linux-kernel - Re: [PATCH] firmware: add a function to load optional firmware v2

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Message-ID: <5AA8DC29.2000806@broadcom.com>
Date:   Wed, 14 Mar 2018 09:24:09 +0100
From:   Arend van Spriel <arend.vanspriel@...adcom.com>
To:     Kalle Valo <kvalo@...eaurora.org>,
        "Luis R. Rodriguez" <mcgrof@...nel.org>
Cc:     Andres Rodriguez <andresx7@...il.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-wireless <linux-wireless@...r.kernel.org>
Subject: Re: [PATCH] firmware: add a function to load optional firmware v2

On 3/13/2018 5:46 PM, Kalle Valo wrote:
> "Luis R. Rodriguez" <mcgrof@...nel.org> writes:
>
>> On Tue, Mar 13, 2018 at 03:16:34PM +0200, Kalle Valo wrote:
>>> "Luis R. Rodriguez" <mcgrof@...nel.org> writes:
>>>
>>>>> +/**
>>>>> + * request_firmware_optional: - request for an optional fw module
>>>>> + * @firmware_p: pointer to firmware image
>>>>> + * @name: name of firmware file
>>>>> + * @device: device for which firmware is being loaded
>>>>> + *
>>>>> + * This function is similar in behaviour to request_firmware(), except
>>>>> + * it doesn't produce warning messages when the file is not found.
>>>>> + **/
>>>>> +int
>>>>> +request_firmware_optional(const struct firmware **firmware_p, const char *name,
>>>>> +                         struct device *device)
>>>>> +{
>>>>> +       int ret;
>>>>> +
>>>>> +       /* Need to pin this module until return */
>>>>> +       __module_get(THIS_MODULE);
>>>>> +               ret = _request_firmware(firmware_p, name, device, NULL, 0,
>>>>> +                               FW_OPT_UEVENT | FW_OPT_NO_WARN );
>>>>> +       module_put(THIS_MODULE);
>>>>> +       return ret;
>>>>> +}
>>>>> +EXPORT_SYMBOL(request_firmware_optional);
>>>>
>>>> New exported symbols for the firmware API should be EXPORT_SYMBOL_GPL().
>>>
>>> To me the word optional feels weird to me. For example, in ath10k I
>>> suspect we would be only calling request_firmware_optional() with all
>>> firmware and not request_firmware() at all.
>>>
>>> How about request_firmware_nowarn()? That would even match the
>>> documentation above.
>>
>> _nowarn() works with me. Do you at least want the return value to give
>> an error value if no file was found? This way the driver can decide
>> when to issue an error if it wants to.
>
> Yes, it would be very good to return the error value to ath10k. That way
> we can give a proper error message to the user if we can't find a
> suitable firmware image.

I fully agree with the _nowarn() and returning an error. However, the 
firmware_p parameter (btw. do we really want the _p postfix?) is an 
output parameter which will be null in case of an error so do you really 
need a specific error code for the proper error message.

Regards,
Arend