Re: 回复: [EXT] Re: [PATCH v4 10/20] scmi_protocols: update struct scmi_base_discover_list_protocols_out

[Marek Vasut]

On 3/3/25 11:37 AM, Alice Guo (OSS) wrote:

Hi,

>>> @protocols is an array of protocol identifiers that are implemented,
>>> excluding the Base protocol. The number of elements of @protocols is
>>> specified by callee-side. Currently, set it to 4 is enough for i.MX95.
>> Can you please try something like this instead ? That should be
>> future-proof:
>>
>> diff --git a/drivers/firmware/scmi/base.c b/drivers/firmware/scmi/base.c index
>> f4e3974ff5b..92d278edfaf 100644
>> --- a/drivers/firmware/scmi/base.c
>> +++ b/drivers/firmware/scmi/base.c
>> @@ -258,17 +258,16 @@ static int
>> scmi_base_discover_impl_version_int(struct udevice *dev,
>>    static int scmi_base_discover_list_protocols_int(struct udevice *dev,
>>                                                   u8 **protocols)
>>    {
>> -       struct scmi_base_discover_list_protocols_out out;
>> +       struct scmi_base_discover_list_protocols_out *out;
>>          int cur;
>>          struct scmi_msg msg = {
>>                  .protocol_id = SCMI_PROTOCOL_ID_BASE,
>>                  .message_id = SCMI_BASE_DISCOVER_LIST_PROTOCOLS,
>>                  .in_msg = (u8 *)&cur,
>>                  .in_msg_sz = sizeof(cur),
>> -               .out_msg = (u8 *)&out,
>> -               .out_msg_sz = sizeof(out),
> 
> The pointer and byte size of the buffer where the response message is stored should be provided before sending a BASE_DISCOVER_LIST PROTOCOLS message.
> 
> There is a more reasonable way. Number of protocols that are implemented, excluding the Base protocol, can be obtained by sending a PROTOCOL_ATTRIBUTES message. But now this command is not supported in U-Boot. In this patch, ec8727b7e1 ("firmware: scmi: implement SCMI base protocol"), "u32 protocols[3];" is used. So, I think setting the array of packed SCMI protocol ID's to a fixed size is acceptable.
NAK, let's not perpetuate this suboptimal implementation, please 
implement PROTOCOL_ATTRIBUTES if that's the way to find out the amount 
of supported protocols dynamically.