On Thu, Jul 15, 2021 at 12:00 AM Modem, Bhanuprakash
[off-list ref] wrote:

quoted

From: Mark Yacoub <redacted>
Sent: Monday, July 12, 2021 8:27 PM
To: Harry Wentland <harry.wentland@amd.com>
Cc: Varide, Nischal <redacted>; Modem, Bhanuprakash
[off-list ref]; igt-dev@lists.freedesktop.org; Arkadiusz Hiler
[off-list ref]; Sean Paul [off-list ref]; Siqueira, Rodrigo
[off-list ref]
Subject: Re: [igt-dev] [PATCH i-g-t 1/2] tests/kms_dither: New IGT to validate
crtc Dithering

On Mon, Jul 12, 2021 at 9:35 AM Harry Wentland [off-list ref] wrote:

quoted

On 2021-07-08 12:05 p.m., Varide, Nischal wrote:

quoted

-----Original Message-----
From: Modem, Bhanuprakash <redacted>
Sent: Friday, July 9, 2021 2:04 AM
To: igt-dev@lists.freedesktop.org
Cc: Modem, Bhanuprakash <redacted>; Sharma, Swati2

[off-list ref]; Shankar, Uma [off-list ref]; Varide,
Nischal [off-list ref]

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Subject: [PATCH i-g-t 1/2] tests/kms_dither: New IGT to validate crtc

Dithering

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Many of the display devices have color format support less than the color

format of the input data (Ex: 8-bit input data and 6-bit display color depth).
Then the input data will be either truncated or rounded, but this approach
usually causes loss of detail and also produce large banded areas of a single
color that significantly differs from the original image.

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Dithering is a technique used to enhance these colors by creating the

illusion of smoothness by adjusting the nearby pixel color.

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For Eg: Converting 8-bit to 6-bit by modifying the pixel information.

Dithering should be enabled when a panel color depth is lower than the

color depth of the framebuffer.

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Even though feature Dithering is there since legacy, there is no specific

IGT for this. This patch will create New IGT for Dithering.

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And below is the truth table for CRTC Dithering.

|----------------|---------|-------------|
|  Frame buffer  |  Panel  |  Dithering  |
|----------------|---------|-------------|
|      8 BPC     |  6 BPC  |     Yes     |
|----------------|---------|-------------|
|      8 BPC     |  8 BPC  |     No      |
|----------------|---------|-------------|
|      8 BPC     | 10 BPC  |     No      |
|----------------|---------|-------------|
|     10 BPC     |  6 BPC  |     Yes     |
|----------------|---------|-------------|
|     10 BPC     |  8 BPC  |     Yes     |
|----------------|---------|-------------|
|     10 BPC     | 10 BPC  |     No      |
|----------------|---------|-------------|
|     16 BPC     |  6 BPC  |     Yes     |
|----------------|---------|-------------|
|     16 BPC     |  8 BPC  |     Yes     |
|----------------|---------|-------------|
|     16 BPC     | 10 BPC  |     Yes     |
|----------------|---------|-------------|

As i915 enables dithering for 6 bpc panels only, we need to limit the

execution to 6 & 8 bpc panels (Negative testing) only.

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Cc: Swati Sharma <redacted>
Cc: Uma Shankar <redacted>
Cc: Nischal Varide <redacted>
Signed-off-by: Bhanuprakash Modem <redacted>
Reviewed-by: Nischal Varide <redacted>
---
 tests/kms_dither.c | 253 +++++++++++++++++++++++++++++++++++++++++++++
 tests/meson.build  |   1 +
 2 files changed, 254 insertions(+)
 create mode 100644 tests/kms_dither.c

diff --git a/tests/kms_dither.c b/tests/kms_dither.c new file mode 100644

index 0000000000..0e0c61dea2

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--- /dev/null
+++ b/tests/kms_dither.c

@@ -0,0 +1,253 @@
+/*
+ * Copyright © 2020 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 COPYRIGHT HOLDER(S) OR AUTHOR(S) 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.
+ *
+ * Authors:
+ *     Bhanuprakash Modem <bhanuprakash.modem@intel.com>
+ *
+ */
+
+#include "igt.h"
+#include <fcntl.h>
+#include <termios.h>
+#include <unistd.h>
+
+IGT_TEST_DESCRIPTION("Test Dithering block status");
+
+/* Connector BPC */
+#define IGT_CONNECTOR_BPC_6          6
+#define IGT_CONNECTOR_BPC_8          8
+#define IGT_CONNECTOR_BPC_10         10
+#define IGT_CONNECTOR_BPC_12         12
+
+/* Framebuffer BPC */
+#define IGT_FRAME_BUFFER_BPC_8               8
+#define IGT_FRAME_BUFFER_BPC_10              10
+#define IGT_FRAME_BUFFER_BPC_16              16
+
+/* Common test data. */
+typedef struct data {
+     igt_display_t display;
+     igt_plane_t *primary;
+     igt_output_t *output;
+     igt_pipe_t *pipe;
+     drmModeModeInfo *mode;
+     enum pipe pipe_id;
+     int drm_fd;
+     igt_fb_t fb;
+} data_t;
+
+typedef struct {
+     unsigned int bpc;
+     unsigned int dither;
+} dither_status_t;
+
+/* Prepare test data. */
+static void prepare_test(data_t *data, igt_output_t *output, enum pipe
+pipe) {
+     igt_display_t *display = &data->display;
+
+     data->pipe_id = pipe;
+     data->pipe = &data->display.pipes[data->pipe_id];
+     igt_assert(data->pipe);
+
+     igt_display_reset(display);
+
+     data->output = output;
+     igt_assert(data->output);
+
+     data->mode = igt_output_get_mode(data->output);
+     igt_assert(data->mode);
+
+     data->primary =
+             igt_pipe_get_plane_type(data->pipe, DRM_PLANE_TYPE_PRIMARY);
+
+     igt_output_set_pipe(data->output, data->pipe_id); }
+
+/* Returns the current state of dithering from the crtc debugfs. */
+static dither_status_t get_dither_state(data_t *data) {
+     char buf[512], tmp[5];
+     char *start_loc;
+     int dir, res;
+     dither_status_t status;
+
+     dir = igt_debugfs_dir(data->drm_fd);
+     igt_assert(dir >= 0);
+
+     res = igt_debugfs_simple_read(dir, "i915_display_info", buf,

sizeof(buf));

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This seems to be an i915-specific test. Do those belong in the kms_

namespace?

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Could this be made into a generic test?

Harry

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+     igt_require(res > 0);
+     close(dir);
+
+     igt_assert(start_loc = strstr(buf, ", bpp="));
+     igt_assert_eq(sscanf(start_loc, ", bpp=%u", &status.bpc), 1);
+     status.bpc /= 3;
+
+     igt_assert(start_loc = strstr(buf, ", dither="));
+     igt_assert_eq(sscanf(start_loc, ", dither=%s", tmp), 1);
+     status.dither = !strcmp(tmp, "yes,");
+
+     return status;
+}
+
+static void test_dithering(data_t *data, enum pipe pipe,
+                        igt_output_t *output,
+                        int fb_bpc, int fb_format,
+                        int output_bpc)
+{
+     igt_display_t *display = &data->display;
+     dither_status_t status;
+     int bpc;
+
+     igt_info("Dithering test execution on %s PIPE_%s\n",
+                     output->name, kmstest_pipe_name(pipe));
+     prepare_test(data, output, pipe);
+
+     igt_assert(igt_create_fb(data->drm_fd, data->mode->hdisplay,
+                              data->mode->vdisplay, fb_format,
+                              LOCAL_DRM_FORMAT_MOD_NONE, &data->fb));
+     igt_plane_set_fb(data->primary, &data->fb);
+     igt_plane_set_size(data->primary, data->mode->hdisplay,
+data->mode->vdisplay);
+
+     bpc = igt_output_get_prop(output, IGT_CONNECTOR_MAX_BPC);
+     igt_output_set_prop_value(data->output, IGT_CONNECTOR_MAX_BPC,

output_bpc);

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+     igt_display_commit2(display, display->is_atomic ? COMMIT_ATOMIC :
+COMMIT_LEGACY);
+
+     /*
+      * Check the status of Dithering block:
+      *
+      * Preserve the result & compute later (after clean-up).
+      * If fb_bpc is greater than output_bpc, Dithering should be enabled
+      * Else disabled
+      */
+     status = get_dither_state(data);
+
+     igt_debug("FB BPC:%d, Panel BPC:%d, Pipe BPC:%d, Expected Dither:%s,

Actual result:%s\n",

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+               fb_bpc, output_bpc, status.bpc,
+               (fb_bpc > output_bpc) ? "Enable": "Disable",
+               status.dither ? "Enable": "Disable");
+
+       /*
+     * We must update the Connector max_bpc property back
+     * Otherwise, previously updated value will stay forever and
+     * may cause the failures for next/other subtests.
+     */
+     igt_output_set_prop_value(data->output, IGT_CONNECTOR_MAX_BPC, bpc);
+     igt_plane_set_fb(data->primary, NULL);
+     igt_output_set_pipe(output, PIPE_NONE);
+     igt_display_commit2(display, display->is_atomic ? COMMIT_ATOMIC :

COMMIT_LEGACY);

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+     igt_remove_fb(data->drm_fd, &data->fb);
+
+     /* Check if crtc bpc is updated with requested one. */
+     igt_require_f((status.bpc == output_bpc),
+                     "%s can support max %u-bpc, but requested %d-bpc\n",
+                             output->name, status.bpc, output_bpc);
+
+     /* Compute the result. */
+     if (fb_bpc > output_bpc)
+             igt_assert_f(status.dither, "(fb_%dbpc > output_%dbpc):

Dither should be enabled\n",

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+                             fb_bpc, output_bpc);
+     else
+             igt_assert_f(!status.dither, "(fb_%dbpc <= output_%dbpc):

Dither should be disabled\n",

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+                             fb_bpc, output_bpc);
+
+     return;
+}
+
+/* Returns true if an output supports max bpc property & max_bpc >=
+requested. */ static bool is_supported(igt_output_t *output, int bpc) {
+        return igt_output_has_prop(output, IGT_CONNECTOR_MAX_BPC) &&
+            igt_output_get_prop(output, IGT_CONNECTOR_MAX_BPC); }
+
+static void
+run_dither_test(data_t *data, int fb_bpc, int fb_format, int
+output_bpc) {
+     igt_output_t *output;
+     igt_display_t *display = &data->display;
+
+     for_each_connected_output(display, output) {
+             enum pipe pipe;
+             drmModeConnector *connector = output->config.connector;
+
+             if (!is_supported(output, output_bpc))
+                     continue;
+
+             /* HDMI won't support 6 BPC */
+             if (output_bpc == IGT_CONNECTOR_BPC_6 &&
+                (connector->connector_type == DRM_MODE_CONNECTOR_HDMIA ||
+                 connector->connector_type == DRM_MODE_CONNECTOR_HDMIB))
+                     continue;
+
+             for_each_pipe(display, pipe) {
+                     if (igt_pipe_connector_valid(pipe, output)) {
+                             igt_dynamic_f("%s-pipe-%s", output->name,

kmstest_pipe_name(pipe))

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+                                     test_dithering(data, pipe, output,

fb_bpc,

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+                                                     fb_format,

output_bpc);

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+
+                             /* One pipe is enough */
+                             break;
+                     }
+             }
+     }
+}
+
+igt_main
+{
+     struct {
+             int fb_bpc;
+             int format;
+             int output_bpc;
+     } tests[] = {
+             { IGT_FRAME_BUFFER_BPC_8, DRM_FORMAT_XRGB8888,

IGT_CONNECTOR_BPC_6 },

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+             { IGT_FRAME_BUFFER_BPC_8, DRM_FORMAT_XRGB8888,

IGT_CONNECTOR_BPC_8 },

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+     };
+     int i;
+     data_t data = { 0 };
+
+     igt_fixture {
+             data.drm_fd = drm_open_driver_master(DRIVER_INTEL);

I agree with Harry.
For context: KMS tests on IGT are officially supported on multiple
SoCs and there is an active development on it along with Intel's.
With that being said, KMS tests are meant to be generic. I understand
if sometime you need to test little things specific for intel so we
use igt_require_[intel | otherdriver], but if the whole test is intel
specific, it doesn't make sense to be part of kms, the best place for
it would be tests/i915.
So basically, we shouldn't have any `
drm_open_driver_master(DRIVER_INTEL);` in any kms_* tests.
Alternatively, this test can be made generic and everyone is happy :))

Agreed, Dithering is not intel specific. As this test is already merged,

`> for now maybe we can add a check intel_require(intel) in igt_fixture, and

start working to make this test generic.

Does this make sense?

Hey Bhanu,
So I ran the test on a Zork (amdgpu) device and it's pretty gracefully
handled. The first subtest skips due to `eDP-1 don't support 6-bpc`
and the second one is pretty expected as you try to open
`i915_display_info` but it skips at `igt_require(res > 0);`.
Basically everything is gracefully handled if you do
`drm_open_driver_master(DRIVER_ANY);` and should be quite easy to
extend it to other platforms when needed.
I don't mind uploading the change so let me know :))

- Bhanu

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+             kmstest_set_vt_graphics_mode();
+
+             igt_display_require(&data.display, data.drm_fd);
+             igt_display_require_output(&data.display);
+     }
+
+     for (i = 0; i < ARRAY_SIZE(tests); i++) {
+             igt_describe_f("Framebuffer BPC:%d, Panel BPC:%d, Expected

Dither:%s\n",

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+                            tests[i].fb_bpc, tests[i].output_bpc,
+                            (tests[i].fb_bpc > tests[i].output_bpc) ?
+                                                     "Enable":

"Disable");

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+
+             igt_subtest_with_dynamic_f("FB-%dBPC-Vs-Panel-%dBPC",
+                             tests[i].fb_bpc, tests[i].output_bpc)
+                     run_dither_test(&data,
+                                     tests[i].fb_bpc,
+                                     tests[i].format,
+                                     tests[i].output_bpc);
+     }
+
+     igt_fixture {
+             igt_display_fini(&data.display);
+     }
+}

diff --git a/tests/meson.build b/tests/meson.build index

01911c4579..d3de40be07 100644

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--- a/tests/meson.build
+++ b/tests/meson.build

@@ -29,6 +29,7 @@ test_progs = [
      'kms_cursor_crc',
      'kms_cursor_edge_walk',
      'kms_cursor_legacy',
+     'kms_dither',
      'kms_dp_aux_dev',
      'kms_dp_dsc',
      'kms_dp_tiled_display',
--

2.20.1

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