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Tue, 26 Mar 2024 07:20:48 -0700 (PDT) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: <20240307194026.GA355455@e130802.arm.com> <20240311114442.GA82865@e130802.arm.com> <20240312173252.GA38992@e130802.arm.com> <20240313171756.GA82165@e130802.arm.com> <20240325171339.GA368569@e130802.arm.com> In-Reply-To: <20240325171339.GA368569@e130802.arm.com> From: Mathieu Poirier Date: Tue, 26 Mar 2024 08:20:37 -0600 Message-ID: Subject: Re: [PATCH 1/3] remoteproc: Add Arm remoteproc driver To: Abdellatif El Khlifi Cc: Sudeep Holla , Bjorn Andersson , Rob Herring , Liviu Dudau , Lorenzo Pieralisi , Krzysztof Kozlowski , Conor Dooley , Drew.Reed@arm.com, Adam.Johnston@arm.com, linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-remoteproc@vger.kernel.org Content-Type: text/plain; charset="UTF-8" On Mon, 25 Mar 2024 at 11:13, Abdellatif El Khlifi wrote: > > Hi Mathieu, > > > > > > > > > > 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? > > > > > > > > > > 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. > > > > > > > > > > > > > Very well. I am willing to continue with this driver but it does so little that > > > > I wonder if it wouldn't simply be better to move forward with upstreaming when > > > > the HW is fixed. The choice is yours. > > > > > > > > > > I think Robin has raised few points that need clarification. I think it was > > > done as part of DT binding patch. I share those concerns and I wanted to > > > reaching to the same concerns by starting the questions I asked on corstone > > > device tree changes. > > > > > > > I also agree with Robin's point of view. Proceeding with an initial > > driver with minimal functionality doesn't preclude having complete > > bindings. But that said and as I pointed out, it might be better to > > wait for the HW to be fixed before moving forward. > > We checked with the HW teams. The missing features will be implemented but > this will take time. > > The foundation driver as it is right now is still valuable for people wanting to > know how to power control Corstone external systems in a future proof manner > (even in the incomplete state). We prefer to address all the review comments > made so it can be merged. This includes making the DT binding as complete as > possible as you advised. Then, once the HW is ready, I'll implement the comms > and the FW reload part. Is that OK please ? > I'm in agreement with that plan as long as we agree the current preloaded heuristic is temporary and is not a valid long term scenario. > Cheers, > Abdellatif