linux-kernel - Re: [PATCH 07/13] scpi: ignore init_versions failure if reported not supported

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Message-ID: <5e627a97-88f6-c7cf-1d64-6439cb708aff@arm.com>
Date:   Tue, 23 Aug 2016 15:54:17 +0100
From:   Sudeep Holla <sudeep.holla@....com>
To:     Neil Armstrong <narmstrong@...libre.com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Cc:     Sudeep Holla <sudeep.holla@....com>,
        linux-amlogic@...ts.infradead.org, khilman@...libre.com,
        heiko@...ech.de, wxt@...k-chips.com, frank.wang@...k-chips.com
Subject: Re: [PATCH 07/13] scpi: ignore init_versions failure if reported not
 supported



On 23/08/16 09:23, Neil Armstrong wrote:
> On 08/19/2016 06:46 PM, Sudeep Holla wrote:
>>
>>
>> On 18/08/16 11:11, Neil Armstrong wrote:
>>> In Amlogic GXBB Legacy SCPI, the LEGACY_SCPI_CMD_SCPI_CAPABILITIES report
>>> as SCPI_ERR_SUPPORT, so do not fail if this command is not supported.
>>>
>>> Signed-off-by: Neil Armstrong <narmstrong@...libre.com>
>>> ---
>>>  drivers/firmware/arm_scpi.c | 12 +++++++-----
>>>  1 file changed, 7 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/drivers/firmware/arm_scpi.c b/drivers/firmware/arm_scpi.c
>>> index 3fe39fe..d3be4c5 100644
>>> --- a/drivers/firmware/arm_scpi.c
>>> +++ b/drivers/firmware/arm_scpi.c
>>> @@ -1111,12 +1111,13 @@ err:
>>>          ret = scpi_info->ops->init_versions(scpi_info);
>>>      else
>>>      ret = scpi_init_versions(scpi_info);
>>> -    if (ret) {
>>> +    if (ret && ret != -EOPNOTSUPP) {
>>>          dev_err(dev, "incorrect or no SCP firmware found\n");
>>>          scpi_remove(pdev);
>>>          return ret;
>>>      }
>>>
>>
>> Why not deal it in init_versions itself.
>>
>>> +    if (ret != -EOPNOTSUPP) {
>>>      _dev_info(dev, "SCP Protocol %d.%d Firmware %d.%d.%d version\n",
>>>            PROTOCOL_REV_MAJOR(scpi_info->protocol_version),
>>>            PROTOCOL_REV_MINOR(scpi_info->protocol_version),
>>
>> Why not have default value like 0.0 ? Just add a comment. Since get
>> version is exported out, IMO having default value makes more sense. What
>> do you think ?
>>
>>> @@ -1124,15 +1125,16 @@ err:
>>>            FW_REV_MINOR(scpi_info->firmware_version),
>>>            FW_REV_PATCH(scpi_info->firmware_version));
>>>
>>> +        ret = sysfs_create_groups(&dev->kobj, versions_groups);
>>> +        if (ret)
>>> +            dev_err(dev, "unable to create sysfs version group\n");
>>> +    }
>>> +
>>
>> Again this can stay as is if we have default.
>>
>
> Printing version 0.0 firmware 0.0.0 is a nonsense for me...
>

OK 0.0 was a wrong example. May be 0.1 ?

Since the driver has already exposed, hypothetically user-space can use
that information, so IMO, we need to expose some static version for pre-v1.0

I am surprised that capability is not supported as this was present even
in that legacy SCPI. Do you know what happens if you send that command ?
Have you done some experiments on that ?

-- 
Regards,
Sudeep