[U-Boot] [PATCH v1] clk: clk-uclass: Check ops pointer before use it

[Stephen Warren]

On 08/17/2016 06:30 PM, Wenyou.Yang at microchip.com wrote:
> HI Stephen,
>
>> -----Original Message-----
>> From: Stephen Warren [mailto:swarren at wwwdotorg.org]
>> Sent: 2016年8月17日 23:59
>> To: Wenyou Yang <wenyou.yang at atmel.com>
>> Cc: U-Boot Mailing List <u-boot at lists.denx.de>; Stephen Warren
>> <swarren at nvidia.com>; Michal Simek <michal.simek at xilinx.com>
>> Subject: Re: [U-Boot] [PATCH v1] clk: clk-uclass: Check ops pointer before use it
>>
>> On 08/17/2016 01:05 AM, Wenyou Yang wrote:
>>> Add check ops pointer before use it. Otherwise, it will cause the
>>> runtime error for the clk devices without ops callback.
>>
>> Other uclasses like reset, power domain, and mailbox don't do this. All drivers
>> must have an ops pointer, or they can't be useful. I'm not sure this patch is
>> necessary. Is it just a debugging aid so if the driver writer forgets to set the ops
>> pointer the system will error out rather than crashing? If so, a post-bind hook in
>> the uclass that refuses the driver if it hasn't set the ops pointer would be better.
>
> Sorry, I don't agree with you.
>
> Not all drivers have an ops pointer.
>
> If you grep U_BOOT_DRIVER , you will find that there are some drivers without an ops pointer.
>
> We should not suppose a driver should have something, I think.

But without an ops pointer, the driver can do nothing and provide no 
services. Why is that useful?