[PATCH v2 3/3] drm/msm/dp: check main link status before start aux read

[Kuogee Hsieh]

Make sure main link is in connection state before start aux
read/write operation to avoid unnecessary long delay due to
main link had been unplugged.

Signed-off-by: Kuogee Hsieh <khs...@codeaurora.org>
---
 drivers/gpu/drm/msm/dp/dp_aux.c  |  5 +++++
 drivers/gpu/drm/msm/dp/dp_link.c | 20 +++++++++++++++-----
 2 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/msm/dp/dp_aux.c b/drivers/gpu/drm/msm/dp/dp_aux.c
index 7c22bfe..fae3806 100644
--- a/drivers/gpu/drm/msm/dp/dp_aux.c
+++ b/drivers/gpu/drm/msm/dp/dp_aux.c
@@ -343,6 +343,11 @@ static ssize_t dp_aux_transfer(struct drm_dp_aux *dp_aux,
 
        mutex_lock(&aux->mutex);
 
+       if (!dp_catalog_link_is_connected(aux->catalog)) {
+               ret = -ETIMEDOUT;
+               goto unlock_exit;
+       }
+
        aux->native = msg->request & (DP_AUX_NATIVE_WRITE & DP_AUX_NATIVE_READ);
 
        /* Ignore address only message */
diff --git a/drivers/gpu/drm/msm/dp/dp_link.c b/drivers/gpu/drm/msm/dp/dp_link.c
index be986da..d35b18e 100644
--- a/drivers/gpu/drm/msm/dp/dp_link.c
+++ b/drivers/gpu/drm/msm/dp/dp_link.c
@@ -737,18 +737,25 @@ static int dp_link_parse_sink_count(struct dp_link 
*dp_link)
        return 0;
 }
 
-static void dp_link_parse_sink_status_field(struct dp_link_private *link)
+static int dp_link_parse_sink_status_field(struct dp_link_private *link)
 {
        int len = 0;
 
        link->prev_sink_count = link->dp_link.sink_count;
-       dp_link_parse_sink_count(&link->dp_link);
+       len = dp_link_parse_sink_count(&link->dp_link);
+       if (len < 0) {
+               DRM_ERROR("DP lparse sink count failed\n");
+               return len;
+       }
 
        len = drm_dp_dpcd_read_link_status(link->aux,
                link->link_status);
-       if (len < DP_LINK_STATUS_SIZE)
+       if (len < DP_LINK_STATUS_SIZE) {
                DRM_ERROR("DP link status read failed\n");
-       dp_link_parse_request(link);
+               return len;
+       }
+
+       return dp_link_parse_request(link);
 }
 
 /**
@@ -1032,7 +1039,10 @@ int dp_link_process_request(struct dp_link *dp_link)
 
        dp_link_reset_data(link);
 
-       dp_link_parse_sink_status_field(link);
+       ret = dp_link_parse_sink_status_field(link);
+       if (ret) {
+               return ret;
+       }
 
        if (link->request.test_requested == DP_TEST_LINK_EDID_READ) {
                dp_link->sink_request |= DP_TEST_LINK_EDID_READ;
-- 
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