[Intel-gfx] [PATCH igt 2/2] igt/perf_pmu: Explicitly reset min_freq before max_freq

[Tvrtko Ursulin]

On 22/11/2017 19:00, Chris Wilson wrote:
> The kernel doesn't like it when you set max_freq < min_freq and
> complains bitterly. So before setting max_freq = min_freq, first set
> min_freq to min_freq!
> 
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> ---
>   tests/perf_pmu.c | 4 ++++
>   1 file changed, 4 insertions(+)
> 
> diff --git a/tests/perf_pmu.c b/tests/perf_pmu.c
> index bcb90c84..b8422211 100644
> --- a/tests/perf_pmu.c
> +++ b/tests/perf_pmu.c
> @@ -946,6 +946,8 @@ test_frequency(int gem_fd)
>   	min_freq = igt_sysfs_get_u32(sysfs, "gt_RPn_freq_mhz");
>   	max_freq = igt_sysfs_get_u32(sysfs, "gt_RP0_freq_mhz");
>   	boost_freq = igt_sysfs_get_u32(sysfs, "gt_boost_freq_mhz");
> +	igt_info("Frequency: min=%u, max=%u, boost=%u MHz\n",
> +		 min_freq, max_freq, boost_freq);
>   	igt_require(min_freq > 0 && max_freq > 0 && boost_freq > 0);
>   	igt_require(max_freq > min_freq);
>   	igt_require(boost_freq > min_freq);
> @@ -956,6 +958,8 @@ test_frequency(int gem_fd)
>   	/*
>   	 * Set GPU to min frequency and read PMU counters.
>   	 */
> +	igt_require(igt_sysfs_set_u32(sysfs, "gt_min_freq_mhz", min_freq));
> +	igt_require(igt_sysfs_get_u32(sysfs, "gt_min_freq_mhz") == min_freq);
>   	igt_require(igt_sysfs_set_u32(sysfs, "gt_max_freq_mhz", min_freq));
>   	igt_require(igt_sysfs_get_u32(sysfs, "gt_max_freq_mhz") == min_freq);
>   	igt_require(igt_sysfs_set_u32(sysfs, "gt_boost_freq_mhz", min_freq));
> 

I don't see any harm, but also don't see how min freq is not min freq at 
this point. Dealing with random state on the system or some lack of 
cleanup from the test itself?

Anyway,

Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>

Regards,

Tvrtko