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

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Message-ID: <fc9729a7-53fb-f609-be6a-6454cc69548f@nvidia.com>
Date:   Fri, 29 Sep 2017 16:46:53 +0300
From:   Timo Alho <talho@...dia.com>
To:     Jonathan Hunter <jonathanh@...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

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.

-Timo