From 6bdb2e3821616329125fea108c48fe5fe54aaafc Mon Sep 17 00:00:00 2001
From: Wyatt Wood <wyatt.wood@amd.com>
Date: Mon, 22 Mar 2021 14:02:56 -0400
Subject: [PATCH] drm/amd/display: Add delay in dmub_srv_send_gpint_command
[Why]
Today a parameter is passed to dmub_srv_send_gpint_command
which specifies the max amount of time to wait for the command
to be acked.
This parameter instead specifies the number of times to check if
the command was acked.
We wish to add a lower bound to the timeout, which can be
accomplished by using a delay or a timestamp.
It has been decided to use udelay instead of a timestamp simply
because we don't want to expose a high precision counter if it
doesn't yield large benefits.
[How]
Add udelay(1) between each for loop iteration.
Signed-off-by: Wyatt Wood <wyatt.wood@amd.com>
Reviewed-by: Nicholas Kazlauskas <Nicholas.Kazlauskas@amd.com>
Acked-by: Qingqing Zhuo <qingqing.zhuo@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
---
drivers/gpu/drm/amd/display/dmub/src/dmub_srv.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/gpu/drm/amd/display/dmub/src/dmub_srv.c b/drivers/gpu/drm/amd/display/dmub/src/dmub_srv.c
index e36e89157703..1cbb125b4063 100644
--- a/drivers/gpu/drm/amd/display/dmub/src/dmub_srv.c
+++ b/drivers/gpu/drm/amd/display/dmub/src/dmub_srv.c
@@ -647,6 +647,8 @@ dmub_srv_send_gpint_command(struct dmub_srv *dmub,
dmub->hw_funcs.set_gpint(dmub, reg);
for (i = 0; i < timeout_us; ++i) {
+ udelay(1);
+
if (dmub->hw_funcs.is_gpint_acked(dmub, reg))
return DMUB_STATUS_OK;
}