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

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Message-ID: <132d1906-fcea-729d-e226-f3c70ad4090b@nxp.com>
Date:   Tue, 5 Sep 2023 01:31:18 +0300
From:   Iuliana Prodan <iuliana.prodan@....com>
To:     Mathieu Poirier <mathieu.poirier@...aro.org>
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 9/5/2023 12:16 AM, Mathieu Poirier wrote:
> 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.
TBH, so far, I haven't realized that those reserved-memory nodes are not 
upstream
I see they are, as examples, in fsl,dsp.yaml [1]

Let me check why is that and I'll get back - hope, with the DT changes.

[1] 
https://elixir.bootlin.com/linux/latest/source/Documentation/devicetree/bindings/dsp/fsl,dsp.yaml#L170

>> 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
>>>>>>