each other's memory, preventing the A core from copying the firmware image to the proper location. When the HW is fixed, will there be a need to support scenarios where the firmware image has been preloaded into memory? > When the HW is ready, we will be able to avoid preloading the firmware > and the user can do the following: > > 1) Use a default firmware filename stated in the DT (firmware-name property), > that's the one remoteproc subsystem will use initially, load the firmware file > and start the remote core. > > 2) Then, the user can choose to use another firmware file: > > echo stop >/sys/class/remoteproc/remoteproc0/state > echo -n new_firmware.elf > /sys/class/remoteproc/remoteproc0/firmware > echo start >/sys/class/remoteproc/remoteproc0/state > > > > The plan for the driver is as follows: > > > > > > Step 1: provide a foundation driver capable of turning the core on/off > > > > > > Step 2: provide mailbox support for comms > > > > > > Step 3: provide FW reload capability > > > > > What happens when a user wants to boot the remote processor with the > > firmware provided on the file system rather than the one preloaded > > into memory? > > We will support this scenario when the HW is upgraded and copying the firmware > to the remote core memory becomes possible. > > > Furthermore, how do we account for scenarios where the > > remote processor goes from running a firmware image on the file system > > to the firmware image loaded by an external entity? Is this a valid > > scenario? > > No, this scenario won't apply when we get the HW upgrade. No need for an > external entity anymore. The firmware(s) will all be files in the linux filesystem. > > > > Steps 2 & 3 are waiting for a HW update so the Cortex-A35 (running Linux) can share memory with > > > the remote core. > > > > > > I'm happy to provide more explanation in the commit log to reflect this status. > > > > > > Is it OK that we go with step 1 as a foundation please ? > > > > > > > First let's clarify all the scenarios that need to be supported. From > > there I will advise on how to proceed and what modifications to the > > subsystem's core should be made, if need be. > > Thanks, I hope the answers above provide the information needed. > > Cheers > Abdellatif
