[dpdk-dev] [PATCH] librte_ethdev: extend dpdk api led control to query capability

[Ferruh Yigit]

On 1/8/2020 8:56 AM, David Marchand wrote:
> Hello Laurent,
> 
> Bonne année.
> 
> Cc: maintainers.
> 
> On Tue, Jan 7, 2020 at 3:57 PM Laurent Hardy <laurent.hardy at 6wind.com> wrote:
>>
>> In current led control API we have no way to know if a device is able
>> to handle on/off requests coming from the application.
>> Knowing if the device is led control capable could be useful to avoid
>> exchanges between application and kernel.
>> Using the on/off requests to flag if the device is led control capable
>> (based on the ENOSUP returned error) is not convenient as such request
>> can change the led state on device.
>>
>> This patch adds a new function rte_eth_led_ctrl_capable() that will look
>> for led_off/on dev ops availability on the related pmd, to know if the
>> device is able to handle such led control requests (on/off).
> 
> This patch breaks the ABI, which is BAD :-).

Why it is an ABI break, dev_ops should be between library and drivers, so it
should be out of the ABI concern, isn't it.

> This new api only needs to look at the existing ops, so you can remove
> the (unused in your patch) dev_led_ctrl_capable ops.
> 
> OTOH, would it make sense to expose this capability in dev_flags?
> 

'rte_eth_led_on()' & 'rte_eth_led_off()' APIs returns '-ENOTSUP' when the not
supported, can that help application to understand?