DRM_TEGRA_SUBMIT_BUF_WRITE_RELOC

[Mikko Perttunen]

On 9/11/20 1:15 AM, Dmitry Osipenko wrote:
> 09.09.2020 11:10, Mikko Perttunen пишет:
>> On 9/9/20 2:45 AM, Dmitry Osipenko wrote:
>>> 05.09.2020 13:34, Mikko Perttunen пишет:
>>> ...
>>>> +/* Submission */
>>>> +
>>>> +/** Patch address of the specified mapping in the submitted gather. */
>>>> +#define DRM_TEGRA_SUBMIT_BUF_WRITE_RELOC        (1<<0)
>>>
>>> Shouldn't the kernel driver be aware about what relocations need to be
>>> patched? Could you please explain the purpose of this flag?
>>>
>>
>> Sure, the kernel knows if it returned the IOVA to the user or not, so we
>> could remove this flag and determine it implicitly. I don't think there
>> is much harm in it though; if we have the flag an application can decide
>> to ignore the iova field and just pass WRITE_RELOC always, and it's not
>> really any extra code on kernel side.
> 
> Sounds like there is no real practical use for this flag other than for
> testing purposes, correct?
> 

Patching depending just on if the MAP IOCTL returned an IOVA or not 
seems a bit "spooky action at a distance"-ish to me, but maybe it's not 
so bad.. I'll consider removing it.

Mikko