[PATCH] drm/i915/dp_link_caps: Validate max link rate

[PATCH] drm/i915/dp_link_caps: Validate max link rate

[tarund18303]

From: tarun-tarun143 <tarund18303@gmail.com>

Validate the maximum link rate against the source-supported rates
before using the maximum link limits to calculate allowed
configurations.

This prevents an unsupported link rate from being accepted as a
maximum link limit.

Signed-off-by: tarun-tarun143 <tarund18303@gmail.com>
---
 drivers/gpu/drm/i915/display/intel_dp_link_caps.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/display/intel_dp_link_caps.c b/drivers/gpu/drm/i915/display/intel_dp_link_caps.c
index 7b6cc6055da8..0934488153bb 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_link_caps.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_link_caps.c
@@ -710,7 +710,10 @@ static bool max_link_limits_valid(struct intel_dp_link_caps *link_caps,
 	    !is_power_of_2(max_link_limits->lane_count))
 		return false;
 
-	/* TODO: Validate max_link_limits->rate against the source supported rates. */
+	if (intel_dp_rate_index(link_caps->dp->source_rates,
+				link_caps->dp->num_source_rates,
+				max_link_limits->rate) < 0)
+		return false;
 
 	intel_dp_link_caps_get_forced_params(link_caps, &forced_params);
 	allowed_configs = calc_allowed_config_filter(link_caps, link_caps->enabled_configs,

base-commit: 73e3f0710014fe6d4ed98cfc02292f6121db7558
-- 
2.43.0

Re: [PATCH] drm/i915/dp_link_caps: Validate max link rate

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] The newly added validation check in `max_link_limits_valid()` breaks existing KUnit tests in `intel_dp_link_test.c` because the mock `intel_dp` environment does not initialize `source_rates`.
--

commit 449b7e18bca4c6d9716f634b5437a3f267bbd539
Author: tarun-tarun143 <tarund18303@gmail.com>

drm/i915/dp_link_caps: Validate max link rate

This commit validates the maximum link rate against the source-supported rates
before using the limits to calculate allowed configurations. This prevents
unsupported link rates from being accepted as a maximum link limit.

> diff --git a/drivers/gpu/drm/i915/display/intel_dp_link_caps.c b/drivers/gpu/drm/i915/display/intel_dp_link_caps.c
> index 7b6cc6055da82..0934488153bbc 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp_link_caps.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp_link_caps.c
> @@ -710,7 +710,10 @@ static bool max_link_limits_valid(struct intel_dp_link_caps *link_caps,
>  	    !is_power_of_2(max_link_limits->lane_count))
>  		return false;
>  
> -	/* TODO: Validate max_link_limits->rate against the source supported rates. */
> +	if (intel_dp_rate_index(link_caps->dp->source_rates,
> +				link_caps->dp->num_source_rates,
> +				max_link_limits->rate) < 0)
> +		return false;

[Severity: Medium]
Does this change cause the KUnit tests in intel_dp_link_test.c to fail?

Looking at the mock environment initialization in intel_dp_link_test_init():

drivers/gpu/drm/i915/display/tests/intel_dp_link_test.c:intel_dp_link_test_init() {
	/* Reset the dev state for each test. */
	memset(&test_ctx.dev, 0, sizeof(test_ctx.dev));
	...
	intel_dp->link.caps = test_ctx.link_caps_ops->init(intel_dp);
}

The mock initialization zeroes the memory but does not populate source_rates 
or num_source_rates, leaving them at 0 or NULL. As a result, 
intel_dp_rate_index() will evaluate to -1 during the tests.

This causes unconditional test failures when setting max limits, for example
in verify_link_caps_for_order():

drivers/gpu/drm/i915/display/tests/intel_dp_link_test.c:verify_link_caps_for_order() {
	...
	KUNIT_ASSERT_TRUE(test, ops->set_max_limits(link_caps, &old_max_limits));
}

Could the mock environment be updated to provide valid source_rates so the
tests can successfully pass this new validation check?

>  
>  	intel_dp_link_caps_get_forced_params(link_caps, &forced_params);
>  	allowed_configs = calc_allowed_config_filter(link_caps, link_caps->enabled_configs,

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260827022035.3442-1-tarund18303@gmail.com?part=1

✗ LGCI.VerificationFailed: failure for drm/i915/dp_link_caps: Validate max link rate

[Patchwork]

== Series Details ==

Series: drm/i915/dp_link_caps: Validate max link rate
URL   : https://patchwork.freedesktop.org/series/172865/
State : failure

== Summary ==

Series author address 'tarund18303@gmail.com' is not on the allowlist, which prevents CI from being automatically triggered.
If you want CI to run for this series, ask Patchwork project owners to click 'retest' on the series in Patchwork.
Exception occurred during validation, bailing out!
Build URL: http://intel-gfx-ci-public.igk.intel.com:8080/job/xe_pw_trigger/1262912/ (on master)