Re: [PATCH i-g-t] tests/pm_backlight: Add backlight test

[Jani Nikula <jani.nikula@linux.intel.com>]

On Sat, 23 May 2015, Antti Koskipaa <antti.koskipaa@linux.intel.com> wrote:
> This is a basic sanity test of the backlight sysfs interface.
>
> Issue: VIZ-3377
> Signed-off-by: Antti Koskipaa <antti.koskipaa@linux.intel.com>
> ---
>  tests/.gitignore       |   1 +
>  tests/Makefile.sources |   1 +
>  tests/pm_backlight.c   | 144 +++++++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 146 insertions(+)
>  create mode 100644 tests/pm_backlight.c
>
> diff --git a/tests/.gitignore b/tests/.gitignore
> index a3f3143..f816ded 100644
> --- a/tests/.gitignore
> +++ b/tests/.gitignore
> @@ -150,6 +150,7 @@ kms_vblank
>  kms_crtc_background_color
>  kms_plane_scaling
>  kms_panel_fitting
> +pm_backlight
>  pm_lpsp
>  pm_rc6_residency
>  pm_rpm
> diff --git a/tests/Makefile.sources b/tests/Makefile.sources
> index 994c31b..d2a44e8 100644
> --- a/tests/Makefile.sources
> +++ b/tests/Makefile.sources
> @@ -80,6 +80,7 @@ TESTS_progs_M = \
>  	kms_crtc_background_color \
>  	kms_plane_scaling \
>  	kms_panel_fitting \
> +	pm_backlight \
>  	pm_lpsp \
>  	pm_rpm \
>  	pm_rps \
> diff --git a/tests/pm_backlight.c b/tests/pm_backlight.c
> new file mode 100644
> index 0000000..eb2dcf5
> --- /dev/null
> +++ b/tests/pm_backlight.c
> @@ -0,0 +1,144 @@
> +/*
> + * Copyright © 2015 Intel Corporation
> + *
> + * Permission is hereby granted, free of charge, to any person obtaining a
> + * copy of this software and associated documentation files (the "Software"),
> + * to deal in the Software without restriction, including without limitation
> + * the rights to use, copy, modify, merge, publish, distribute, sublicense,
> + * and/or sell copies of the Software, and to permit persons to whom the
> + * Software is furnished to do so, subject to the following conditions:
> + *
> + * The above copyright notice and this permission notice (including the next
> + * paragraph) shall be included in all copies or substantial portions of the
> + * Software.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
> + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
> + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
> + * IN THE SOFTWARE.
> + *
> + * Author:
> + *    Antti Koskipaa <antti.koskipaa@linux.intel.com>
> + *
> + */
> +
> +#include <limits.h>
> +#include <sys/types.h>
> +#include <sys/stat.h>
> +#include <fcntl.h>
> +#include <stdio.h>
> +#include <errno.h>
> +#include <unistd.h>
> +
> +#include "igt_core.h"
> +
> +#define TOLERANCE 5 /* percent */
> +#define BACKLIGHT_PATH "/sys/class/backlight/intel_backlight"
> +
> +IGT_TEST_DESCRIPTION("Basic backlight sysfs test");
> +
> +static int backlight_read(int *result, const char *fname)
> +{
> +	int fd;
> +	char full[PATH_MAX];
> +	char dst[64];
> +	int r, e;
> +
> +	igt_assert(snprintf(full, PATH_MAX, "%s/%s", BACKLIGHT_PATH, fname) < PATH_MAX);
> +
> +	fd = open(full, O_RDONLY);
> +	if (fd == -1)
> +		return -errno;
> +
> +	r = read(fd, dst, sizeof(dst));
> +	e = errno;
> +	close(fd);
> +
> +	if (r < 0)
> +		return -e;
> +
> +	errno = 0;
> +	*result = strtol(dst, NULL, 10);
> +	return errno;
> +}
> +
> +static int backlight_write(int value, const char *fname)
> +{
> +	int fd;
> +	char full[PATH_MAX];
> +	char src[64];
> +	int len;
> +
> +	igt_assert(snprintf(full, PATH_MAX, "%s/%s", BACKLIGHT_PATH, fname) < PATH_MAX);
> +	fd = open(full, O_WRONLY);
> +	if (fd == -1)
> +		return -errno;
> +
> +	len = snprintf(src, sizeof(src), "%i", value);
> +	len = write(fd, src, len);
> +	close(fd);
> +
> +	if (len < 0)
> +		return len;
> +
> +	return 0;
> +}
> +
> +static void test_and_verify(int val, int max)
> +{
> +	int result;
> +	igt_assert(backlight_write(val, "brightness") == 0);
> +	igt_assert(backlight_read(&result, "actual_brightness") == 0);
> +	/* Some rounding may happen depending on hw. Just check that it's close enough. */
> +	igt_assert(result <= val + val * TOLERANCE / 100 && result >= val - val * TOLERANCE / 100);

This could additionally read "brightness" and assert it is equal to what
was just written (i.e. without the tolerance check).

There are no guarantees that the result read back from
"actual_brightness" would be within the tolerance, in fact it could be
changed by ACPI behind our backs, at least on some platforms... But I
guess this is good enough.

> +}
> +
> +static void test_brightness(int max)
> +{
> +	test_and_verify(0, max);
> +	test_and_verify(max, max);
> +	test_and_verify(max / 2, max);
> +}

A followup could add a test to fade both ways using a loop; can be a
follow-up later on.

Reviewed-by: Jani Nikula <jani.nikula@intel.com>



BR,
Jani.

> +
> +static void test_bad_brightness(int max)
> +{
> +	int val;
> +	/* First write some sane value */
> +	backlight_write(max / 2, "brightness");
> +	/* Writing invalid values should fail and not change the value */
> +	igt_assert(backlight_write(-1, "brightness") < 0);
> +	backlight_read(&val, "brightness");
> +	igt_assert(val == max / 2);
> +	igt_assert(backlight_write(max + 1, "brightness") < 0);
> +	backlight_read(&val, "brightness");
> +	igt_assert(val == max / 2);
> +	igt_assert(backlight_write(INT_MAX, "brightness") < 0);
> +	backlight_read(&val, "brightness");
> +	igt_assert(val == max / 2);
> +}
> +
> +igt_main
> +{
> +	int max, old;
> +
> +	igt_skip_on_simulation();
> +
> +	igt_fixture {
> +		/* Get the max value and skip the whole test if sysfs interface not available */
> +		igt_skip_on(backlight_read(&old, "brightness"));
> +		igt_assert(backlight_read(&max, "max_brightness") > -1);
> +	}
> +
> +	igt_subtest("brightness")
> +		test_brightness(max);
> +	igt_subtest("bad-brightness")
> +		test_bad_brightness(max);
> +
> +	igt_fixture {
> +		/* Restore old brightness */
> +		backlight_write(old, "brightness");
> +	}
> +}
> -- 
> 1.8.3.2
>
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-- 
Jani Nikula, Intel Open Source Technology Center
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