linux-kernel - Re: [PATCH 2/4] clk: tegra: check BPMP response return code

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Message-ID: <5dfbbc6d-0dc0-7d92-0bff-8b05ddd272b3@nvidia.com>
Date:   Fri, 29 Sep 2017 15:53:31 +0100
From:   Jon Hunter <jonathanh@...dia.com>
To:     Timo Alho <talho@...dia.com>,
        "thierry.reding@...il.com" <thierry.reding@...il.com>
CC:     "linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/4] clk: tegra: check BPMP response return code


On 29/09/17 14:46, Timo Alho wrote:
> Hi Jon,
> 
> On 21.09.2017 14:21, Jonathan Hunter wrote:
>>
>>
>> On 07/09/17 10:31, Timo Alho wrote:
>>> Check return code in BPMP response message(s). The typical error case
>>> is when clock operation is attempted with invalid clock identifier.
>>>
>>> Also remove error print from call to clk_get_info() as the
>>> implementation loops through range of all possible identifier, but the
>>> operation is expected error out when the clock id is unused.
>>>
>>> Signed-off-by: Timo Alho <talho@...dia.com>
>>> ---
>>>   drivers/clk/tegra/clk-bpmp.c | 15 ++++++++++-----
>>>   1 file changed, 10 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/drivers/clk/tegra/clk-bpmp.c b/drivers/clk/tegra/clk-bpmp.c
>>> index 638ace6..a896692 100644
>>> --- a/drivers/clk/tegra/clk-bpmp.c
>>> +++ b/drivers/clk/tegra/clk-bpmp.c
>>> @@ -55,6 +55,7 @@ struct tegra_bpmp_clk_message {
>>>       struct {
>>>           void *data;
>>>           size_t size;
>>> +        int ret;
>>>       } rx;
>>>   };
>>>   @@ -64,6 +65,7 @@ static int tegra_bpmp_clk_transfer(struct
>>> tegra_bpmp *bpmp,
>>>       struct mrq_clk_request request;
>>>       struct tegra_bpmp_message msg;
>>>       void *req = &request;
>>> +    int err;
>>>         memset(&request, 0, sizeof(request));
>>>       request.cmd_and_id = (clk->cmd << 24) | clk->id;
>>> @@ -84,7 +86,13 @@ static int tegra_bpmp_clk_transfer(struct
>>> tegra_bpmp *bpmp,
>>>       msg.rx.data = clk->rx.data;
>>>       msg.rx.size = clk->rx.size;
>>>   -    return tegra_bpmp_transfer(bpmp, &msg);
>>> +    err = tegra_bpmp_transfer(bpmp, &msg);
>>> +    if (err < 0)
>>> +        return err;
>>> +    else if (msg.rx.ret < 0)
>>> +        return -EINVAL;
>>
>> I assume that the error codes returned do not correlated to the Linux
>> error codes here. Is that correct? If not we could just return the
>> actual error code. Otherwise would it be useful to print a message with
>> the bpmp error code for debug?
> 
> The error codes are not 1:1 match with Linux. Unfortunately, printing
> message for debug is not either viable as during clock probing we are
> expecting many of the calls to return -BPMP_EINVAL to indicate that
> particular clock ID is unused.

OK. Could it return other errors other than BPMP_EINVAL? I am just
wondering if we need to differentiate between unused and an actual
error? Maybe that is not possible here?

Cheers
Jon

-- 
nvpublic