Re: [PATCH v2 1/2] drm/xe: Introduce force-wake guard class

[Rodrigo Vivi <rodrigo.vivi@intel.com>]

On Mon, Nov 18, 2024 at 07:45:10PM +0100, Michal Wajdeczko wrote:
> There is support for 'classes' with constructor and destructor
> semantics that can be used for any scope-based resource management,
> like our domain force-wake management.

There is, okay...
It can be, okay...

But why do we want?
What are the advantages?

> 
> Define xe_fw class that can be used for force-wake management.
> 
> Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
> Cc: Lucas De Marchi <lucas.demarchi@intel.com>
> Cc: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>
> ---
> v2: aligned to new force-wake usage model (Michal)
> ---
>  drivers/gpu/drm/xe/xe_force_wake.h       | 12 ++++++++++++
>  drivers/gpu/drm/xe/xe_force_wake_types.h | 10 ++++++++++
>  2 files changed, 22 insertions(+)
> 
> diff --git a/drivers/gpu/drm/xe/xe_force_wake.h b/drivers/gpu/drm/xe/xe_force_wake.h
> index 0e3e84bfa51c..e46e44f7eb70 100644
> --- a/drivers/gpu/drm/xe/xe_force_wake.h
> +++ b/drivers/gpu/drm/xe/xe_force_wake.h
> @@ -6,6 +6,8 @@
>  #ifndef _XE_FORCE_WAKE_H_
>  #define _XE_FORCE_WAKE_H_
>  
> +#include <linux/cleanup.h>
> +
>  #include "xe_assert.h"
>  #include "xe_force_wake_types.h"
>  
> @@ -61,4 +63,14 @@ xe_force_wake_ref_has_domain(unsigned int fw_ref, enum xe_force_wake_domains dom
>  	return fw_ref & domain;
>  }
>  
> +DEFINE_CLASS(xe_fw, struct xe_force_wake_guard,
> +	     xe_force_wake_put(_T.fw, _T.ref),
> +	     ({ (struct xe_force_wake_guard){ fw, xe_force_wake_get(fw, domains) }; }),
> +	     struct xe_force_wake *fw, enum xe_force_wake_domains domains);
> +
> +static inline void *class_xe_fw_lock_ptr(class_xe_fw_t *_T)
> +{
> +	return _T->ref ? _T : NULL;
> +}
> +
>  #endif
> diff --git a/drivers/gpu/drm/xe/xe_force_wake_types.h b/drivers/gpu/drm/xe/xe_force_wake_types.h
> index 899fbbcb3ea9..15456a24f707 100644
> --- a/drivers/gpu/drm/xe/xe_force_wake_types.h
> +++ b/drivers/gpu/drm/xe/xe_force_wake_types.h
> @@ -85,4 +85,14 @@ struct xe_force_wake {
>  	struct xe_force_wake_domain domains[XE_FW_DOMAIN_ID_COUNT];
>  };
>  
> +/**
> + * struct xe_force_wake_guard - Xe force wake guard
> + */
> +struct xe_force_wake_guard {
> +	/** @fw: force wake manager */
> +	struct xe_force_wake *fw;
> +	/** @ref: opaque reference to woken domains */
> +	unsigned int ref;
> +};
> +
>  #endif
> -- 
> 2.43.0
>