Re: [igt-dev] [RFC PATCH i-g-t] lib/i915: Generate engine names at runtime

[Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>]

On 15/11/2019 12:14, Petri Latvala wrote:
> The kernel supplies us an engine list with engine class and an
> instance id. If the hardcoded engine list doesn't have the
> class+instance we get, construct the engine name with printf instead
> of calling additional engines "unknown".
> 
> Signed-off-by: Petri Latvala <petri.latvala@intel.com>
> Cc: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
> Cc: Andi Shyti <andi.shyti@intel.com>
> Cc: Katarzyna Dec <katarzyna.dec@intel.com>
> 
> ---
>   lib/i915/gem_engine_topology.c | 27 +++++++++++++++++++--------
>   lib/i915/gem_engine_topology.h |  2 +-
>   lib/igt_gt.c                   |  8 ++++++++
>   lib/igt_gt.h                   |  7 ++++++-
>   4 files changed, 34 insertions(+), 10 deletions(-)
> 
> diff --git a/lib/i915/gem_engine_topology.c b/lib/i915/gem_engine_topology.c
> index 790d455f..0707f237 100644
> --- a/lib/i915/gem_engine_topology.c
> +++ b/lib/i915/gem_engine_topology.c
> @@ -103,6 +103,7 @@ static void init_engine(struct intel_execution_engine2 *e2,
>   	const struct intel_execution_engine2 *__e2;
>   	static const char *unknown_name = "unknown",
>   			  *virtual_name = "virtual";
> +	const struct intel_execution_engine_class *cls;
>   
>   	e2->class    = class;
>   	e2->instance = instance;
> @@ -111,7 +112,7 @@ static void init_engine(struct intel_execution_engine2 *e2,
>   	/* engine is a virtual engine */
>   	if (class == I915_ENGINE_CLASS_INVALID &&
>   	    instance == I915_ENGINE_CLASS_INVALID_VIRTUAL) {
> -		e2->name = virtual_name;
> +		strncpy(e2->name, virtual_name, sizeof(e2->name));
>   		e2->is_virtual = true;
>   		return;
>   	}
> @@ -120,12 +121,22 @@ static void init_engine(struct intel_execution_engine2 *e2,
>   		if (__e2->class == class && __e2->instance == instance)
>   			break;
>   
> -	if (__e2->name) {
> -		e2->name = __e2->name;
> +	if (__e2->name[0]) {
> +		strncpy(e2->name, __e2->name, sizeof(e2->name));
>   	} else {
> -		igt_warn("found unknown engine (%d, %d)\n", class, instance);
> -		e2->name = unknown_name;
> -		e2->flags = -1;
> +		for (cls = intel_execution_engine_class_map; cls->name; cls++) {
> +			if (cls->class == class) {
> +				snprintf(e2->name, sizeof(e2->name), "%s%d", cls->name, instance);
> +				igt_info("unknown but supported engine %s found\n", e2->name);

Hm not really unknown, just a new instance relative to the static table. 
I'd probably downgrade this to debug level?

> +				break;
> +			}
> +		}
> +
> +		if (!e2->name[0]) {
> +			igt_info("found unknown engine (%d, %d)\n", class, instance);
> +			strncpy(e2->name, unknown_name, sizeof(e2->name));

unknown<class>:<instance> ?

And say unknown _class_ in the log message?


> +			e2->flags = -1;
> +		}
>   	}
>   
>   	/* just to remark it */
> @@ -223,7 +234,7 @@ struct intel_engine_data intel_init_engine_list(int fd, uint32_t ctx_id)
>   			struct intel_execution_engine2 *__e2 =
>   				&engine_data.engines[engine_data.nengines];
>   
> -			__e2->name       = e2->name;
> +			strncpy(__e2->name, e2->name, sizeof(__e2->name));
>   			__e2->instance   = e2->instance;
>   			__e2->class      = e2->class;
>   			__e2->flags      = e2->flags;
> @@ -302,7 +313,7 @@ struct intel_execution_engine2 gem_eb_flags_to_engine(unsigned int flags)
>   
>   	if (ring == I915_EXEC_DEFAULT) {
>   		e2__.flags = I915_EXEC_DEFAULT;
> -		e2__.name = "default";
> +		strncpy(e2__.name, "default", sizeof(e2__.name));
>   	} else {
>   		const struct intel_execution_engine2 *e2;
>   
> diff --git a/lib/i915/gem_engine_topology.h b/lib/i915/gem_engine_topology.h
> index d98773e0..525741cc 100644
> --- a/lib/i915/gem_engine_topology.h
> +++ b/lib/i915/gem_engine_topology.h
> @@ -61,7 +61,7 @@ bool gem_engine_is_equal(const struct intel_execution_engine2 *e1,
>   struct intel_execution_engine2 gem_eb_flags_to_engine(unsigned int flags);
>   
>   #define __for_each_static_engine(e__) \
> -	for ((e__) = intel_execution_engines2; (e__)->name; (e__)++)
> +	for ((e__) = intel_execution_engines2; (e__)->name[0]; (e__)++)
>   
>   #define for_each_context_engine(fd__, ctx__, e__) \
>   	for (struct intel_engine_data i__ = intel_init_engine_list(fd__, ctx__); \
> diff --git a/lib/igt_gt.c b/lib/igt_gt.c
> index 256c7cbc..25e6c455 100644
> --- a/lib/igt_gt.c
> +++ b/lib/igt_gt.c
> @@ -596,6 +596,14 @@ const struct intel_execution_engine2 intel_execution_engines2[] = {
>   	{ }
>   };
>   
> +const struct intel_execution_engine_class intel_execution_engine_class_map[] = {
> +	{ "rcs", I915_ENGINE_CLASS_RENDER },
> +	{ "bcs", I915_ENGINE_CLASS_COPY },
> +	{ "vcs", I915_ENGINE_CLASS_VIDEO },
> +	{ "vecs", I915_ENGINE_CLASS_VIDEO_ENHANCE },
> +	{ }
> +};
> +
>   int gem_execbuf_flags_to_engine_class(unsigned int flags)
>   {
>   	switch (flags & 0x3f) {
> diff --git a/lib/igt_gt.h b/lib/igt_gt.h
> index 66088d39..0268031f 100644
> --- a/lib/igt_gt.h
> +++ b/lib/igt_gt.h
> @@ -95,13 +95,18 @@ bool gem_can_store_dword(int fd, unsigned int engine);
>   bool gem_class_can_store_dword(int fd, int class);
>   
>   extern const struct intel_execution_engine2 {
> -	const char *name;
> +	char name[10];
>   	int class;
>   	int instance;
>   	uint64_t flags;
>   	bool is_virtual;
>   } intel_execution_engines2[];
>   
> +extern const struct intel_execution_engine_class {
> +	const char *name;
> +	int class;
> +} intel_execution_engine_class_map[];
> +
>   int gem_execbuf_flags_to_engine_class(unsigned int flags);
>   
>   #endif /* IGT_GT_H */
> 

Implementation looks okay to me, but what does it gains us? Potentially 
introduces a slight confusion between subtests as enumerated by engine 
and engines iterated inside some tests.

Only an interim step before elimination of the static array? But danger 
is in the above mismatch.

Regards,

Tvrtko
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