linux-kernel - Re: [PATCH V5 3/4] interconnect: qcom: Add EPSS L3 support on SA8775P

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Message-ID: <b4716d0d-fcae-4d64-832a-96ecb0a233a7@oss.qualcomm.com>
Date: Fri, 22 Nov 2024 13:46:44 +0100
From: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
To: Raviteja Laggyshetty <quic_rlaggysh@...cinc.com>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Georgi Djakov <djakov@...nel.org>, Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konradybcio@...nel.org>
Cc: Odelu Kukatla <quic_okukatla@...cinc.com>,
        Mike Tipton <quic_mdtipton@...cinc.com>,
        Sibi Sankar
 <quic_sibis@...cinc.com>, linux-arm-msm@...r.kernel.org,
        linux-pm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH V5 3/4] interconnect: qcom: Add EPSS L3 support on SA8775P

On 21.11.2024 7:03 PM, Raviteja Laggyshetty wrote:
> 
> 
> On 11/21/2024 5:28 PM, Krzysztof Kozlowski wrote:
>> On 21/11/2024 12:30, Raviteja Laggyshetty wrote:
>>> Add Epoch Subsystem (EPSS) L3 interconnect provider on
>>> SA8775P SoCs with multiple device support.
>>>
>>
>>
>> ...
>>
>>> -DEFINE_QNODE(osm_l3_master, OSM_L3_MASTER_NODE, 16, OSM_L3_SLAVE_NODE);
>>> -DEFINE_QNODE(osm_l3_slave, OSM_L3_SLAVE_NODE, 16);
>>> +DEFINE_QNODE(osm_l3_master, 16, osm_l3_slave);
>>> +DEFINE_QNODE(osm_l3_slave, 16);
>>>  
>>> -static const struct qcom_osm_l3_node * const osm_l3_nodes[] = {
>>> +static struct qcom_osm_l3_node * const osm_l3_nodes[] = {
>>>  	[MASTER_OSM_L3_APPS] = &osm_l3_master,
>>>  	[SLAVE_OSM_L3] = &osm_l3_slave,
>>>  };
>>>  
>>> -DEFINE_QNODE(epss_l3_master, OSM_L3_MASTER_NODE, 32, OSM_L3_SLAVE_NODE);
>>> -DEFINE_QNODE(epss_l3_slave, OSM_L3_SLAVE_NODE, 32);
>>> +DEFINE_QNODE(epss_l3_master, 32, epss_l3_slave);
>>> +DEFINE_QNODE(epss_l3_slave, 32);
>>>  
>>> -static const struct qcom_osm_l3_node * const epss_l3_nodes[] = {
>>> +static struct qcom_osm_l3_node * const epss_l3_nodes[] = {
>>
>>
>> I think dropping const makes the code worse, not better. Commit msg does
>> not explain all these changes and I could not figure out the intention
>> (except modifying but that's just obvious).
> 
> EPSS L3 on SA8775P has two instances and this requires creation of two device nodes in devicetree.
> As Interconnect framework requires a unique node id, each device node needs to have different compatible and data.
> To overcome the need of having two different compatibles and data, driver code has been modified to acquire unique node id from IDA 
> and the node name is made dynamic (nodename@...ress).
> Updating node id and node name is not possible with const.

I think it would be better to just fix the interconnect API to do it
internally

Konrad