This function computes the EDID checksum for a block of EDID data. This function is necessary for Displayport compliance testing as it does not not require the complete EDID checking functionality provided by the DRM layer functions.
Signed-off-by: Todd Previte <[email protected]> --- drivers/gpu/drm/i915/intel_dp.c | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c index 0d11145..f61502e 100644 --- a/drivers/gpu/drm/i915/intel_dp.c +++ b/drivers/gpu/drm/i915/intel_dp.c @@ -3328,6 +3328,29 @@ intel_dp_get_sink_irq(struct intel_dp *intel_dp, u8 *sink_irq_vector) sink_irq_vector, 1) == 1; } +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; + + /* Compute byte total w/o the checksum value*/ + for (i = 0; i < EDID_LENGTH - 2; i++) + byte_total += edid_data[i]; + + DRM_DEBUG_KMS("Displayport: EDID total = %d, EDID checksum = %d\n", byte_total, edid_data[EDID_LENGTH - 1]); + + /* Compute the checksum */ + *edid_checksum = 256 - (byte_total % 256); + + if (*edid_checksum != edid_data[EDID_LENGTH - 1]) { + DRM_DEBUG_KMS("Displayport: Invalid EDID checksum %d, should be %d\n", edid_data[EDID_LENGTH - 1], *edid_checksum); + edid_ok = false; + } + + return edid_ok; +} + /* Displayport compliance testing - Link training */ static uint8_t intel_dp_autotest_link_training(struct intel_dp *intel_dp) -- 1.9.1 _______________________________________________ Intel-gfx mailing list [email protected] http://lists.freedesktop.org/mailman/listinfo/intel-gfx
