Re: [igt-dev] [PATCH V6 i-g-t 2/6] kms_writeback: Add initial writeback tests

["Ser, Simon" <simon.ser@intel.com>]

On Thu, 2019-07-11 at 23:44 -0300, Rodrigo Siqueira wrote:
> On 07/10, Ser, Simon wrote:
> > Hi,
> > 
> > Thanks for the patch! Here are a few comments.
> > 
> > For bonus points, it would be nice to add igt_describe descriptions of
> > each sub-test.
> 
> Hi Simon,
> 
> First of all, thanks for your feedback; I already applied most of your
> suggestions. I just have some inline comments/questions.
>  
> > On Wed, 2019-06-12 at 23:16 -0300, Brian Starkey wrote:
> > > Add tests for the WRITEBACK_PIXEL_FORMATS, WRITEBACK_OUT_FENCE_PTR and
> > > WRITEBACK_FB_ID properties on writeback connectors, ensuring their
> > > behaviour is correct.
> > > 
> > > Signed-off-by: Brian Starkey <brian.starkey@arm.com>
> > > [rebased and updated do_writeback_test() function to address feedback]
> > > Signed-off-by: Liviu Dudau <liviu.dudau@arm.com>
> > > ---
> > >  tests/Makefile.sources |   1 +
> > >  tests/kms_writeback.c  | 314 +++++++++++++++++++++++++++++++++++++++++
> > >  tests/meson.build      |   1 +
> > >  3 files changed, 316 insertions(+)
> > >  create mode 100644 tests/kms_writeback.c
> > > 
> > > diff --git a/tests/Makefile.sources b/tests/Makefile.sources
> > > index 027ed82f..03cc8efa 100644
> > > --- a/tests/Makefile.sources
> > > +++ b/tests/Makefile.sources
> > > @@ -77,6 +77,7 @@ TESTS_progs = \
> > >  	kms_universal_plane \
> > >  	kms_vblank \
> > >  	kms_vrr \
> > > +	kms_writeback \
> > >  	meta_test \
> > >  	perf \
> > >  	perf_pmu \
> > > diff --git a/tests/kms_writeback.c b/tests/kms_writeback.c
> > > new file mode 100644
> > > index 00000000..66ef48a6
> > > --- /dev/null
> > > +++ b/tests/kms_writeback.c
> > > @@ -0,0 +1,314 @@
> > > +/*
> > > + * (C) COPYRIGHT 2017 ARM Limited. All rights reserved.
> > > + *
> > > + * 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.
> > > + *
> > > + */
> > > +
> > > +#include <errno.h>
> > > +#include <stdbool.h>
> > > +#include <stdio.h>
> > > +#include <string.h>
> > > +
> > > +#include "igt.h"
> > > +#include "igt_core.h"
> > > +#include "igt_fb.h"
> > > +
> > > +static drmModePropertyBlobRes *get_writeback_formats_blob(igt_output_t *output)
> > > +{
> > > +	drmModePropertyBlobRes *blob = NULL;
> > > +	uint64_t blob_id;
> > > +	int ret;
> > > +
> > > +	ret = kmstest_get_property(output->display->drm_fd,
> > > +				   output->config.connector->connector_id,
> > > +				   DRM_MODE_OBJECT_CONNECTOR,
> > > +				   igt_connector_prop_names[IGT_CONNECTOR_WRITEBACK_PIXEL_FORMATS],
> > > +				   NULL, &blob_id, NULL);
> > > +	if (ret)
> > > +		blob = drmModeGetPropertyBlob(output->display->drm_fd, blob_id);
> > > +
> > > +	igt_assert(blob);
> > > +
> > > +	return blob;
> > > +}
> > > +
> > > +static bool check_writeback_config(igt_display_t *display, igt_output_t *output)
> > > +{
> > > +	igt_fb_t input_fb, output_fb;
> > > +	igt_plane_t *plane;
> > > +	uint32_t writeback_format = DRM_FORMAT_XRGB8888;
> > > +	uint64_t tiling = igt_fb_mod_to_tiling(0);
> > > +	int width, height, ret;
> > > +	drmModeModeInfo override_mode = {
> > > +		.clock = 25175,
> > > +		.hdisplay = 640,
> > > +		.hsync_start = 656,
> > > +		.hsync_end = 752,
> > > +		.htotal = 800,
> > > +		.hskew = 0,
> > > +		.vdisplay = 480,
> > > +		.vsync_start = 490,
> > > +		.vsync_end = 492,
> > > +		.vtotal = 525,
> > > +		.vscan = 0,
> > > +		.vrefresh = 60,
> > > +		.flags = DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC,
> > > +		.name = {"640x480-60"},
> > > +	};
> > > +	igt_output_override_mode(output, &override_mode);
> > > +
> > > +	width = override_mode.hdisplay;
> > > +	height = override_mode.vdisplay;
> > > +
> > > +	ret = igt_create_fb(display->drm_fd, width, height, DRM_FORMAT_XRGB8888, tiling, &input_fb);
> > > +	igt_assert(ret >= 0);
> > > +
> > > +	ret = igt_create_fb(display->drm_fd, width, height, writeback_format, tiling, &output_fb);
> > > +	igt_assert(ret >= 0);
> > > +
> > > +	plane = igt_output_get_plane_type(output, DRM_PLANE_TYPE_PRIMARY);
> > > +	igt_plane_set_fb(plane, &input_fb);
> > > +	igt_output_set_writeback_fb(output, &output_fb);
> > > +
> > > +	ret = igt_display_try_commit_atomic(display, DRM_MODE_ATOMIC_TEST_ONLY |
> > > +					    DRM_MODE_ATOMIC_ALLOW_MODESET, NULL);
> > 
> > Okay, we're using atomic test-only mode to know if we can perform tests
> > with the writeback output. It's probably fine, but we don't use
> > WRITEBACK_PIXEL_FORMATS, which makes me a little bit sad.
> 
> Sorry, I did not fully understand part. Did you expect to see something
> like the below code before igt_display_try_commit_atomic()?
> 
>  igt_output_set_prop_value(output, WRITEBACK_PIXEL_FORMATS,
>                            DRM_FORMAT_XRGB8888);

Hmm, no, we cannot change the list of writeback formats (it's
immutable).

This comment doesn't require any action, it's just me thinking aloud :P

I'm just thinking that it would be nice to choose our format depending
on the WRITEBACK_PIXEL_FORMATS property. And probably run tests with
each supported format (or, alternatively, choose a random one). That
way we can make sure WRITEBACK_PIXEL_FORMATS isn't broken.

However, this can be left for a later patch.

> > > +	igt_plane_set_fb(plane, NULL);
> > > +	igt_remove_fb(display->drm_fd, &input_fb);
> > > +	igt_remove_fb(display->drm_fd, &output_fb);
> > > +
> > > +	return !ret;
> > > +}
> > > +
> > > +static igt_output_t *kms_writeback_get_output(igt_display_t *display)
> > > +{
> > > +	int i;
> > > +
> > > +	for (i = 0; i < display->n_outputs; i++) {
> > > +		igt_output_t *output = &display->outputs[i];
> > > +		int j;
> > > +
> > > +		if (output->config.connector->connector_type != DRM_MODE_CONNECTOR_WRITEBACK)
> > > +			continue;
> > > +
> > > +		kmstest_force_connector(display->drm_fd, output->config.connector, FORCE_CONNECTOR_ON);
> > 
> > Hmm. Is this really necessary? "Real" userspace won't do this, so I
> > don't think we need to either.
> 
> Hmmm, I have a little experience with userspace; however, I tested
> kms_writeback on top of vkms without this line, and everything worked
> well. If I remove this line, should I also drop the line that force
> connector to FORCE_CONNECTOR_UNSPECIFIED?

I believe so.

> Another question, if FORCE_CONNECTOR_ON is something that userspace
> won't want to do, why do we have it?

We use kmstest_force_connector in injection tests: those pick a
disconnected HDMI connector and trick the kernel into thinking it's
connected. We generally also force an EDID and this is used to emulate
a screen (e.g. a screen that supports audio, 4K or 3D).

This is only meant to be used for testing though, hence "real userspace
shouldn't use it".

> > > +		for (j = 0; j < igt_display_get_n_pipes(display); j++) {
> > > +			igt_output_set_pipe(output, j);
> > > +
> > > +			if (check_writeback_config(display, output)) {
> > > +				igt_debug("Using connector %u:%s on pipe %d\n",
> > > +					  output->config.connector->connector_id,
> > > +					  output->name, j);
> > > +				return output;
> > > +			}
> > 
> > We could probably add an igt_debug statement in case we don't use this
> > writeback output.
> > 
> > > +		}
> > > +
> > > +		/* Restore any connectors we don't use, so we don't trip on them later */
> > > +		kmstest_force_connector(display->drm_fd, output->config.connector, FORCE_CONNECTOR_UNSPECIFIED);
> > > +	}
> > > +
> > > +	return NULL;
> > > +}
> > > +
> > > +static void check_writeback_fb_id(igt_output_t *output)
> > > +{
> > > +	uint64_t check_fb_id;
> > > +
> > > +	check_fb_id = igt_output_get_prop(output, IGT_CONNECTOR_WRITEBACK_FB_ID);
> > > +	igt_assert(check_fb_id == 0);
> > > +}
> > > +
> > > +static int do_writeback_test(igt_output_t *output, uint32_t flags,
> > > +			      uint32_t fb_id, int32_t *out_fence_ptr,
> > > +			      bool ptr_valid)
> > 
> > flags seems to always be set to DRM_MODE_ATOMIC_ALLOW_MODESET. We can
> > probably remove the parameter from this function.
> > 
> > > +{
> > > +	int ret;
> > > +	igt_display_t *display = output->display;
> > > +	struct kmstest_connector_config *config = &output->config;
> > > +
> > > +	igt_output_set_prop_value(output, IGT_CONNECTOR_CRTC_ID, config->crtc->crtc_id);
> > > +	igt_output_set_prop_value(output, IGT_CONNECTOR_WRITEBACK_FB_ID, fb_id);
> > > +	igt_output_set_prop_value(output, IGT_CONNECTOR_WRITEBACK_OUT_FENCE_PTR, (uint64_t)out_fence_ptr);
> > > +
> > > +	if (ptr_valid)
> > > +		*out_fence_ptr = 0;
> > > +
> > > +	ret = igt_display_try_commit_atomic(display, flags, NULL);
> > > +
> > > +	if (ptr_valid)
> > > +		igt_assert(*out_fence_ptr == -1);
> > 
> > I'm confused. Why should this be -1 even if we
> > igt_display_try_commit_atomic succeeds?
> 
> I inspected the drm_mode_atomic_ioctl() function and I noticed that It
> calls complete_signaling() in its turn this function assign -1 to
> out_fence_ptr. Since all of this happens at the end of atomic_commit, I
> believe that we don’t need it. I already removed it.

I think I'm still confused :)

I'm probably missing something. As far as I understand, we are doing an
atomic commit, sometimes with a valid WRITEBACK_FB_ID and
WRITEBACK_OUT_FENCE_PTR. In this case it should start the writeback
process in the kernel and we should get a valid out_fence_ptr?

Why do we always get -1?

> > > +	/* WRITEBACK_FB_ID must always read as zero */
> > > +	check_writeback_fb_id(output);
> > > +
> > > +	return ret;
> > > +}
> > > +
> > > +static void invalid_out_fence(igt_output_t *output, igt_fb_t *valid_fb, igt_fb_t *invalid_fb)
> > > +{
> > > +	int i, ret;
> > > +	int32_t out_fence;
> > > +	struct {
> > > +		uint32_t fb_id;
> > > +		bool ptr_valid;
> > > +		int32_t *out_fence_ptr;
> > > +	} invalid_tests[] = {
> > > +		{
> > > +			/* No output buffer, but the WRITEBACK_OUT_FENCE_PTR set. */
> > > +			.fb_id = 0,
> > > +			.ptr_valid = true,
> > > +			.out_fence_ptr = &out_fence,
> > > +		},
> > > +		{
> > > +			/* Invalid output buffer. */
> > > +			.fb_id = invalid_fb->fb_id,
> > > +			.ptr_valid = true,
> > > +			.out_fence_ptr = &out_fence,
> > > +		},
> > 
> > This doesn't belong in this function (invalid_out_fence), since this
> > checks an invalid framebuffer, not an invalid fence. We should probably
> > move it to writeback_fb_id (and rename that function to test_fb?).
> > 
> > > +		{
> > > +			/* Invalid WRITEBACK_OUT_FENCE_PTR. */
> > > +			.fb_id = valid_fb->fb_id,
> > > +			.ptr_valid = false,
> > > +			.out_fence_ptr = (int32_t *)0x8,
> > > +		},
> > > +	};
> > > +
> > > +	for (i = 0; i < ARRAY_SIZE(invalid_tests); i++) {
> > > +		ret = do_writeback_test(output, DRM_MODE_ATOMIC_ALLOW_MODESET,
> > > +					invalid_tests[i].fb_id,
> > > +					invalid_tests[i].out_fence_ptr,
> > > +					invalid_tests[i].ptr_valid);
> > > +		igt_assert(ret != 0);
> > 
> > Maybe we can check for -ret == EINVAL?
> > 
> > > +	}
> > > +}
> > > +
> > > +static void writeback_fb_id(igt_output_t *output, igt_fb_t *valid_fb, igt_fb_t *invalid_fb)
> > 
> > invalid_fb doesn't seem to be used here. valid_fb seems to be set to
> > the input framebuffer. It's probably not a good idea to use the same FB
> > for input and writeback output.
> > 
> > > +{
> > > +
> > > +	int ret;
> > > +
> > > +	/* Valid output buffer */
> > > +	ret = do_writeback_test(output, DRM_MODE_ATOMIC_ALLOW_MODESET,
> > > +				valid_fb->fb_id, NULL, false);
> > > +	igt_assert(ret == 0);
> > > +
> > > +	/* Invalid object for WRITEBACK_FB_ID */
> > > +	ret = do_writeback_test(output, DRM_MODE_ATOMIC_ALLOW_MODESET,
> > > +				output->id, NULL, false);
> > > +	igt_assert(ret == -EINVAL);
> > > +
> > > +	/* Zero WRITEBACK_FB_ID */
> > > +	ret = do_writeback_test(output, DRM_MODE_ATOMIC_ALLOW_MODESET,
> > > +				0, NULL, false);
> > > +	igt_assert(ret == 0);
> > > +}
> > > +
> > > +igt_main
> > > +{
> > > +	igt_display_t display;
> > > +	igt_output_t *output;
> > > +	igt_plane_t *plane;
> > > +	igt_fb_t input_fb;
> > > +	drmModeModeInfo mode;
> > > +	int ret;
> > > +
> > > +	memset(&display, 0, sizeof(display));
> > > +
> > > +	igt_fixture {
> > > +		display.drm_fd = drm_open_driver_master(DRIVER_ANY);
> > > +		igt_display_require(&display, display.drm_fd);
> > > +
> > > +		kmstest_set_vt_graphics_mode();
> > > +
> > > +		igt_display_require(&display, display.drm_fd);
> > > +
> > > +		igt_require(display.is_atomic);
> > > +
> > > +		output = kms_writeback_get_output(&display);
> > > +		igt_require(output);
> > > +
> > > +		if (output->use_override_mode)
> > > +			memcpy(&mode, &output->override_mode, sizeof(mode));
> > > +		else
> > > +			memcpy(&mode, &output->config.default_mode, sizeof(mode));
> > > +
> > > +		plane = igt_output_get_plane_type(output, DRM_PLANE_TYPE_PRIMARY);
> > > +		igt_require(plane);
> > 
> > Maybe we can assert on this?
> > 
> > > +		ret = igt_create_fb(display.drm_fd, mode.hdisplay,
> > > +				    mode.vdisplay,
> > > +				    DRM_FORMAT_XRGB8888,
> > > +				    igt_fb_mod_to_tiling(0),
> > 
> > This is supposed to take a modifier. DRM_FORMAT_MOD_LINEAR would be
> > better to make this clear.
> > 
> > (Applies to other lines of this patch)
> > 
> > > +				    &input_fb);
> > > +		igt_assert(ret >= 0);
> > > +		igt_plane_set_fb(plane, &input_fb);
> > > +	}
> > > +
> > > +	igt_subtest("writeback-pixel-formats") {
> > > +		drmModePropertyBlobRes *formats_blob = get_writeback_formats_blob(output);
> > 
> > Need to drmModeFreePropertyBlob this.
> > 
> > > +		const char *valid_chars = "0123456 ABCGNRUVXY";
> > > +		unsigned int i;
> > > +		char *c;
> > > +
> > > +		/*
> > > +		 * We don't have a comprehensive list of formats, so just check
> > > +		 * that the blob length is sensible and that it doesn't contain
> > > +		 * any outlandish characters
> > > +		 */
> > > +		igt_assert(!(formats_blob->length % 4));
> > > +		c = formats_blob->data;
> > > +		for (i = 0; i < formats_blob->length; i++)
> > > +			igt_assert_f(strchr(valid_chars, c[i]),
> > > +				     "Unexpected character %c\n", c[i]);
> > 
> > Honestly, I'm not a fan of this check. There's no guarantee that fourcc
> > codes will be made from ASCII characters, in fact some formats already
> > have non-printable chars in them. I don't want to have to update this
> > test when a new fourcc format is added.
> > 
> > We currently don't have a test for IN_FORMATS. If we really want to
> > check formats, we could have a big array of known formats and add a
> > bool is_valid_format(uint32_t fmt) function.
> 
> Agree with you. How about remove this test?

I guess we could always keep the length % 4 test, even if it's just a
sanity test. At least this one won't ever need to be changed.

I don't feel strongly about it.

> Thanks
> Best Regards
> 
> > > +	}
> > > +
> > > +	igt_subtest("writeback-invalid-out-fence") {
> > > +		igt_fb_t invalid_fb;
> > 
> > invalid_output_fb would be a better name IMHO.
> > 
> > > +		ret = igt_create_fb(display.drm_fd, mode.hdisplay / 2,
> > > +				    mode.vdisplay / 2,
> > > +				    DRM_FORMAT_XRGB8888,
> > > +				    igt_fb_mod_to_tiling(0),
> > > +				    &invalid_fb);
> > > +		igt_require(ret > 0);
> > 
> > We should probably use a different variable: ret is signed,
> > igt_create_fb isn't. Also ret doesn't make it clear that the return
> > value is the KMS framebuffer ID.
> > 
> > (Applies to other subtests)
> > 
> > > +		invalid_out_fence(output, &input_fb, &invalid_fb);
> > 
> > (Still not sure why we provide the input FB to this function.)
> > 
> > > +		igt_remove_fb(display.drm_fd, &invalid_fb);
> > > +	}
> > > +
> > > +	igt_subtest("writeback-fb-id") {
> > > +		igt_fb_t output_fb;
> > > +		ret = igt_create_fb(display.drm_fd, mode.hdisplay, mode.vdisplay,
> > > +				    DRM_FORMAT_XRGB8888,
> > > +				    igt_fb_mod_to_tiling(0),
> > > +				    &output_fb);
> > > +		igt_require(ret > 0);
> > > +
> > > +		writeback_fb_id(output, &input_fb, &output_fb);
> > > +
> > > +		igt_remove_fb(display.drm_fd, &output_fb);
> > > +	}
> > > +
> > > +	igt_fixture {
> > > +		igt_remove_fb(display.drm_fd, &input_fb);
> > > +		igt_display_fini(&display);
> > > +	}
> > > +}
> > > diff --git a/tests/meson.build b/tests/meson.build
> > > index f168fbba..9c77cfcd 100644
> > > --- a/tests/meson.build
> > > +++ b/tests/meson.build
> > > @@ -63,6 +63,7 @@ test_progs = [
> > >  	'kms_universal_plane',
> > >  	'kms_vblank',
> > >  	'kms_vrr',
> > > +	'kms_writeback',
> > >  	'meta_test',
> > >  	'panfrost_get_param',
> > >  	'panfrost_gem_new',
> > > _______________________________________________
> > > igt-dev mailing list
> > > igt-dev@lists.freedesktop.org
> > > https://lists.freedesktop.org/mailman/listinfo/igt-dev
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