[PATCH 4.0 133/148] drm/radeon: retry dcpd fetch

Greg Kroah-Hartman
2015-06-03T12:24:59Z

From: Alex Deucher <alexander.deucher@amd.com>

commit 0f28d1281b6c54cc98746ae61e44e7f540758ed4 upstream.

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@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/gpu/drm/radeon/atombios_dp.c | 20 +++++++++++---------
1 file changed, 11 insertions(+), 9 deletions(-)

--- a/drivers/gpu/drm/radeon/atombios_dp.c
+++ b/drivers/gpu/drm/radeon/atombios_dp.c
@@ -412,19 +412,21 @@ bool radeon_dp_getdpcd(struct radeon_con
{
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;