Retry the dpcd fetch several times. Some eDP panels fail several times before the fetch is successful.
bug: https://bugs.freedesktop.org/show_bug.cgi?id=73530 Signed-off-by: Alex Deucher <alexander.deucher at amd.com> Cc: stable at vger.kernel.org --- drivers/gpu/drm/radeon/atombios_dp.c | 20 +++++++++++--------- 1 file changed, 11 insertions(+), 9 deletions(-) diff --git a/drivers/gpu/drm/radeon/atombios_dp.c b/drivers/gpu/drm/radeon/atombios_dp.c index ed173d3..f81e0d7 100644 --- a/drivers/gpu/drm/radeon/atombios_dp.c +++ b/drivers/gpu/drm/radeon/atombios_dp.c @@ -421,19 +421,21 @@ bool radeon_dp_getdpcd(struct radeon_connector *radeon_connector) { struct radeon_connector_atom_dig *dig_connector = radeon_connector->con_priv; u8 msg[DP_DPCD_SIZE]; - int ret; + int ret, i; - ret = drm_dp_dpcd_read(&radeon_connector->ddc_bus->aux, DP_DPCD_REV, msg, - DP_DPCD_SIZE); - if (ret > 0) { - memcpy(dig_connector->dpcd, msg, DP_DPCD_SIZE); + for (i = 0; i < 7; i++) { + ret = drm_dp_dpcd_read(&radeon_connector->ddc_bus->aux, DP_DPCD_REV, msg, + DP_DPCD_SIZE); + if (ret == DP_DPCD_SIZE) { + memcpy(dig_connector->dpcd, msg, DP_DPCD_SIZE); - DRM_DEBUG_KMS("DPCD: %*ph\n", (int)sizeof(dig_connector->dpcd), - dig_connector->dpcd); + DRM_DEBUG_KMS("DPCD: %*ph\n", (int)sizeof(dig_connector->dpcd), + dig_connector->dpcd); - radeon_dp_probe_oui(radeon_connector); + radeon_dp_probe_oui(radeon_connector); - return true; + return true; + } } dig_connector->dpcd[0] = 0; return false; -- 1.8.3.1
