[Intel-gfx] [PATCH] drm/i915/fbc: add comments to the FBC auxiliary structs

[Daniel Vetter]

On Fri, Jul 14, 2017 at 04:38:22PM -0300, Paulo Zanoni wrote:
> I wrote this code an year and a half ago and I couldn't exactly
> remember the main differences of these two structures when reviewing a
> new FBC patch. Add some comments to help explain what's the purpose of
> each struct.
> 
> For the record, the original commits are:
>  b183b3f14395 ("drm/i915/fbc: introduce struct intel_fbc_reg_params")
>  aaf78d276ba0 ("drm/i915/fbc: introduce struct intel_fbc_state_cache")
> 
> Cc: Praveen Paneri <praveen.paneri at intel.com>
> Signed-off-by: Paulo Zanoni <paulo.r.zanoni at intel.com>

Make them kerneldoc? It allows in-line comment, and maybe we'll have
proper kerneldoc for all our structs eventually. Either way

Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch>

> ---
>  drivers/gpu/drm/i915/i915_drv.h | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index a1eeb489..271402c 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -1063,6 +1063,11 @@ struct intel_fbc {
>  	bool underrun_detected;
>  	struct work_struct underrun_work;
>  
> +	/*
> +	 * Due to the atomic rules we can't access some structures without the
> +	 * appropriate locking, so we cache information here in order to avoid
> +	 * these problems.
> +	 */
>  	struct intel_fbc_state_cache {
>  		struct i915_vma *vma;
>  
> @@ -1084,6 +1089,13 @@ struct intel_fbc {
>  		} fb;
>  	} state_cache;
>  
> +	/*
> +	 * This structure contains everything that's relevant to program the
> +	 * hardware registers. When we want to figure out if we need to disable
> +	 * and re-enable FBC for a new configuration we just check if there's
> +	 * something different in the struct. The genx_fbc_activate functions
> +	 * are supposed to read from it in order to program the registers.
> +	 */
>  	struct intel_fbc_reg_params {
>  		struct i915_vma *vma;
>  
> -- 
> 2.9.4
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch