Re: [PATCH 12/13] drm/i915: Add a CMD_PARSER_VERSION getparam

[Daniel Vetter <daniel@ffwll.ch>]

On Wed, Jan 29, 2014 at 01:55:13PM -0800, bradley.d.volkin@intel.com wrote:
> From: Brad Volkin <bradley.d.volkin@intel.com>
> 
> So userspace can query the kernel for command parser support.
> 
> OTC-Tracker: AXIA-4631
> Change-Id: I58af650db9f6753c2dcac9c54ab432fd31db302f
> Signed-off-by: Brad Volkin <bradley.d.volkin@intel.com>
> ---
>  drivers/gpu/drm/i915/i915_dma.c | 4 ++++
>  include/uapi/drm/i915_drm.h     | 1 +
>  2 files changed, 5 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
> index 258b1be..34ba199 100644
> --- a/drivers/gpu/drm/i915/i915_dma.c
> +++ b/drivers/gpu/drm/i915/i915_dma.c
> @@ -1013,6 +1013,10 @@ static int i915_getparam(struct drm_device *dev, void *data,
>  	case I915_PARAM_HAS_EXEC_HANDLE_LUT:
>  		value = 1;
>  		break;
> +	case I915_PARAM_CMD_PARSER_VERSION:
> +		/* TODO: version info (e.g. what is allowed?) */
> +		value = 1;

I think an increasing integer without any mean special grouping (like
major/minor) is good enough. What we need though is a small revision log
with one-line blurbs that explain what has been added, e.g.

1: Initial version.
2: Allow streamout related registers
3: Add gen8 support

...

I think it would be good to have this as a comment right next to the
parser code itself, so what about adding a i915_cmd_parser_get_version
function to i915_cmd_parser.c who's only job is to return and integer and
contain this comment?
-Daniel

> +		break;
>  	default:
>  		DRM_DEBUG("Unknown parameter %d\n", param->param);
>  		return -EINVAL;
> diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
> index 126bfaa..8a3e4ef00 100644
> --- a/include/uapi/drm/i915_drm.h
> +++ b/include/uapi/drm/i915_drm.h
> @@ -337,6 +337,7 @@ typedef struct drm_i915_irq_wait {
>  #define I915_PARAM_HAS_EXEC_NO_RELOC	 25
>  #define I915_PARAM_HAS_EXEC_HANDLE_LUT   26
>  #define I915_PARAM_HAS_WT     	 	 27
> +#define I915_PARAM_CMD_PARSER_VERSION	 28
>  
>  typedef struct drm_i915_getparam {
>  	int param;
> -- 
> 1.8.5.2
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch