[PATCH 5.10 090/717] drm/msm/dp: skip checking LINK_STATUS_UPDATED bit

Greg Kroah-Hartman
2020-12-28T15:18:11Z

From: Kuogee Hsieh <khsieh@codeaurora.org>

[ Upstream commit ea530388e64bd584645f2d89e40ca7dffade8eff ]

Some dongle will not clear LINK_STATUS_UPDATED bit after
DPCD read which cause link training failed. This patch
just read 6 bytes of DPCD link status from sink and return
without checking LINK_STATUS_UPDATED bit.
Only 8 bits are used to represent link rate at sinker DPCD.
The really link rate is 2.7Mb times the 8 bits value.
For example, 0x0A at DPCD is equal to 2.7Gb (10 * 2.7Mb).
This patch also convert 8 bits value of DPCD to really link
rate to fix worng link rate error during phy compliance test.

Fixes: 6625e2637d93 ("drm/msm/dp: DisplayPort PHY compliance tests fixup")
Signed-off-by: Kuogee Hsieh <khsieh@codeaurora.org>
Signed-off-by: Rob Clark <robdclark@chromium.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/gpu/drm/msm/dp/dp_ctrl.c | 20 ++++++--------------
drivers/gpu/drm/msm/dp/dp_link.c | 29 ++++++++++++++---------------
2 files changed, 20 insertions(+), 29 deletions(-)

diff --git a/drivers/gpu/drm/msm/dp/dp_ctrl.c b/drivers/gpu/drm/msm/dp/dp_ctrl.c
index cee161c8ecc67..c83a1650437da 100644
--- a/drivers/gpu/drm/msm/dp/dp_ctrl.c
+++ b/drivers/gpu/drm/msm/dp/dp_ctrl.c
@@ -1061,23 +1061,15 @@ static bool dp_ctrl_train_pattern_set(struct dp_ctrl_private *ctrl,
static int dp_ctrl_read_link_status(struct dp_ctrl_private *ctrl,
u8 *link_status)
{
- int len = 0;
- u32 const offset = DP_LANE_ALIGN_STATUS_UPDATED - DP_LANE0_1_STATUS;
- u32 link_status_read_max_retries = 100;
-
- while (--link_status_read_max_retries) {
- len = drm_dp_dpcd_read_link_status(ctrl->aux,
- link_status);
- if (len != DP_LINK_STATUS_SIZE) {
- DRM_ERROR("DP link status read failed, err: %d\n", len);
- return len;
- }
+ int ret = 0, len;

- if (!(link_status[offset] & DP_LINK_STATUS_UPDATED))
- return 0;
+ len = drm_dp_dpcd_read_link_status(ctrl->aux, link_status);
+ if (len != DP_LINK_STATUS_SIZE) {
+ DRM_ERROR("DP link status read failed, err: %d\n", len);
+ ret = -EINVAL;
}

- return -ETIMEDOUT;
+ return ret;
}

static int dp_ctrl_link_train_1(struct dp_ctrl_private *ctrl,
diff --git a/drivers/gpu/drm/msm/dp/dp_link.c b/drivers/gpu/drm/msm/dp/dp_link.c
index 49d7fad36fc4e..be986da78c4a5 100644
--- a/drivers/gpu/drm/msm/dp/dp_link.c
+++ b/drivers/gpu/drm/msm/dp/dp_link.c
@@ -773,7 +773,8 @@ static int dp_link_process_link_training_request(struct dp_link_private *link)
link->request.test_lane_count);

link->dp_link.link_params.num_lanes = link->request.test_lane_count;
- link->dp_link.link_params.rate = link->request.test_link_rate;
+ link->dp_link.link_params.rate =
+ drm_dp_bw_code_to_link_rate(link->request.test_link_rate);

return 0;
}
@@ -943,22 +944,20 @@ static u8 get_link_status(const u8 link_status[DP_LINK_STATUS_SIZE], int r)
*/
static int dp_link_process_link_status_update(struct dp_link_private *link)
{
- if (!(get_link_status(link->link_status,
- DP_LANE_ALIGN_STATUS_UPDATED) &
- DP_LINK_STATUS_UPDATED) ||
- (drm_dp_clock_recovery_ok(link->link_status,
- link->dp_link.link_params.num_lanes) &&
- drm_dp_channel_eq_ok(link->link_status,
- link->dp_link.link_params.num_lanes)))
- return -EINVAL;
+ bool channel_eq_done = drm_dp_channel_eq_ok(link->link_status,
+ link->dp_link.link_params.num_lanes);

- DRM_DEBUG_DP("channel_eq_done = %d, clock_recovery_done = %d\n",
- drm_dp_clock_recovery_ok(link->link_status,
- link->dp_link.link_params.num_lanes),
- drm_dp_clock_recovery_ok(link->link_status,
- link->dp_link.link_params.num_lanes));
+ bool clock_recovery_done = drm_dp_clock_recovery_ok(link->link_status,
+ link->dp_link.link_params.num_lanes);

- return 0;
+ DRM_DEBUG_DP("channel_eq_done = %d, clock_recovery_done = %d\n",
+ channel_eq_done, clock_recovery_done);
+
+ if (channel_eq_done && clock_recovery_done)
+ return -EINVAL;
+
+
+ return 0;
}

/**
--
2.27.0