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thunderbolt: Keep link as asymmetric if preferred by hardware

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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@linux.intel.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
This commit is contained in:
Gil Fine 2023-12-04 15:14:58 +02:00 committed by Mika Westerberg
parent 2cd3da4e37
commit ba2a2a86de
3 changed files with 36 additions and 7 deletions
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13
drivers/thunderbolt/switch.c
View File

@ -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));
}
/**

28
drivers/thunderbolt/tb.c
View File

@ -1173,14 +1173,15 @@ 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;
@ -1229,6 +1230,19 @@ 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);
@ -1282,7 +1296,7 @@ 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 */
@ -1467,7 +1481,7 @@ 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);
@ -2289,7 +2303,7 @@ 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
@ -2332,7 +2346,7 @@ 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;
}
@ -2340,7 +2354,7 @@ 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;

2
drivers/thunderbolt/tb.h
View File

@ -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;