From: Gil Fine <gil.fine@xxxxxxxxxxxxxxx>
In case of the link is brought up as asymmetric (due to hardware preference), we
honor that and don't transition it to symmetric, unless a router with symmetric
link got plugged below, in the topology (and a bandwidth allows transition to
symmetric).
Signed-off-by: Gil Fine <gil.fine@xxxxxxxxxxxxxxx>
Signed-off-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
---
drivers/thunderbolt/switch.c | 13 +++++++++++++
drivers/thunderbolt/tb.c | 28 +++++++++++++++++++++-------
drivers/thunderbolt/tb.h | 2 ++
3 files changed, 36 insertions(+), 7 deletions(-)
diff --git a/drivers/thunderbolt/switch.c b/drivers/thunderbolt/switch.c
index dbab551ac7b3..900114ba4371 100644
--- a/drivers/thunderbolt/switch.c
+++ b/drivers/thunderbolt/switch.c
@@ -2773,6 +2773,19 @@ static void tb_switch_link_init(struct tb_switch *sw)
if (down->dual_link_port)
down->dual_link_port->bonded = bonded;
tb_port_update_credits(down);
+
+ if (tb_port_get_link_generation(up) < 4)
+ return;
+
+ /*
+ * Set the Gen 4 preferred link width. This is what the router
+ * prefers when the link is brought up. If the router does not
+ * support asymmetric link configuration, this also will be set
+ * to TB_LINK_WIDTH_DUAL.
+ */
+ sw->preferred_link_width = sw->link_width;
+ tb_sw_dbg(sw, "preferred link width %s\n",
+ tb_width_name(sw->preferred_link_width));
}
/**
diff --git a/drivers/thunderbolt/tb.c b/drivers/thunderbolt/tb.c
index 0a32e7ec4dc0..846d2813bb1a 100644
--- a/drivers/thunderbolt/tb.c
+++ b/drivers/thunderbolt/tb.c
@@ -1183,14 +1183,15 @@ static int tb_configure_asym(struct tb *tb, struct tb_port *src_port,
* @dst_port: Destination adapter
* @requested_up: New lower bandwidth request upstream (Mb/s)
* @requested_down: New lower bandwidth request downstream (Mb/s)
+ * @keep_asym: Keep asymmetric link if preferred
*
* Goes over each link from @src_port to @dst_port and tries to
* transition the link to symmetric if the currently consumed bandwidth
- * allows.
+ * allows and link asymmetric preference is ignored (if @keep_asym is %false).
*/
static int tb_configure_sym(struct tb *tb, struct tb_port *src_port,
struct tb_port *dst_port, int requested_up,
- int requested_down)
+ int requested_down, bool keep_asym)
{
bool clx = false, clx_disabled = false, downstream;
struct tb_switch *sw;
@@ -1239,6 +1240,19 @@ static int tb_configure_sym(struct tb *tb, struct tb_port *src_port,
if (up->sw->link_width == TB_LINK_WIDTH_DUAL)
continue;
+ /*
+ * Here consumed < threshold so we can transition the
+ * link to symmetric.
+ *
+ * However, if the router prefers asymmetric link we
+ * honor that (unless @keep_asym is %false).
+ */
+ if (keep_asym &&
+ up->sw->preferred_link_width > TB_LINK_WIDTH_DUAL) {
+ tb_sw_dbg(up->sw, "keeping preferred asymmetric link\n");
+ continue;
+ }
+
/* Disable CL states before doing any transitions */
if (!clx_disabled) {
clx = tb_disable_clx(sw);
@@ -1292,7 +1306,7 @@ static void tb_configure_link(struct tb_port *down, struct tb_port *up,
struct tb_port *host_port;
host_port = tb_port_at(tb_route(sw), tb->root_switch);
- tb_configure_sym(tb, host_port, up, 0, 0);
+ tb_configure_sym(tb, host_port, up, 0, 0, false);
}
/* Set the link configured */
@@ -1477,7 +1491,7 @@ static void tb_deactivate_and_free_tunnel(struct tb_tunnel *tunnel)
* If bandwidth on a link is < asym_threshold
* transition the link to symmetric.
*/
- tb_configure_sym(tb, src_port, dst_port, 0, 0);
+ tb_configure_sym(tb, src_port, dst_port, 0, 0, true);
/* Now we can allow the domain to runtime suspend again */
pm_runtime_mark_last_busy(&dst_port->sw->dev);
pm_runtime_put_autosuspend(&dst_port->sw->dev);
@@ -2299,7 +2313,7 @@ static int tb_alloc_dp_bandwidth(struct tb_tunnel *tunnel, int *requested_up,
* If bandwidth on a link is < asym_threshold transition
* the link to symmetric.
*/
- tb_configure_sym(tb, in, out, *requested_up, *requested_down);
+ tb_configure_sym(tb, in, out, *requested_up, *requested_down, true);
/*
* If requested bandwidth is less or equal than what is
* currently allocated to that tunnel we simply change
@@ -2342,7 +2356,7 @@ static int tb_alloc_dp_bandwidth(struct tb_tunnel *tunnel, int *requested_up,
ret = tb_configure_asym(tb, in, out, *requested_up,
*requested_down);
if (ret) {
- tb_configure_sym(tb, in, out, 0, 0);
+ tb_configure_sym(tb, in, out, 0, 0, true);
return ret;
}
@@ -2350,7 +2364,7 @@ static int tb_alloc_dp_bandwidth(struct tb_tunnel *tunnel, int *requested_up,
requested_down);
if (ret) {
tb_tunnel_warn(tunnel, "failed to allocate bandwidth\n");
- tb_configure_sym(tb, in, out, 0, 0);
+ tb_configure_sym(tb, in, out, 0, 0, true);
}
} else {
ret = -ENOBUFS;
diff --git a/drivers/thunderbolt/tb.h b/drivers/thunderbolt/tb.h
index 1760c21e5b12..997c5a536905 100644
--- a/drivers/thunderbolt/tb.h
+++ b/drivers/thunderbolt/tb.h
@@ -125,6 +125,7 @@ struct tb_switch_tmu {
* @device_name: Name of the device (or %NULL if not known)
* @link_speed: Speed of the link in Gb/s
* @link_width: Width of the upstream facing link
+ * @preferred_link_width: Router preferred link width (only set for Gen 4 links)
* @link_usb4: Upstream link is USB4
* @generation: Switch Thunderbolt generation
* @cap_plug_events: Offset to the plug events capability (%0 if not found)
@@ -178,6 +179,7 @@ struct tb_switch {
const char *device_name;
unsigned int link_speed;
enum tb_link_width link_width;
+ enum tb_link_width preferred_link_width;
bool link_usb4;
unsigned int generation;
int cap_plug_events;
--
2.43.0
