Re: [PATCH 08/13] drm/i915: Support EDID compliance tests with the intel_dp_autotest_edid() function

[Todd Previte <tprevite@gmail.com>]

On 4/14/15 6:35 AM, Paulo Zanoni wrote:
> 2015-04-10 14:42 GMT-03:00 Todd Previte <tprevite@gmail.com>:
>> Updates the EDID compliance test function to perform the EDID read as
>> required by the tests. This read needs to take place in the kernel for
>> reasons of speed and efficiency. The results of the EDID read operations
>> are handed off to userspace so that the userspace app can set the display
>> mode appropriately for the test response.
>>
>> The compliance_test_active flag now appears at the end of the individual
>> test handling functions. This is so that the kernel-side operations can
>> be completed without the risk of interruption from the userspace app
>> that is polling on that flag.
>>
>> V2:
>> - Addressed mailing list feedback
>> - Removed excess debug messages
>> - Removed extraneous comments
>> - Fixed formatting issues (line length > 80)
>> - Updated the debug message in compute_edid_checksum to output hex values
>>    instead of decimal
>> V3:
>> - Addressed more list feedback
>> - Added the test_active flag to the autotest function
>> - Removed test_active flag from handler
>> - Added failsafe check on the compliance test active flag
>>    at the end of the test handler
>> - Fixed checkpatch.pl issues
>> V4:
>> - Removed the checksum computation function and its use as it has been
>>    rendered superfluous by changes to the core DRM EDID functions
>> - Updated to use the raw header corruption detection mechanism
>> - Moved the declaration of the test_data variable here
>> V5:
>> - Update test active flag variable name to match the change in the
>>    first patch of the series.
>> - Relocated the test active flag declaration and initialization
>>    to this patch
>> V6:
>> - Updated to use the new flag for raw EDID header corruption
>> - Removed the extra EDID read from the autotest function
>> - Added the edid_checksum variable to struct intel_dp so that the
>>    autotest function can write it to the sink device
>> - Moved the update to the hpd_pulse function to another patch
>> - Removed extraneous constants
>> V7:
>> - Fixed erroneous placement of the checksum assignment. In some cases
>>    such as when the EDID read fails and is NULL, this causes a NULL ptr
>>    dereference in the kernel. Bad news. Fixed now.
>>
>> Signed-off-by: Todd Previte <tprevite@gmail.com>
>> ---
>>   drivers/gpu/drm/i915/intel_dp.c  | 46 ++++++++++++++++++++++++++++++++++++++++
>>   drivers/gpu/drm/i915/intel_drv.h |  4 ++++
>>   2 files changed, 50 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
>> index ba2da44..3bfdc40 100644
>> --- a/drivers/gpu/drm/i915/intel_dp.c
>> +++ b/drivers/gpu/drm/i915/intel_dp.c
>> @@ -41,6 +41,12 @@
>>
>>   #define DP_LINK_CHECK_TIMEOUT  (10 * 1000)
>>
>> +/* Compliance test status bits  */
>> +#define INTEL_DP_RESOLUTION_SHIFT_MASK 4
>> +#define INTEL_DP_RESOLUTION_PREFERRED  (1 << INTEL_DP_RESOLUTION_SHIFT_MASK)
>> +#define INTEL_DP_RESOLUTION_STANDARD   (2 << INTEL_DP_RESOLUTION_SHIFT_MASK)
>> +#define INTEL_DP_RESOLUTION_FAILSAFE   (3 << INTEL_DP_RESOLUTION_SHIFT_MASK)
>> +
>>   struct dp_link_dpll {
>>          int link_bw;
>>          struct dpll dpll;
>> @@ -3770,6 +3776,35 @@ static uint8_t intel_dp_autotest_video_pattern(struct intel_dp *intel_dp)
>>   static uint8_t intel_dp_autotest_edid(struct intel_dp *intel_dp)
>>   {
>>          uint8_t test_result = DP_TEST_NAK;
>> +       uint32_t ret = 0;
>> +
>> +       if (intel_dp->compliance_edid_invalid ||
>> +           intel_dp->aux.i2c_defer_count > 6) {
>> +               /* Check for NACKs/DEFERs, use failsafe if detected
>> +                *  (DP CTS 1.2 Core Rev 1.1, 4.2.2.4, 4.2.2.5)
>> +                */
>> +               if (intel_dp->aux.i2c_nack_count > 0 ||
>> +                       intel_dp->aux.i2c_defer_count > 0)
>> +                       DRM_DEBUG_KMS("EDID read had %d NACKs, %d DEFERs\n",
>> +                                     intel_dp->aux.i2c_nack_count,
>> +                                     intel_dp->aux.i2c_defer_count);
>> +               intel_dp->compliance_test_data = INTEL_DP_RESOLUTION_FAILSAFE;
> Since this case is expected to happen, shouldn't we return something
> that's not DP_TEST_NAK here?
The spec does not state whether or not we should ACK or NAK this case. 
This value is written to the sink device as the response, so for 
compliance testing purposes, the test device does not appear to care 
whether it's ACK or NAK.
>
> Also, we should try to write the checksum on this case too, shouldn't we?
>
> I see on 4.2.2.6 that the only happy case involves setting the
> failsafe resolution, and optionally sending the checksum.
>
> (sorry for not catching this earlier... I just didn't spot the problem)
Correct. Writing the bad checksum is optional, so I opted not to. Less 
code, less AUX transactions.
>
>> +       } else {
>> +               ret = drm_dp_dpcd_write(&intel_dp->aux,
>> +                                       DP_TEST_EDID_CHECKSUM,
>> +                                       &intel_dp->compliance_edid_checksum, 1);
>> +               if (ret <= 0)
>> +                       DRM_DEBUG_DRIVER("Failed to write EDID checksum\n");
>> +               else
>> +                       DRM_DEBUG_DRIVER("EDID checksum written to sink\n");
>> +
>> +               test_result = DP_TEST_ACK | DP_TEST_EDID_CHECKSUM_WRITE;
>> +               intel_dp->compliance_test_data = INTEL_DP_RESOLUTION_STANDARD;
>> +       }
>> +
>> +       /* Set test active flag here so userspace doesn't interrupt things */
>> +       intel_dp->compliance_test_active = 1;
>> +
>>          return test_result;
>>   }
>>
>> @@ -3785,7 +3820,10 @@ static void intel_dp_handle_test_request(struct intel_dp *intel_dp)
>>          uint8_t rxdata = 0;
>>          int status = 0;
>>
>> +       intel_dp->compliance_test_active = 0;
>>          intel_dp->compliance_test_type = 0;
>> +       intel_dp->compliance_test_data = 0;
>> +
>>          intel_dp->aux.i2c_nack_count = 0;
>>          intel_dp->aux.i2c_defer_count = 0;
>>
>> @@ -3920,11 +3958,19 @@ intel_dp_check_link_status(struct intel_dp *intel_dp)
>>
>>          /* Displayport Link CTS Core 1.2 rev1.1 EDID testing
>>           * 4.2.2.1 - EDID read required for all HPD events
>> +        * Also used for 4.2.2.3, 4.2.2.4 4.2.2.5 and 4.2.2.6
>> +        *   - compliance_edid_invalid flag used for 4.2.2.6
>> +        *   - compliance_edid_checksum used for 4.2.2.3
>>            */
>> +       intel_dp->compliance_edid_invalid = 0;
>>           edid_read = drm_get_edid(connector, adapter);
>>           if (!edid_read || connector->edid_header_corrupt == 1) {
>>                   DRM_DEBUG_DRIVER("Invalid EDID detected\n");
>> +                intel_dp->compliance_edid_invalid = 1;
>> +               intel_dp->compliance_edid_checksum = 0;
>>           }
>> +       else
>> +               intel_dp->compliance_edid_checksum = edid_read->checksum;
>>
>>          /* Try to read the source of the interrupt */
>>          if (intel_dp->dpcd[DP_DPCD_REV] >= 0x11 &&
>> diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
>> index ab811e5..23030a1 100644
>> --- a/drivers/gpu/drm/i915/intel_drv.h
>> +++ b/drivers/gpu/drm/i915/intel_drv.h
>> @@ -650,6 +650,10 @@ struct intel_dp {
>>
>>          /* Displayport compliance testing */
>>          unsigned long compliance_test_type;
>> +       unsigned long compliance_test_data;
>> +       bool compliance_test_active;
>> +       bool compliance_edid_invalid;
>> +       uint8_t compliance_edid_checksum;
>>   };
>>
>>   struct intel_digital_port {
>> --
>> 1.9.1
>>
>> _______________________________________________
>> Intel-gfx mailing list
>> Intel-gfx@lists.freedesktop.org
>> http://lists.freedesktop.org/mailman/listinfo/intel-gfx
>
>

_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
http://lists.freedesktop.org/mailman/listinfo/intel-gfx