linux-kernel - Re: [PATCH 1/2] remoteproc: imx_dsp_rproc: add mandatory find_loaded_rsc

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Message-ID: <ZPZJLJpL+f9nB1cn@p14s>
Date:   Mon, 4 Sep 2023 15:16:28 -0600
From:   Mathieu Poirier <mathieu.poirier@...aro.org>
To:     Iuliana Prodan <iuliana.prodan@....com>
Cc:     "Iuliana Prodan (OSS)" <iuliana.prodan@....nxp.com>,
        Bjorn Andersson <andersson@...nel.org>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        "S.J. Wang" <shengjiu.wang@....com>,
        Fabio Estevam <festevam@...il.com>,
        Daniel Baluta <daniel.baluta@....com>,
        Mpuaudiosw <Mpuaudiosw@....com>, linux-imx <linux-imx@....com>,
        linux-remoteproc@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        LnxRevLi <LnxRevLi@....com>
Subject: Re: [PATCH 1/2] remoteproc: imx_dsp_rproc: add mandatory
 find_loaded_rsc_table op

On Tue, Jul 18, 2023 at 06:40:53PM +0300, Iuliana Prodan wrote:
> 
> On 7/18/2023 6:23 PM, Mathieu Poirier wrote:
> > On Tue, Jul 18, 2023 at 11:25:03AM +0300, Iuliana Prodan wrote:
> > > On 7/17/2023 8:42 PM, Mathieu Poirier wrote:
> > > > On Thu, Jul 13, 2023 at 01:42:20AM +0300, Iuliana Prodan (OSS) wrote:
> > > > > From: Iuliana Prodan <iuliana.prodan@....com>
> > > > > 
> > > > > Add the .find_loaded_rsc_table operation for i.MX DSP.
> > > > > We need it for inter-process communication between DSP
> > > > > and main core.
> > > > > 
> > > > > This callback is used to find the resource table (defined
> > > > > in remote processor linker script) where the address of the
> > > > > vrings along with the other allocated resources (carveouts etc)
> > > > > are stored.
> > > > > If this is not found, the vrings are not allocated and
> > > > > the IPC between cores will not work.
> > > > Is there a constraint on the system memory the M4 can address?  If so there
> > > > will be a need to declare address ranges for vrings and buffers in reserved
> > > > memory in the DT.
> > > > 
> > > > Thanks,
> > > > Mathieu
> > > Hi Mathieu,
> > > 
> > > No, there is no constraint on memory.
> > > 
> > > We want the Cortex A core to communicate with the HiFi4 DSP.
> > > The Cortex A is in charge of starting the DSP and loading the firmware in
> > > HiFi4's memory.
> > > When using rpmsg for IPC, the Cortex A needs to find the resource table
> > > (defined in the DSP linker script) and this is done using
> > > .find_loaded_rsc_table callback.
> > > 
> > > For the DT, we are using a (not upstream) device tree where we have the
> > > reserved-memory for dsp_vdev0vring0, dsp_vdev0vring1 and dsp_vdev0buffer.
> > That is the part I'm interested in.  Don't we need the reserved-memory entries?
> > Otherwise the M4 may not be able to access the memory chosen by the application
> > processor, most likely leading to a crash.
> 
> This kernel module (imx_dsp_rproc) is used only for DSP.
> For M4 core we use imx_rproc.
>

The point here is that if I merge this patch and someone tries to load a
firmware image that has a resource table, the system will likely crash because
reserved memories haven't been specified in the DT.

Unless there is a very good reason not to, I would like to see the companion DT
changes submitted with this patch so that the feature is complete.

> Iulia
> 
> > > Iulia
> > > 
> > > 
> > > > > Signed-off-by: Iuliana Prodan <iuliana.prodan@....com>
> > > > > ---
> > > > >    drivers/remoteproc/imx_dsp_rproc.c | 1 +
> > > > >    1 file changed, 1 insertion(+)
> > > > > 
> > > > > diff --git a/drivers/remoteproc/imx_dsp_rproc.c b/drivers/remoteproc/imx_dsp_rproc.c
> > > > > index d95fa5586189..b5634507d953 100644
> > > > > --- a/drivers/remoteproc/imx_dsp_rproc.c
> > > > > +++ b/drivers/remoteproc/imx_dsp_rproc.c
> > > > > @@ -941,6 +941,7 @@ static const struct rproc_ops imx_dsp_rproc_ops = {
> > > > >    	.kick		= imx_dsp_rproc_kick,
> > > > >    	.load		= imx_dsp_rproc_elf_load_segments,
> > > > >    	.parse_fw	= imx_dsp_rproc_parse_fw,
> > > > > +	.find_loaded_rsc_table = rproc_elf_find_loaded_rsc_table,
> > > > >    	.sanity_check	= rproc_elf_sanity_check,
> > > > >    	.get_boot_addr	= rproc_elf_get_boot_addr,
> > > > >    };
> > > > > -- 
> > > > > 2.17.1
> > > > >