Re: [PATCH v8 2/8] drm/i915: Update GEM suspend/resume flows considering GuC and GEM fences

[Sagar Arun Kamble <sagar.a.kamble@intel.com>]

On 9/26/2017 7:12 PM, Chris Wilson wrote:
> Quoting Sagar Arun Kamble (2017-09-26 14:24:39)
>> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
>> index dbe181b..5dcd8c0 100644
>> --- a/drivers/gpu/drm/i915/i915_gem.c
>> +++ b/drivers/gpu/drm/i915/i915_gem.c
>> @@ -2022,11 +2022,22 @@ int i915_gem_fault(struct vm_fault *vmf)
>>          intel_runtime_pm_put(i915);
>>   }
>>   
>> +/**
>> + * i915_gem_runtime_suspend() - Finish GEM suspend
>> + * @dev_priv: i915 device private
>> + *
>> + * This function suspends GuC, removes userspace mappings for all GEM obejcts
>> + * currently on userfault list and marks fences if any being used as lost.
>> + *
>> + * Return:     non-zero code on error
>> + */
>> +/**
>> + * i915_gem_runtime_resume() - Restore GEM state
>> + * @dev_priv: i915 device private
>> + *
>> + * This function inits swizzling, restores fences and resumes GuC.
>> + *
>> + * Return:     non-zero code on error
>> + */
>> +/**
>> + * i915_gem_suspend() - Suspend all GT activity.
>> + * @dev_priv: i915 device private
>> + *
>> + * This function disables RPS, flushes all executing context ensuring
>> + * GEM/GT/Engines idleness, cancels all work that needs GT access and suspends
>> + * GuC. In the end currently, it also reset the GEM state and GPU HW.
>> + *
>> + * Return:     non-zero code on error
>> + */
>> +/**
>> + * i915_gem_resume() - Resume GT activity.
>> + * @dev_priv: i915 device private
>> + *
>> + * This function restores GTT mappings, restores fences and resets the
>> + * context images and resumes GuC.
>> + *
>> + * Return:     non-zero code on error
>> + */
> I can very much read what the functions do. These comments blocks are
> for telling me when to call them, under what pre/post-conditions and the
> overall intent of the function.
>
> Who are these blocks for? This isn't a library interface we expect to be
> used, these are hooks.
> -Chris
Since these functions are exported from i915_gem.c and are being used 
from respective drm functions, to make
the semantics available in kernel docs I have added these comments.

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