Re: [PATCH v5 11/36] drm/bridge: analogix_dp: Wait for HPD signal before configuring link

[Archit Taneja]

On Saturday 10 March 2018 03:53 AM, Enric Balletbo i Serra wrote:

From: zain wang 

According to DP spec v1.3 chap 3.5.1.2 Link Training, Link Policy Maker
must first detect that the HPD signal is asserted high by the Downstream
Device before establishing a link with it.


Reviewed-by: Archit Taneja 

Thanks,
Archit



Cc: Stéphane Marchesin 
Signed-off-by: zain wang 
Signed-off-by: Sean Paul 
Signed-off-by: Thierry Escande 
Signed-off-by: Enric Balletbo i Serra 
Tested-by: Marek Szyprowski 
---

  drivers/gpu/drm/bridge/analogix/analogix_dp_core.c | 11 +++
  1 file changed, 11 insertions(+)

diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c 
b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
index c81733b8185e..92fb9a072cb6 100644
--- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
+++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
@@ -1169,6 +1169,17 @@ static int analogix_dp_set_bridge(struct 
analogix_dp_device *dp)
if (ret)
goto out_dp_init;
  
+	/*

+* According to DP spec v1.3 chap 3.5.1.2 Link Training,
+* We should first make sure the HPD signal is asserted high by device
+* when we want to establish a link with it.
+*/
+   ret = analogix_dp_detect_hpd(dp);
+   if (ret) {
+   DRM_ERROR("failed to get hpd single ret = %d\n", ret);
+   goto out_dp_init;
+   }
+
ret = analogix_dp_commit(dp);
if (ret)
goto out_dp_init;

Re: [PATCH v5 11/36] drm/bridge: analogix_dp: Wait for HPD signal before configuring link

[Archit Taneja]

On Saturday 10 March 2018 03:53 AM, Enric Balletbo i Serra wrote:

From: zain wang 

According to DP spec v1.3 chap 3.5.1.2 Link Training, Link Policy Maker
must first detect that the HPD signal is asserted high by the Downstream
Device before establishing a link with it.


Reviewed-by: Archit Taneja 

Thanks,
Archit



Cc: Stéphane Marchesin 
Signed-off-by: zain wang 
Signed-off-by: Sean Paul 
Signed-off-by: Thierry Escande 
Signed-off-by: Enric Balletbo i Serra 
Tested-by: Marek Szyprowski 
---

  drivers/gpu/drm/bridge/analogix/analogix_dp_core.c | 11 +++
  1 file changed, 11 insertions(+)

diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c 
b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
index c81733b8185e..92fb9a072cb6 100644
--- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
+++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
@@ -1169,6 +1169,17 @@ static int analogix_dp_set_bridge(struct 
analogix_dp_device *dp)
if (ret)
goto out_dp_init;
  
+	/*

+* According to DP spec v1.3 chap 3.5.1.2 Link Training,
+* We should first make sure the HPD signal is asserted high by device
+* when we want to establish a link with it.
+*/
+   ret = analogix_dp_detect_hpd(dp);
+   if (ret) {
+   DRM_ERROR("failed to get hpd single ret = %d\n", ret);
+   goto out_dp_init;
+   }
+
ret = analogix_dp_commit(dp);
if (ret)
goto out_dp_init;