[Intel-gfx] [PATCH 11/17] drm/i915: Update the EDID automated compliance test function

[Paulo Zanoni]

2014-12-10 21:53 GMT-02:00 Todd Previte <tprevite at 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 are handed
> off to userspace so that the remainder of the test can be conducted there.
>
> 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
>
> Signed-off-by: Todd Previte <tprevite at gmail.com>
> ---
>  drivers/gpu/drm/i915/intel_dp.c | 72 ++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 71 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index b6f5a72..2a13124 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -40,6 +40,13 @@
>
>  #define DP_LINK_CHECK_TIMEOUT  (10 * 1000)
>
> +/* Compliance test status bits  */
> +#define  INTEL_DP_EDID_OK              (0<<0)
> +#define  INTEL_DP_EDID_CORRUPT         (1<<0)
> +#define  INTEL_DP_RESOLUTION_PREFERRED (1<<2)
> +#define  INTEL_DP_RESOLUTION_STANDARD  (1<<3)
> +#define  INTEL_DP_RESOLUTION_FAILSAFE  (1<<4)
> +
>  struct dp_link_dpll {
>         int link_bw;
>         struct dpll dpll;
> @@ -3761,9 +3768,72 @@ static uint8_t intel_dp_autotest_video_pattern(struct intel_dp *intel_dp)
>         return test_result;
>  }
>
> +static bool intel_dp_compute_edid_checksum(uint8_t *edid_data,
> +                                          uint8_t *edid_checksum)
> +{
> +       uint32_t byte_total = 0;
> +       uint8_t i = 0;
> +       bool edid_ok = true;
> +
> +       /* Don't include last byte (the checksum) in the computation */
> +       for (i = 0; i < EDID_LENGTH - 2; i++)

Shouldn't this be "i < EDID_LENGHT - 1"?


> +               byte_total += edid_data[i];
> +
> +       *edid_checksum = 256 - (byte_total % 256);
> +
> +       if (*edid_checksum != edid_data[EDID_LENGTH - 1]) {
> +               DRM_DEBUG_KMS("Invalid EDID checksum %02x, should be %02x\n",
> +                             edid_data[EDID_LENGTH - 40 - 1], *edid_checksum);
> +               edid_ok = false;
> +       }
> +
> +       return edid_ok;
> +}
> +
>  static uint8_t intel_dp_autotest_edid(struct intel_dp *intel_dp)
>  {
> -       uint8_t test_result = DP_TEST_NAK;
> +       struct drm_connector *connector = &intel_dp->attached_connector->base;
> +       struct i2c_adapter *adapter = &intel_dp->aux.ddc;
> +       struct edid *edid_read = NULL;
> +       uint8_t *edid_data = NULL;
> +       uint8_t test_result = DP_TEST_NAK, checksum = 0;
> +       uint32_t ret = 0;
> +
> +       intel_dp->aux.i2c_nack_count = 0;
> +       intel_dp->aux.i2c_defer_count = 0;
> +
> +       edid_read = drm_get_edid(connector, adapter);
> +
> +       if (edid_read == NULL) {
> +               /* 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);

Don't we need to use these _count values somehow, instead of just
printing them in the logs?

Everything else looks fine.

> +               intel_dp->compliance_test_data = INTEL_DP_EDID_CORRUPT |
> +                                                INTEL_DP_RESOLUTION_FAILSAFE;
> +       } else {
> +               edid_data = (uint8_t *) edid_read;
> +
> +               if (intel_dp_compute_edid_checksum(edid_data, &checksum)) {
> +                       ret = drm_dp_dpcd_write(&intel_dp->aux,
> +                                               DP_TEST_EDID_CHECKSUM,
> +                                               &edid_read->checksum, 1);
> +                       test_result = DP_TEST_ACK |
> +                                     DP_TEST_EDID_CHECKSUM_WRITE;
> +                       intel_dp->compliance_test_data =
> +                               INTEL_DP_EDID_OK |
> +                               INTEL_DP_RESOLUTION_PREFERRED;
> +               } else {
> +                       /* Invalid checksum - EDID corruption detection */
> +                       intel_dp->compliance_test_data =
> +                               INTEL_DP_EDID_CORRUPT |
> +                               INTEL_DP_RESOLUTION_FAILSAFE;
> +               }
> +       }
> +
>         return test_result;
>  }
>
> --
> 1.9.1
>
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-- 
Paulo Zanoni