[PATCH AUTOSEL 6.8 07/28] thunderbolt: Calculate DisplayPort tunnel bandwidth after DPRX capabilities read

Sasha Levin
2024-04-03T17:17:10Z

From: Gil Fine <gil.fine@linux.intel.com>

[ Upstream commit ccd845021147dc8257a05ed8f5a7f9c61a9101e3 ]

According to USB4 Connection Manager guide, after DisplayPort tunnel was
setup, the DPRX capabilities read is performed by the DPTX. According to
VESA spec, this shall be completed within 5 seconds after the DisplayPort
tunnel was setup. Hence, if the bit: DPRX Capabilities Read Done, was
not set to '1' by this time, we timeout and fail calculating DisplayPort
tunnel consumed bandwidth.

Signed-off-by: Gil Fine <gil.fine@linux.intel.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/thunderbolt/tunnel.c | 16 ++++++----------
1 file changed, 6 insertions(+), 10 deletions(-)

diff --git a/drivers/thunderbolt/tunnel.c b/drivers/thunderbolt/tunnel.c
index 6fffb2c82d3d1..4f09216b70f90 100644
--- a/drivers/thunderbolt/tunnel.c
+++ b/drivers/thunderbolt/tunnel.c
@@ -1196,17 +1196,13 @@ static int tb_dp_consumed_bandwidth(struct tb_tunnel *tunnel, int *consumed_up,
/*
* Then see if the DPRX negotiation is ready and if yes
* return that bandwidth (it may be smaller than the
- * reduced one). Otherwise return the remote (possibly
- * reduced) caps.
+ * reduced one). According to VESA spec, the DPRX
+ * negotiation shall compete in 5 seconds after tunnel
+ * established. We give it 100ms extra just in case.
*/
- ret = tb_dp_wait_dprx(tunnel, 150);
- if (ret) {
- if (ret == -ETIMEDOUT)
- ret = tb_dp_read_cap(tunnel, DP_REMOTE_CAP,
- &rate, &lanes);
- if (ret)
- return ret;
- }
+ ret = tb_dp_wait_dprx(tunnel, 5100);
+ if (ret)
+ return ret;
ret = tb_dp_read_cap(tunnel, DP_COMMON_CAP, &rate, &lanes);
if (ret)
return ret;
--
2.43.0