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Date:   Tue, 18 Jul 2023 09:23:15 -0600
From:   Mathieu Poirier <mathieu.poirier@linaro.org>
To:     Iuliana Prodan <iuliana.prodan@nxp.com>
Cc:     "Iuliana Prodan (OSS)" <iuliana.prodan@oss.nxp.com>,
        Bjorn Andersson <andersson@kernel.org>,
        Shawn Guo <shawnguo@kernel.org>,
        Sascha Hauer <s.hauer@pengutronix.de>,
        "S.J. Wang" <shengjiu.wang@nxp.com>,
        Fabio Estevam <festevam@gmail.com>,
        Daniel Baluta <daniel.baluta@nxp.com>,
        Mpuaudiosw <Mpuaudiosw@nxp.com>, linux-imx <linux-imx@nxp.com>,
        linux-remoteproc@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        Pengutronix Kernel Team <kernel@pengutronix.de>,
        LnxRevLi <LnxRevLi@nxp.com>
Subject: Re: [PATCH 1/2] remoteproc: imx_dsp_rproc: add mandatory
 find_loaded_rsc_table op
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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@nxp.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.

> 
> Iulia
> 
> 
> > > Signed-off-by: Iuliana Prodan <iuliana.prodan@nxp.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
> > >