[igt-dev] [PATCH i-g-t] lib/i915: Return actual submission method from gem_submission_method

[John Harrison]

On 10/15/2021 17:23, Ashutosh Dixit wrote:
> gem_submission_method() purports to return the currently used submission
> method by the driver, as evidenced by its callers. Therefore remove the
> GEM_SUBMISSION_EXECLISTS flag when GuC submission is detected.
>
> This also fixes gem_has_execlists() to match its description, previously
> gem_has_execlists() would return true even if GuC submission was actually
> being used in the driver.
>
> Reported-by: John Harrison <john.c.harrison at intel.com>
> Cc: Tvrtko Ursulin <tvrtko.ursulin at linux.intel.com>
> Signed-off-by: Ashutosh Dixit <ashutosh.dixit at intel.com>
> ---
>   lib/i915/gem_submission.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/lib/i915/gem_submission.c b/lib/i915/gem_submission.c
> index 2627b802cfb..b037d04cc4a 100644
> --- a/lib/i915/gem_submission.c
> +++ b/lib/i915/gem_submission.c
> @@ -86,7 +86,7 @@ unsigned gem_submission_method(int fd)
>   		return 0;
>   
>   	if (igt_sysfs_get_u32(dir, "enable_guc") & 1) {
> -		flags |= GEM_SUBMISSION_GUC | GEM_SUBMISSION_EXECLISTS;
> +		flags |= GEM_SUBMISSION_GUC;
>   		goto out;
>   	}
>   
Looks good to me, but as per the comments in the other thread, this 
might have unintended side effects. Have you gone through all instances 
of the submission query usages to check how it is used and whether this 
will break something? E.g. if something is explicitly testing for 
execlist support to mean 'something better than ring buffer' then it 
would now fail.


John.