Re: [PATCH 2/2] drm/i915/dp: Validate the compliance test link parameters

[Manasi Navare <manasi.d.navare@intel.com>]

On Fri, Jun 02, 2017 at 11:55:32AM +0300, Jani Nikula wrote:
> On Fri, 02 Jun 2017, Jani Nikula <jani.nikula@linux.intel.com> wrote:
> > On Fri, 02 Jun 2017, Manasi Navare <manasi.d.navare@intel.com> wrote:
> >> Validate the compliance test link parameters when the compliance
> >> test dpcd registers are read. Also validate them in compute_config
> >> before using them since the max values might have been reduced
> >> due to link training fallback.
> >>
> >> Signed-off-by: Manasi Navare <manasi.d.navare@intel.com>
> >> ---
> >>  drivers/gpu/drm/i915/intel_dp.c | 29 +++++++++++++----------------
> >>  1 file changed, 13 insertions(+), 16 deletions(-)
> >>
> >> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> >> index 832786d..cda0f0a 100644
> >> --- a/drivers/gpu/drm/i915/intel_dp.c
> >> +++ b/drivers/gpu/drm/i915/intel_dp.c
> >> @@ -1678,12 +1678,15 @@ intel_dp_compute_config(struct intel_encoder *encoder,
> >>  	if (intel_dp->compliance.test_type == DP_TEST_LINK_TRAINING) {
> >>  		int index;
> >>  
> >> -		index = intel_dp_rate_index(intel_dp->common_rates,
> >> -					    intel_dp->num_common_rates,
> >> -					    intel_dp->compliance.test_link_rate);
> >> -		if (index >= 0)
> >> +		/* Validate the compliance test data */
> 
> Oh, and please do cite the reason for doing this again in the comment. I
> first read the code, didn't get it, until I read the commit message. :)
> 
> BR,
> Jani.
>

Thanks for the review. Will add this reason in the comment.
Will send a new revision with this change and checking index >=0.

Regards
Manasi

 
> 
> >> +		if (intel_dp_link_params_valid(intel_dp, intel_dp->compliance.test_link_rate,
> >> +					       intel_dp->compliance.test_lane_count)) {
> >> +			index = intel_dp_rate_index(intel_dp->common_rates,
> >> +						    intel_dp->num_common_rates,
> >> +						    intel_dp->compliance.test_link_rate);
> >
> > I think you still need to check index >= 0. intel_dp_link_params_valid
> > only checks the boundaries, not that the common rates actually contains
> > the value.
> >
> >>  			min_clock = max_clock = index;
> >> -		min_lane_count = max_lane_count = intel_dp->compliance.test_lane_count;
> >> +			min_lane_count = max_lane_count = intel_dp->compliance.test_lane_count;
> >> +		}
> >>  	}
> >>  	DRM_DEBUG_KMS("DP link computation with max lane count %i "
> >>  		      "max bw %d pixel clock %iKHz\n",
> >> @@ -3961,8 +3964,7 @@ intel_dp_get_sink_irq_esi(struct intel_dp *intel_dp, u8 *sink_irq_vector)
> >>  static uint8_t intel_dp_autotest_link_training(struct intel_dp *intel_dp)
> >>  {
> >>  	int status = 0;
> >> -	int min_lane_count = 1;
> >> -	int link_rate_index, test_link_rate;
> >> +	int test_link_rate;
> >>  	uint8_t test_lane_count, test_link_bw;
> >>  	/* (DP CTS 1.2)
> >>  	 * 4.3.1.11
> >> @@ -3976,10 +3978,6 @@ static uint8_t intel_dp_autotest_link_training(struct intel_dp *intel_dp)
> >>  		return DP_TEST_NAK;
> >>  	}
> >>  	test_lane_count &= DP_MAX_LANE_COUNT_MASK;
> >> -	/* Validate the requested lane count */
> >> -	if (test_lane_count < min_lane_count ||
> >> -	    test_lane_count > intel_dp->max_link_lane_count)
> >> -		return DP_TEST_NAK;
> >>  
> >>  	status = drm_dp_dpcd_readb(&intel_dp->aux, DP_TEST_LINK_RATE,
> >>  				   &test_link_bw);
> >> @@ -3987,12 +3985,11 @@ static uint8_t intel_dp_autotest_link_training(struct intel_dp *intel_dp)
> >>  		DRM_DEBUG_KMS("Link Rate read failed\n");
> >>  		return DP_TEST_NAK;
> >>  	}
> >> -	/* Validate the requested link rate */
> >>  	test_link_rate = drm_dp_bw_code_to_link_rate(test_link_bw);
> >> -	link_rate_index = intel_dp_rate_index(intel_dp->common_rates,
> >> -					      intel_dp->num_common_rates,
> >> -					      test_link_rate);
> >> -	if (link_rate_index < 0)
> >> +
> >> +	/* Validate the requested link rate and lane count */
> >> +	if (!intel_dp_link_params_valid(intel_dp, test_link_rate,
> >> +					test_lane_count))
> >>  		return DP_TEST_NAK;
> >
> > The changes here LGTM.
> >
> >>  
> >>  	intel_dp->compliance.test_lane_count = test_lane_count;
> 
> -- 
> Jani Nikula, Intel Open Source Technology Center
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