linux-kernel - Re: [PATCH v4 2/3] remoteproc: qcom: pas: make region assign more generic

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Message-ID: <374addd2-e336-4625-9e0c-45e5efe1eb47@linaro.org>
Date:   Mon, 11 Dec 2023 10:37:27 +0100
From:   Neil Armstrong <neil.armstrong@...aro.org>
To:     Konrad Dybcio <konrad.dybcio@...aro.org>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Manivannan Sadhasivam <mani@...nel.org>
Cc:     linux-arm-msm@...r.kernel.org, linux-remoteproc@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        Mukesh Ojha <quic_mojha@...cinc.com>
Subject: Re: [PATCH v4 2/3] remoteproc: qcom: pas: make region assign more
 generic

On 09/12/2023 19:06, Konrad Dybcio wrote:
> On 8.12.2023 16:04, Neil Armstrong wrote:
>> The current memory region assign only supports a single
>> memory region.
>>
>> But new platforms introduces more regions to make the
>> memory requirements more flexible for various use cases.
>> Those new platforms also shares the memory region between the
>> DSP and HLOS.
>>
>> To handle this, make the region assign more generic in order
>> to support more than a single memory region and also permit
>> setting the regions permissions as shared.
>>
>> Reviewed-by: Mukesh Ojha <quic_mojha@...cinc.com>
>> Signed-off-by: Neil Armstrong <neil.armstrong@...aro.org>
>> ---
> [...]
> 
>> +	for (offset = 0; offset < adsp->region_assign_count; ++offset) {
>> +		struct reserved_mem *rmem = NULL;
>> +
>> +		node = of_parse_phandle(adsp->dev->of_node, "memory-region",
>> +					adsp->region_assign_idx + offset);
>> +		if (node)
>> +			rmem = of_reserved_mem_lookup(node);
>> +		of_node_put(node);
> Shouldn't this only be called when parse_phandle succeeds? (separate
> patch with a fix + cc stable if so?)

It's not a bug, it was added like that because of_node_put() already
checks for a NULL pointer:
https://elixir.bootlin.com/linux/v6.7-rc5/source/drivers/of/dynamic.c#L45

> 
>> +		if (!rmem) {
>> +			dev_err(adsp->dev, "unable to resolve shareable memory-region index %d\n",
>> +				offset);
>> +			return -EINVAL;
>> +		}
>>   
>> -	perm.vmid = QCOM_SCM_VMID_MSS_MSA;
>> -	perm.perm = QCOM_SCM_PERM_RW;
>> +		if (adsp->region_assign_shared)  {
>> +			perm[0].vmid = QCOM_SCM_VMID_HLOS;
>> +			perm[0].perm = QCOM_SCM_PERM_RW;
>> +			perm[1].vmid = adsp->region_assign_vmid;
>> +			perm[1].perm = QCOM_SCM_PERM_RW;
>> +			perm_size = 2;
>> +		} else {
>> +			perm[0].vmid = adsp->region_assign_vmid;
>> +			perm[0].perm = QCOM_SCM_PERM_RW;
>> +			perm_size = 1;
>> +		}
>>   
>> -	adsp->region_assign_phys = rmem->base;
>> -	adsp->region_assign_size = rmem->size;
>> -	adsp->region_assign_perms = BIT(QCOM_SCM_VMID_HLOS);
>> +		adsp->region_assign_phys[offset] = rmem->base;
>> +		adsp->region_assign_size[offset] = rmem->size;
>> +		adsp->region_assign_perms[offset] = BIT(QCOM_SCM_VMID_HLOS);
>>   
>> -	ret = qcom_scm_assign_mem(adsp->region_assign_phys,
>> -				  adsp->region_assign_size,
>> -				  &adsp->region_assign_perms,
> I think this should be renamed to region_assign_owner(s)

Why ? this bitfield is names "perms" everywhere qcom_scm_assign_mem is used

> 
>> -				  &perm, 1);
>> -	if (ret < 0) {
>> -		dev_err(adsp->dev, "assign memory failed\n");
>> -		return ret;
>> +		ret = qcom_scm_assign_mem(adsp->region_assign_phys[offset],
>> +					  adsp->region_assign_size[offset],
>> +					  &adsp->region_assign_perms[offset],
>> +					  perm, perm_size);
>> +		if (ret < 0) {
>> +			dev_err(adsp->dev, "assign memory %d failed\n", offset);
>> +			return ret;
>> +		}
>>   	}
>>   
>>   	return 0;
>> @@ -629,20 +653,23 @@ static int adsp_assign_memory_region(struct qcom_adsp *adsp)
>>   static void adsp_unassign_memory_region(struct qcom_adsp *adsp)
>>   {
>>   	struct qcom_scm_vmperm perm;
>> +	int offset;
>>   	int ret;
>>   
>> -	if (!adsp->region_assign_idx)
>> +	if (!adsp->region_assign_idx || adsp->region_assign_shared)
> So when it's *shared*, we don't want to un-assign it?

Exact, when shared the region stays shared, as downstream does, un-assigning will fail
in this case.

> 
> Konrad

Thanks,
Neil