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Date: Thu, 14 Mar 2024 08:52:59 -0600
From: Mathieu Poirier <mathieu.poirier@linaro.org>
To: Abdellatif El Khlifi <abdellatif.elkhlifi@arm.com>
Cc: Bjorn Andersson <andersson@kernel.org>,
	Rob Herring <robh+dt@kernel.org>, Liviu Dudau <liviu.dudau@arm.com>,
	Sudeep Holla <sudeep.holla@arm.com>,
	Lorenzo Pieralisi <lpieralisi@kernel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	Conor Dooley <conor+dt@kernel.org>, 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
Subject: Re: [PATCH 1/3] remoteproc: Add Arm remoteproc driver
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On Wed, Mar 13, 2024 at 05:17:56PM +0000, Abdellatif El Khlifi wrote:
> Hi Mathieu,
> 
> On Wed, Mar 13, 2024 at 10:25:32AM -0600, Mathieu Poirier wrote:
> > 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?
> 
> 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. 

Thanks,
Mathieu