Re: [PATCH i-g-t v9 42/49] lib/igt_dp: Create generic helpers for DP information

[Louis Chauvet <louis.chauvet@bootlin.com>]

On 3/17/26 16:55, Kory Maincent wrote:
> On Mon, 16 Mar 2026 17:18:03 +0100
> Louis Chauvet <louis.chauvet@bootlin.com> wrote:
> 
>> With the introduction of unigraf tests, there is no reason to limit the
>> implementation to intel. Create easly extendable generic functions to
>> help supporting multiple GPU.
>>
>> Signed-off-by: Louis Chauvet <louis.chauvet@bootlin.com>
>> ---
>>   lib/igt_dp.c    | 177
>> ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ lib/igt_dp.h    |
>> 30 ++++++++++ lib/meson.build |   1 +
>>   3 files changed, 208 insertions(+)
>>
>> diff --git a/lib/igt_dp.c b/lib/igt_dp.c
>> new file mode 100644
>> index 000000000000..a9c9eb3efede
>> --- /dev/null
>> +++ b/lib/igt_dp.c
>> @@ -0,0 +1,177 @@
>> +// SPDX-License-Identifier: MIT
>> +/*
>> + * Copyright © 2026 Google
>> + *
>> + * Authors:
>> + *   Louis Chauvet <louis.chauvet@bootlin.com>
>> + */
>> +
>> +#include <stdint.h>
>> +
>> +#include "drmtest.h"
>> +#include "i915/i915_dp.h"
>> +#include "igt_core.h"
>> +#include "igt_kms.h"
>> +#include "igt_dp.h"
>> +
>> +/**
>> + * igt_dp_get_current_link_rate: Get current link rate on a display port
>> + * @drm_fd: DRM file descriptor
>> + * @output: igt_output_t object representing the display port
>> + *
>> + * Returns:
>> + * The current link rate in kb/s, or a negative error code on failure.
>> + */
>> +int igt_dp_get_current_link_rate(int drm_fd, igt_output_t *output)
>> +{
>> +	if (is_intel_device(drm_fd))
>> +		/*
>> +		 * i915_dp_get_current_link_rate returns the value in tens
>> of kb/s because
>> +		 * that what the kernel uses. Convert it to kb/s to have a
>> sane unit...
>> +		 */
>> +		return i915_dp_get_current_link_rate(drm_fd, output) * 10;
>> +
>> +	igt_assert_f(false, "Current drm device is not able to report used
>> link rate\n");
>> +	return -EINVAL;
> 
> Just wondering, shouldn't you use igt_skip() here, to skip the specific test
> without exiting the test process?
> Same question for the other igt_assert of this patch.
> 

That a good point. I will change to igt_skip.

>> +}
>> +
>> +/**
>> + * igt_dp_get_current_lane_count: Get current lane count on a display port
>> + * @drm_fd: DRM file descriptor
>> + * @output: igt_output_t object representing the display port
>> + *
>> + * Returns:
>> + * The number of active lanes, or a negative error code on failure.
>> + */
>> +int igt_dp_get_current_lane_count(int drm_fd, igt_output_t *output)
>> +{
>> +	if (is_intel_device(drm_fd))
>> +		return i915_dp_get_current_lane_count(drm_fd, output);
>> +
>> +	igt_assert_f(false, "Current drm device is not able to report used
>> lane count\n");
>> +	return -EINVAL;
>> +}
>> +
>> +/**
>> + * igt_dp_get_max_link_rate: Get maximum link rate on a display port
>> + * @drm_fd:		DRM file descriptor
>> + * @output:		igt_output_t object representing the display port
>> + *
>> + * Returns:
>> + * The maximum link rate in kb/s, or a negative error code on failure.
>> + */
>> +int igt_dp_get_max_link_rate(int drm_fd, igt_output_t *output)
>> +{
>> +	if (is_intel_device(drm_fd))
>> +		/*
>> +		 * i915_dp_get_max_link_rate returns the value in tens of
>> kb/s because
>> +		 * that what the kernel uses. Convert it to kb/s to have a
>> sane unit...
>> +		 */
>> +		return i915_dp_get_max_link_rate(drm_fd, output) * 10;
>> +
>> +	igt_assert_f(false, "Current drm device is not able to report max
>> link rate\n");
>> +	return -EINVAL;
>> +}
>> +
>> +/**
>> + * igt_dp_get_max_supported_rate: Get maximum supported link rate on a
>> display port
>> + * @drm_fd: DRM file descriptor
>> + * @output: igt_output_t object representing the display port
>> + *
>> + * Returns:
>> + * The maximum supported link rate in kb/s, or a negative error code on
>> failure.
>> + */
>> +int igt_dp_get_max_supported_rate(int drm_fd, igt_output_t *output)
>> +{
>> +	if (is_intel_device(drm_fd))
>> +		/*
>> +		 * i915_dp_get_max_supported_rate returns the value in tens
>> of kb/s because
>> +		 * that what the kernel uses. Convert it to kb/s to have a
>> sane unit...
>> +		 */
>> +		return i915_dp_get_max_supported_rate(drm_fd, output) * 10;
>> +
>> +	igt_assert_f(false, "Current drm device is not able to report max
>> link rate\n");
>> +	return -EINVAL;
>> +}
>> +
>> +/**
>> + * igt_dp_get_max_lane_count: Get maximum lane count on a display port
>> + * @drm_fd: DRM file descriptor
>> + * @output: igt_output_t object representing the display port
>> + *
>> + * Returns:
>> + * The maximum number of lanes, or a negative error code on failure.
>> + */
>> +int igt_dp_get_max_lane_count(int drm_fd, igt_output_t *output)
>> +{
>> +	if (is_intel_device(drm_fd))
>> +		return i915_dp_get_max_lane_count(drm_fd, output);
>> +
>> +	igt_assert_f(false, "Current drm device is not able to report max
>> lane count\n");
>> +	return -EINVAL;
>> +}
>> +
>> +/**
>> + * igt_dp_force_link_retrain: Force link retraining on a display port
>> + * @drm_fd:		DRM file descriptor
>> + * @output:		igt_output_t object representing the display port
>> + * @retrain_count:	Number of times to retrain the link
>> + */
>> +void igt_dp_force_link_retrain(int drm_fd, igt_output_t *output, int
>> retrain_count) +{
>> +	if (is_intel_device(drm_fd)) {
>> +		i915_dp_force_link_retrain(drm_fd, output, retrain_count);
>> +		return;
>> +	}
>> +
>> +	igt_assert_f(false, "Current drm device does not support link
>> retraining\n"); +}
>> +
>> +/**
>> + * igt_dp_get_pending_retrain: Get pending link retrain count
>> + * @drm_fd:		DRM file descriptor
>> + * @output:		igt_output_t object representing the display port
>> + *
>> + * Returns:
>> + * The number of pending retrain operations, or a negative error code on
>> failure.
>> + */
>> +int igt_dp_get_pending_retrain(int drm_fd, igt_output_t *output)
>> +{
>> +	if (is_intel_device(drm_fd))
>> +		return i915_dp_get_pending_retrain(drm_fd, output);
>> +
>> +	igt_assert_f(false, "Current drm device does not support pending
>> retrain count checking\n");
>> +	return -EINVAL;
>> +}
>> +
>> +/**
>> + * igt_dp_wait_pending_retrain: Wait for pending link retrain operations to
>> complete
>> + * @drm_fd:		DRM file descriptor
>> + * @output:		igt_output_t object representing the display port
>> + *
>> + * This function waits for any pending link retrain operations to complete
>> on the
>> + * specified display port. It polls the debugfs interface for the pending
>> retrain
>> + * count until it reaches zero, indicating all retrain operations have
>> completed.
>> + */
>> +void igt_dp_wait_pending_retrain(int drm_fd, igt_output_t *output)
>> +{
>> +	double timeout = igt_default_display_detect_timeout();
>> +	struct timespec start, now;
>> +	double elapsed;
>> +
>> +	igt_assert_eq(igt_gettime(&start), 0);
>> +
>> +	while (1) {
>> +		if (!igt_dp_get_pending_retrain(drm_fd, output))
>> +			return;
>> +
>> +		igt_assert_eq(igt_gettime(&now), 0);
>> +		elapsed = (now.tv_sec - start.tv_sec) +
>> +					(now.tv_nsec - start.tv_nsec) / 1e9;
>> +
>> +		if (elapsed >= timeout)
>> +			break;
> 
> igt_time_elapsed() ?

Good catch, I missed it, thanks!

> Regards,