Re: [PATCH 03/43] drm/i915/bdw: Macro for LRCs and module option for Execlists

[Daniel Vetter <daniel@ffwll.ch>]

On Thu, Jul 24, 2014 at 05:04:11PM +0100, Thomas Daniel wrote:
> From: Oscar Mateo <oscar.mateo@intel.com>
> 
> GEN8 brings an expansion of the HW contexts: "Logical Ring Contexts".
> These expanded contexts enable a number of new abilities, especially
> "Execlists".
> 
> The macro is defined to off until we have things in place to hope to
> work.
> 
> v2: Rename "advanced contexts" to the more correct "logical ring
> contexts".
> 
> v3: Add a module parameter to enable execlists. Execlist are relatively
> new, and so it'd be wise to be able to switch back to ring submission
> to debug subtle problems that will inevitably arise.
> 
> v4: Add an intel_enable_execlists function.
> 
> v5: Sanitize early, as suggested by Daniel. Remove lrc_enabled.
> 
> Signed-off-by: Ben Widawsky <ben@bwidawsk.net> (v1)
> Signed-off-by: Damien Lespiau <damien.lespiau@intel.com> (v3)
> Signed-off-by: Oscar Mateo <oscar.mateo@intel.com> (v2, v4 & v5)
> ---
>  drivers/gpu/drm/i915/i915_drv.h    |    2 ++
>  drivers/gpu/drm/i915/i915_gem.c    |    3 +++
>  drivers/gpu/drm/i915/i915_params.c |    6 ++++++
>  drivers/gpu/drm/i915/intel_lrc.c   |   11 +++++++++++
>  drivers/gpu/drm/i915/intel_lrc.h   |    3 +++
>  5 files changed, 25 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 54c2bd9..a793d6d 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -2037,6 +2037,7 @@ struct drm_i915_cmd_table {
>  #define I915_NEED_GFX_HWS(dev)	(INTEL_INFO(dev)->need_gfx_hws)
>  
>  #define HAS_HW_CONTEXTS(dev)	(INTEL_INFO(dev)->gen >= 6)
> +#define HAS_LOGICAL_RING_CONTEXTS(dev)	0
>  #define HAS_ALIASING_PPGTT(dev)	(INTEL_INFO(dev)->gen >= 6)
>  #define HAS_PPGTT(dev)		(INTEL_INFO(dev)->gen >= 7 && !IS_GEN8(dev))
>  #define USES_PPGTT(dev)		intel_enable_ppgtt(dev, false)
> @@ -2122,6 +2123,7 @@ struct i915_params {
>  	int enable_rc6;
>  	int enable_fbc;
>  	int enable_ppgtt;
> +	int enable_execlists;
>  	int enable_psr;
>  	unsigned int preliminary_hw_support;
>  	int disable_power_well;
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index e5d4d73..d8bf4fa 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -4746,6 +4746,9 @@ int i915_gem_init(struct drm_device *dev)
>  	struct drm_i915_private *dev_priv = dev->dev_private;
>  	int ret;
>  
> +	i915.enable_execlists = intel_sanitize_enable_execlists(dev,
> +			i915.enable_execlists);

The ordering constraint on i915.enabel_ppgtt sanitization is imo
super-fragile. You'll all get a big price (and grumpy maintainer) if this
blows up. I'll add a patch on top to WARN about this.
-Daniel

> +
>  	mutex_lock(&dev->struct_mutex);
>  
>  	if (IS_VALLEYVIEW(dev)) {
> diff --git a/drivers/gpu/drm/i915/i915_params.c b/drivers/gpu/drm/i915/i915_params.c
> index bbdee21..7f0fb72 100644
> --- a/drivers/gpu/drm/i915/i915_params.c
> +++ b/drivers/gpu/drm/i915/i915_params.c
> @@ -35,6 +35,7 @@ struct i915_params i915 __read_mostly = {
>  	.vbt_sdvo_panel_type = -1,
>  	.enable_rc6 = -1,
>  	.enable_fbc = -1,
> +	.enable_execlists = -1,
>  	.enable_hangcheck = true,
>  	.enable_ppgtt = -1,
>  	.enable_psr = 1,
> @@ -117,6 +118,11 @@ MODULE_PARM_DESC(enable_ppgtt,
>  	"Override PPGTT usage. "
>  	"(-1=auto [default], 0=disabled, 1=aliasing, 2=full)");
>  
> +module_param_named(enable_execlists, i915.enable_execlists, int, 0400);
> +MODULE_PARM_DESC(enable_execlists,
> +	"Override execlists usage. "
> +	"(-1=auto [default], 0=disabled, 1=enabled)");
> +
>  module_param_named(enable_psr, i915.enable_psr, int, 0600);
>  MODULE_PARM_DESC(enable_psr, "Enable PSR (default: true)");
>  
> diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
> index 49bb6fc..21f7f1c 100644
> --- a/drivers/gpu/drm/i915/intel_lrc.c
> +++ b/drivers/gpu/drm/i915/intel_lrc.c
> @@ -40,3 +40,14 @@
>  #include <drm/drmP.h>
>  #include <drm/i915_drm.h>
>  #include "i915_drv.h"
> +
> +int intel_sanitize_enable_execlists(struct drm_device *dev, int enable_execlists)
> +{
> +	if (enable_execlists == 0)
> +		return 0;
> +
> +	if (HAS_LOGICAL_RING_CONTEXTS(dev) && USES_PPGTT(dev))
> +		return 1;
> +
> +	return 0;
> +}
> diff --git a/drivers/gpu/drm/i915/intel_lrc.h b/drivers/gpu/drm/i915/intel_lrc.h
> index f6830a4..75ee9c3 100644
> --- a/drivers/gpu/drm/i915/intel_lrc.h
> +++ b/drivers/gpu/drm/i915/intel_lrc.h
> @@ -24,4 +24,7 @@
>  #ifndef _INTEL_LRC_H_
>  #define _INTEL_LRC_H_
>  
> +/* Execlists */
> +int intel_sanitize_enable_execlists(struct drm_device *dev, int enable_execlists);
> +
>  #endif /* _INTEL_LRC_H_ */
> -- 
> 1.7.9.5
> 
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx

-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch