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SubjectRE: [RFC PATCH 19/22] thunderbolt: Add support for Time Management Unit
Date
Hi Mika,

> -----Original Message-----
> From: Mika Westerberg [mailto:mika.westerberg@linux.intel.com]
> Sent: Tuesday, October 01, 2019 4:38 AM
> To: linux-usb@vger.kernel.org
> Cc: Andreas Noever <andreas.noever@gmail.com>; Jamet, Michael
> <michael.jamet@intel.com>; Mika Westerberg
> <mika.westerberg@linux.intel.com>; Yehezkel Bernat
> <YehezkelShB@gmail.com>; Mani, Rajmohan <rajmohan.mani@intel.com>;
> Nicholas Johnson <nicholas.johnson-opensource@outlook.com.au>; Lukas
> Wunner <lukas@wunner.de>; Greg Kroah-Hartman
> <gregkh@linuxfoundation.org>; Alan Stern <stern@rowland.harvard.edu>;
> Mario.Limonciello@dell.com; Anthony Wong
> <anthony.wong@canonical.com>; linux-kernel@vger.kernel.org
> Subject: [RFC PATCH 19/22] thunderbolt: Add support for Time Management
> Unit
>
> From: Rajmohan Mani <rajmohan.mani@intel.com>
>
> Time Management Unit (TMU) is included in each USB4 router. It is used to
> synchronize time across the USB4 fabric. By default when USB4 router is
> plugged to the domain, its TMU is turned off. This differs from Thunderbolt (1,
> 2 and 3) devices whose TMU is by default configured to bi-directional HiFi
> mode. Since time synchronization is needed for proper Display Port tunneling
> this means we need to configure the TMU on
> USB4 compliant devices.
>
> The USB4 spec allows some flexibility on how the TMU can be configured.
> This makes it possible to enable link power management states (CLx) in certain
> topologies, where for example DP tunneling is not used. TMU can also be re-
> configured dynamicaly depending on types of tunnels created over the USB4
> fabric.
>
> In this patch we simply configure the TMU to be in bi-directional HiFi mode.
> This way we can tunnel any kind of traffic without need to perform complex
> steps to re-configure the domain dynamically. We can add more fine-grained
> TMU configuration later on when we start enabling CLx states.
>
> Signed-off-by: Rajmohan Mani <rajmohan.mani@intel.com>
> Co-developed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
> Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
> ---
> drivers/thunderbolt/Makefile | 2 +-
> drivers/thunderbolt/switch.c | 4 +
> drivers/thunderbolt/tb.c | 29 +++
> drivers/thunderbolt/tb.h | 47 +++++
> drivers/thunderbolt/tb_regs.h | 20 ++
> drivers/thunderbolt/tmu.c | 380 ++++++++++++++++++++++++++++++++++
> 6 files changed, 481 insertions(+), 1 deletion(-) create mode 100644
> drivers/thunderbolt/tmu.c
>
> diff --git a/drivers/thunderbolt/Makefile b/drivers/thunderbolt/Makefile index
> c0b2fd73dfbd..2014bc840b06 100644
> --- a/drivers/thunderbolt/Makefile
> +++ b/drivers/thunderbolt/Makefile
> @@ -1,4 +1,4 @@
> # SPDX-License-Identifier: GPL-2.0-only obj-${CONFIG_THUNDERBOLT} :=
> thunderbolt.o thunderbolt-objs := nhi.o nhi_ops.o ctl.o tb.o switch.o cap.o
> path.o tunnel.o eeprom.o -thunderbolt-objs += domain.o dma_port.o icm.o
> property.o xdomain.o lc.o usb4.o
> +thunderbolt-objs += domain.o dma_port.o icm.o property.o xdomain.o lc.o
> +tmu.o usb4.o
> diff --git a/drivers/thunderbolt/switch.c b/drivers/thunderbolt/switch.c index
> 2ccd1004920e..58e3f54ddbb9 100644
> --- a/drivers/thunderbolt/switch.c
> +++ b/drivers/thunderbolt/switch.c
> @@ -2278,6 +2278,10 @@ int tb_switch_add(struct tb_switch *sw)
> ret = tb_switch_update_link_attributes(sw);
> if (ret)
> return ret;
> +
> + ret = tb_switch_tmu_init(sw);
> + if (ret)
> + return ret;
> }
>
> ret = device_add(&sw->dev);
> diff --git a/drivers/thunderbolt/tb.c b/drivers/thunderbolt/tb.c index
> 24e37e47dc48..f2868c125637 100644
> --- a/drivers/thunderbolt/tb.c
> +++ b/drivers/thunderbolt/tb.c
> @@ -161,6 +161,25 @@ static void tb_scan_xdomain(struct tb_port *port)
> }
> }
>
> +static int tb_enable_tmu(struct tb_switch *sw) {
> + int ret;
> +
> + /* If it is already enabled in correct mode, don't touch it */
> + if (tb_switch_tmu_is_enabled(sw))
> + return 0;
> +
> + ret = tb_switch_tmu_disable(sw);
> + if (ret)
> + return ret;
> +
> + ret = tb_switch_tmu_post_time(sw);
> + if (ret)
> + return ret;
> +
> + return tb_switch_tmu_enable(sw);
> +}
> +
> static void tb_scan_port(struct tb_port *port);
>
> /**
> @@ -263,6 +282,9 @@ static void tb_scan_port(struct tb_port *port)
> if (tb_switch_lane_bonding_enable(sw))
> tb_sw_warn(sw, "failed to enable lane bonding\n");
>
> + if (tb_enable_tmu(sw))
> + tb_sw_warn(sw, "failed to enable TMU\n");
> +
> tb_scan_switch(sw);
> }
>
> @@ -713,6 +735,7 @@ static void tb_handle_hotplug(struct work_struct
> *work)
> tb_sw_set_unplugged(port->remote->sw);
> tb_free_invalid_tunnels(tb);
> tb_remove_dp_resources(port->remote->sw);
> + tb_switch_tmu_disable(port->remote->sw);
> tb_switch_lane_bonding_disable(port->remote->sw);
> tb_switch_remove(port->remote->sw);
> port->remote = NULL;
> @@ -860,6 +883,9 @@ static int tb_start(struct tb *tb)
> return ret;
> }
>
> + /* Enable TMU if it is off */
> + if (!tb_switch_tmu_is_enabled(tb->root_switch))

To be consistent with the implementation of tb_switch_tmu_disable(), should we
move the above check inside tb_switch_tmu_enable()?

> + tb_switch_tmu_enable(tb->root_switch);
> /* Full scan to discover devices added before the driver was loaded. */
> tb_scan_switch(tb->root_switch);
> /* Find out tunnels created by the boot firmware */ @@ -891,6 +917,9
> @@ static void tb_restore_children(struct tb_switch *sw) {
> int i;
>
> + if (tb_enable_tmu(sw))
> + tb_sw_warn(sw, "failed to restore TMU configuration\n");
> +
> tb_switch_for_each_remote_port(sw, i) {
> struct tb_port *port = &sw->ports[i];
>
> diff --git a/drivers/thunderbolt/tb.h b/drivers/thunderbolt/tb.h index
> 1488382066fd..087fd6d6ef9a 100644
> --- a/drivers/thunderbolt/tb.h
> +++ b/drivers/thunderbolt/tb.h
> @@ -46,6 +46,38 @@ struct tb_switch_nvm {
> #define TB_SWITCH_MAX_DEPTH 6
> #define USB4_SWITCH_MAX_DEPTH 5
>
> +/**
> + * enum tb_switch_tmu_rate - TMU refresh rate
> + * @TB_SWITCH_TMU_RATE_OFF: %0 (Disable Time Sync handshake)
> + * @TB_SWITCH_TMU_RATE_HIFI: %16 us time interval between successive
> + * transmission of the Delay Request TSNOS
> + * (Time Sync Notification Ordered Set) on a Link
> + * @TB_SWITCH_TMU_RATE_NORMAL: %1 ms time interval between
> successive
> + * transmission of the Delay Request TSNOS on
> + * a Link
> + */
> +enum tb_switch_tmu_rate {
> + TB_SWITCH_TMU_RATE_OFF = 0,
> + TB_SWITCH_TMU_RATE_HIFI = 16,
> + TB_SWITCH_TMU_RATE_NORMAL = 1000,
> +};
> +
> +/**
> + * struct tb_switch_tmu - Structure holding switch TMU configuration
> + * @cap: Offset to the TMU capability (%0 if not found)
> + * @has_ucap: Does the switch support uni-directional mode
> + * @rate: TMU refresh rate related to upstream switch. In case of root
> + * switch this holds the domain rate.
> + * @unidirectional: Is the TMU in uni-directional or bi-directional mode
> + * related to upstream switch. Don't case for root switch.
> + */
> +struct tb_switch_tmu {
> + int cap;
> + bool has_ucap;
> + enum tb_switch_tmu_rate rate;
> + bool unidirectional;
> +};
> +
> /**
> * struct tb_switch - a thunderbolt switch
> * @dev: Device for the switch
> @@ -55,6 +87,7 @@ struct tb_switch_nvm {
> * mailbox this will hold the pointer to that (%NULL
> * otherwise). If set it also means the switch has
> * upgradeable NVM.
> + * @tmu: The switch TMU configuration
> * @tb: Pointer to the domain the switch belongs to
> * @uid: Unique ID of the switch
> * @uuid: UUID of the switch (or %NULL if not supported) @@ -93,6 +126,7
> @@ struct tb_switch {
> struct tb_regs_switch_header config;
> struct tb_port *ports;
> struct tb_dma_port *dma_port;
> + struct tb_switch_tmu tmu;
> struct tb *tb;
> u64 uid;
> uuid_t *uuid;
> @@ -129,6 +163,7 @@ struct tb_switch {
> * @remote: Remote port (%NULL if not connected)
> * @xdomain: Remote host (%NULL if not connected)
> * @cap_phy: Offset, zero if not found
> + * @cap_tmu: Offset of the adapter specific TMU capability (%0 if not
> + present)
> * @cap_adap: Offset of the adapter specific capability (%0 if not present)
> * @cap_usb4: Offset to the USB4 port capability (%0 if not present)
> * @port: Port number on switch
> @@ -147,6 +182,7 @@ struct tb_port {
> struct tb_port *remote;
> struct tb_xdomain *xdomain;
> int cap_phy;
> + int cap_tmu;
> int cap_adap;
> int cap_usb4;
> u8 port;
> @@ -696,6 +732,17 @@ bool tb_switch_query_dp_resource(struct tb_switch
> *sw, struct tb_port *in); int tb_switch_alloc_dp_resource(struct tb_switch
> *sw, struct tb_port *in); void tb_switch_dealloc_dp_resource(struct tb_switch
> *sw, struct tb_port *in);
>
> +int tb_switch_tmu_init(struct tb_switch *sw); int
> +tb_switch_tmu_post_time(struct tb_switch *sw); int
> +tb_switch_tmu_disable(struct tb_switch *sw); int
> +tb_switch_tmu_enable(struct tb_switch *sw);
> +
> +static inline bool tb_switch_tmu_is_enabled(const struct tb_switch *sw)
> +{
> + return sw->tmu.rate == TB_SWITCH_TMU_RATE_HIFI &&
> + !sw->tmu.unidirectional;
> +}
> +
> int tb_wait_for_port(struct tb_port *port, bool wait_if_unplugged); int
> tb_port_add_nfc_credits(struct tb_port *port, int credits); int
> tb_port_set_initial_credits(struct tb_port *port, u32 credits); diff --git
> a/drivers/thunderbolt/tb_regs.h b/drivers/thunderbolt/tb_regs.h index
> 47f73f992412..ec1a5d1f7c94 100644
> --- a/drivers/thunderbolt/tb_regs.h
> +++ b/drivers/thunderbolt/tb_regs.h
> @@ -26,6 +26,7 @@
> #define TB_MAX_CONFIG_RW_LENGTH 60
>
> enum tb_switch_cap {
> + TB_SWITCH_CAP_TMU = 0x03,
> TB_SWITCH_CAP_VSE = 0x05,
> };
>
> @@ -195,6 +196,21 @@ struct tb_regs_switch_header {
> #define ROUTER_CS_26_ONS BIT(30)
> #define ROUTER_CS_26_OV BIT(31)
>
> +/* Router TMU configuration */
> +#define TMU_RTR_CS_0 0x00
> +#define TMU_RTR_CS_0_TD BIT(27)
> +#define TMU_RTR_CS_0_UCAP BIT(30)
> +#define TMU_RTR_CS_1 0x01
> +#define TMU_RTR_CS_1_LOCAL_TIME_NS_MASK GENMASK(31,
> 16)
> +#define TMU_RTR_CS_1_LOCAL_TIME_NS_SHIFT 16
> +#define TMU_RTR_CS_2 0x02
> +#define TMU_RTR_CS_3 0x03
> +#define TMU_RTR_CS_3_LOCAL_TIME_NS_MASK GENMASK(15,
> 0)
> +#define TMU_RTR_CS_3_TS_PACKET_INTERVAL_MASK GENMASK(31,
> 16)
> +#define TMU_RTR_CS_3_TS_PACKET_INTERVAL_SHIFT 16
> +#define TMU_RTR_CS_22 0x16
> +#define TMU_RTR_CS_24 0x18
> +
> enum tb_port_type {
> TB_TYPE_INACTIVE = 0x000000,
> TB_TYPE_PORT = 0x000001,
> @@ -248,6 +264,10 @@ struct tb_regs_port_header {
> #define ADP_CS_5_LCA_MASK GENMASK(28, 22)
> #define ADP_CS_5_LCA_SHIFT 22
>
> +/* TMU adapter registers */
> +#define TMU_ADP_CS_3 0x03
> +#define TMU_ADP_CS_3_UDM BIT(29)
> +
> /* Lane adapter registers */
> #define LANE_ADP_CS_0 0x00
> #define LANE_ADP_CS_0_SUPPORTED_WIDTH_MASK GENMASK(25, 20)
> diff --git a/drivers/thunderbolt/tmu.c b/drivers/thunderbolt/tmu.c new file
> mode 100644 index 000000000000..d6314f6b20c7
> --- /dev/null
> +++ b/drivers/thunderbolt/tmu.c
> @@ -0,0 +1,380 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Thunderbolt Time Management Unit (TMU) support
> + *
> + * Copyright (C) 2019, Intel Corporation
> + * Authors: Mika Westerberg <mika.westerberg@linux.intel.com>
> + * Rajmohan Mani <rajmohan.mani@intel.com>
> + */
> +
> +#include <linux/delay.h>
> +
> +#include "tb.h"
> +
> +static const char *tb_switch_tmu_mode_name(const struct tb_switch *sw)
> +{
> + bool root_switch = !tb_route(sw);
> +
> + switch (sw->tmu.rate) {
> + case TB_SWITCH_TMU_RATE_OFF:
> + return "off";
> +
> + case TB_SWITCH_TMU_RATE_HIFI:
> + /* Root switch does not have upstream directionality */
> + if (root_switch)
> + return "HiFi";
> + if (sw->tmu.unidirectional)
> + return "uni-directional, HiFi";
> + return "bi-directional, HiFi";
> +
> + case TB_SWITCH_TMU_RATE_NORMAL:
> + if (root_switch)
> + return "normal";
> + return "uni-directional, normal";
> +
> + default:
> + return "unknown";
> + }
> +}
> +
> +static bool tb_switch_tmu_ucap_supported(struct tb_switch *sw) {
> + int ret;
> + u32 val;
> +
> + ret = tb_sw_read(sw, &val, TB_CFG_SWITCH,
> + sw->tmu.cap + TMU_RTR_CS_0, 1);
> + if (ret)
> + return false;
> +
> + return !!(val & TMU_RTR_CS_0_UCAP);
> +}
> +
> +static int tb_switch_tmu_rate_read(struct tb_switch *sw) {
> + int ret;
> + u32 val;
> +
> + ret = tb_sw_read(sw, &val, TB_CFG_SWITCH,
> + sw->tmu.cap + TMU_RTR_CS_3, 1);
> + if (ret)
> + return ret;
> +
> + val >>= TMU_RTR_CS_3_TS_PACKET_INTERVAL_SHIFT;
> + return val;
> +}
> +
> +static int tb_switch_tmu_rate_write(struct tb_switch *sw, int rate) {
> + int ret;
> + u32 val;
> +
> + ret = tb_sw_read(sw, &val, TB_CFG_SWITCH,
> + sw->tmu.cap + TMU_RTR_CS_3, 1);
> + if (ret)
> + return ret;
> +
> + val &= ~TMU_RTR_CS_3_TS_PACKET_INTERVAL_MASK;
> + val |= rate << TMU_RTR_CS_3_TS_PACKET_INTERVAL_SHIFT;
> +
> + return tb_sw_write(sw, &val, TB_CFG_SWITCH,
> + sw->tmu.cap + TMU_RTR_CS_3, 1);
> +}
> +
> +static int tb_port_tmu_write(struct tb_port *port, u8 offset, u32 mask,
> + u32 value)
> +{
> + u32 data;
> + int ret;
> +
> + ret = tb_port_read(port, &data, TB_CFG_PORT, port->cap_tmu +
> offset, 1);
> + if (ret)
> + return ret;
> +
> + data &= ~mask;
> + data |= value;
> +
> + return tb_port_write(port, &data, TB_CFG_PORT,
> + port->cap_tmu + offset, 1);
> +}
> +
> +static int tb_port_tmu_set_unidirectional(struct tb_port *port,
> + bool unidirectional)
> +{
> + u32 val;
> +
> + if (!port->sw->tmu.has_ucap)
> + return 0;
> +
> + val = unidirectional ? TMU_ADP_CS_3_UDM : 0;
> + return tb_port_tmu_write(port, TMU_ADP_CS_3,
> TMU_ADP_CS_3_UDM, val); }
> +
> +static inline int tb_port_tmu_unidirectional_disable(struct tb_port
> +*port) {
> + return tb_port_tmu_set_unidirectional(port, false); }
> +
> +static bool tb_port_tmu_is_unidirectional(struct tb_port *port) {
> + int ret;
> + u32 val;
> +
> + ret = tb_port_read(port, &val, TB_CFG_PORT,
> + port->cap_tmu + TMU_ADP_CS_3, 1);
> + if (ret)
> + return false;
> +
> + return val & TMU_ADP_CS_3_UDM;
> +}
> +
> +static int tb_switch_tmu_set_time_disruption(struct tb_switch *sw, bool
> +set) {
> + int ret;
> + u32 val;
> +
> + ret = tb_sw_read(sw, &val, TB_CFG_SWITCH,
> + sw->tmu.cap + TMU_RTR_CS_0, 1);
> + if (ret)
> + return ret;
> +
> + if (set)
> + val |= TMU_RTR_CS_0_TD;
> + else
> + val &= ~TMU_RTR_CS_0_TD;
> +
> + return tb_sw_write(sw, &val, TB_CFG_SWITCH,
> + sw->tmu.cap + TMU_RTR_CS_0, 1);
> +}
> +
> +/**
> + * tb_switch_tmu_init() - Initialize switch TMU structures
> + * @sw: Switch to initialized
> + *
> + * This function must be called before other TMU related functions to
> + * makes the internal structures are filled in correctly. Does not
> + * change any hardware configuration.
> + */
> +int tb_switch_tmu_init(struct tb_switch *sw) {
> + int ret, i;
> +
> + if (tb_switch_is_icm(sw))
> + return 0;
> +
> + ret = tb_switch_find_cap(sw, TB_SWITCH_CAP_TMU);
> + if (ret > 0)
> + sw->tmu.cap = ret;
> +
> + tb_switch_for_each_port(sw, i) {
> + struct tb_port *port = &sw->ports[i];
> + int cap;
> +
> + cap = tb_port_find_cap(port, TB_PORT_CAP_TIME1);
> + if (cap > 0)
> + port->cap_tmu = cap;
> + }
> +
> + ret = tb_switch_tmu_rate_read(sw);
> + if (ret < 0)
> + return ret;
> +
> + sw->tmu.rate = ret;
> +
> + sw->tmu.has_ucap = tb_switch_tmu_ucap_supported(sw);
> + if (sw->tmu.has_ucap) {
> + tb_sw_dbg(sw, "TMU: supports uni-directional mode\n");
> +
> + if (tb_route(sw)) {
> + struct tb_port *up = tb_upstream_port(sw);
> +
> + sw->tmu.unidirectional =
> + tb_port_tmu_is_unidirectional(up);
> + }
> + } else {
> + sw->tmu.unidirectional = false;
> + }
> +
> + tb_sw_dbg(sw, "TMU: current mode: %s\n",
> tb_switch_tmu_mode_name(sw));
> + return 0;
> +}
> +
> +/**
> + * tb_switch_tmu_post_time() - Update switch local time
> + * @sw: Switch whose time to update
> + *
> + * Updates switch local time using time posting procedure.
> + */
> +int tb_switch_tmu_post_time(struct tb_switch *sw) {
> + unsigned int post_local_time_offset, post_time_offset;
> + struct tb_switch *root_switch = sw->tb->root_switch;
> + u64 hi, mid, lo, local_time, post_time;
> + int i, ret, retries = 100;
> + u32 gm_local_time[3];
> +
> + if (!tb_route(sw))
> + return 0;
> +
> + if (!tb_switch_is_usb4(sw))
> + return 0;
> +
> + /* Need to be able to read the grand master time */
> + if (!root_switch->tmu.cap)
> + return 0;
> +
> + ret = tb_sw_read(root_switch, gm_local_time, TB_CFG_SWITCH,
> + root_switch->tmu.cap + TMU_RTR_CS_1,
> + ARRAY_SIZE(gm_local_time));
> + if (ret)
> + return ret;
> +
> + for (i = 0; i < ARRAY_SIZE(gm_local_time); i++)
> + tb_sw_dbg(root_switch, "local_time[%d]=0x%08x\n", i,
> + gm_local_time[i]);
> +
> + /* Convert to nanoseconds (drop fractional part) */
> + hi = gm_local_time[2] & TMU_RTR_CS_3_LOCAL_TIME_NS_MASK;
> + mid = gm_local_time[1];
> + lo = (gm_local_time[0] & TMU_RTR_CS_1_LOCAL_TIME_NS_MASK) >>
> + TMU_RTR_CS_1_LOCAL_TIME_NS_SHIFT;
> + local_time = hi << 48 | mid << 16 | lo;
> +
> + /* Tell the switch that time sync is disrupted for a while */
> + ret = tb_switch_tmu_set_time_disruption(sw, true);
> + if (ret)
> + return ret;
> +
> + post_local_time_offset = sw->tmu.cap + TMU_RTR_CS_22;
> + post_time_offset = sw->tmu.cap + TMU_RTR_CS_24;
> +
> + /*
> + * Write the Grandmaster time to the Post Local Time registers
> + * of the new switch.
> + */
> + ret = tb_sw_write(sw, &local_time, TB_CFG_SWITCH,
> + post_local_time_offset, 2);
> + if (ret)
> + goto out;
> +
> + /*
> + * Have the new switch update its local time (by writing 1 to
> + * the post_time registers) and wait for the completion of the
> + * same (post_time register becomes 0). This means the time has
> + * been converged properly.
> + */
> + post_time = 1;
> +
> + ret = tb_sw_write(sw, &post_time, TB_CFG_SWITCH, post_time_offset,
> 2);
> + if (ret)
> + goto out;
> +
> + do {
> + usleep_range(5, 10);
> + ret = tb_sw_read(sw, &post_time, TB_CFG_SWITCH,
> + post_time_offset, 2);
> + if (ret)
> + goto out;
> + } while (--retries && post_time);
> +
> + if (!retries) {
> + ret = -ETIMEDOUT;
> + goto out;
> + }
> +
> + tb_sw_dbg(sw, "TMU: updated local time to %#llx\n", local_time);
> +
> +out:
> + tb_switch_tmu_set_time_disruption(sw, false);
> + return ret;
> +}
> +
> +/**
> + * tb_switch_tmu_disable() - Disable TMU of a switch
> + * @sw: Switch whose TMU to disable
> + *
> + * Turns off TMU of @sw if it is enabled. If not enabled does nothing.
> + */
> +int tb_switch_tmu_disable(struct tb_switch *sw) {
> + int ret;
> +
> + if (!tb_switch_is_usb4(sw))
> + return 0;
> +
> + /* Already disabled? */
> + if (sw->tmu.rate == TB_SWITCH_TMU_RATE_OFF)
> + return 0;
> +
> + if (sw->tmu.unidirectional) {
> + struct tb_switch *parent = tb_switch_parent(sw);
> + struct tb_port *up, *down;
> +
> + up = tb_upstream_port(sw);
> + down = tb_port_at(tb_route(sw), parent);
> +
> + /* The switch may be unplugged so ignore any errors */
> + tb_port_tmu_unidirectional_disable(up);
> + ret = tb_port_tmu_unidirectional_disable(down);
> + if (ret)
> + return ret;
> + }
> +
> + tb_switch_tmu_rate_write(sw, TB_SWITCH_TMU_RATE_OFF);
> +
> + sw->tmu.unidirectional = false;
> + sw->tmu.rate = TB_SWITCH_TMU_RATE_OFF;
> +
> + tb_sw_dbg(sw, "TMU: disabled\n");
> + return 0;
> +}
> +
> +/**
> + * tb_switch_tmu_enable() - Enable TMU on a switch
> + * @sw: Switch whose TMU to enable
> + *
> + * Enables TMU of a switch to be in bi-directional, HiFi mode. In this
> +mode
> + * all tunneling should work.
> + */
> +int tb_switch_tmu_enable(struct tb_switch *sw) {
> + int ret;
> +
> + if (!tb_switch_is_usb4(sw))
> + return 0;
> +
> + ret = tb_switch_tmu_set_time_disruption(sw, true);
> + if (ret)
> + return ret;
> +
> + /* Change mode to bi-directional */
> + if (tb_route(sw) && sw->tmu.unidirectional) {
> + struct tb_switch *parent = tb_switch_parent(sw);
> + struct tb_port *up, *down;
> +
> + up = tb_upstream_port(sw);
> + down = tb_port_at(tb_route(sw), parent);
> +
> + ret = tb_port_tmu_unidirectional_disable(down);
> + if (ret)
> + return ret;
> +
> + ret = tb_switch_tmu_rate_write(sw,
> TB_SWITCH_TMU_RATE_HIFI);
> + if (ret)
> + return ret;
> +
> + ret = tb_port_tmu_unidirectional_disable(up);
> + if (ret)
> + return ret;
> + } else {
> + ret = tb_switch_tmu_rate_write(sw,
> TB_SWITCH_TMU_RATE_HIFI);
> + if (ret)
> + return ret;
> + }
> +
> + sw->tmu.unidirectional = false;
> + sw->tmu.rate = TB_SWITCH_TMU_RATE_HIFI;
> + tb_sw_dbg(sw, "TMU: mode set to: %s\n",
> tb_switch_tmu_mode_name(sw));
> +
> + return tb_switch_tmu_set_time_disruption(sw, false); }
> --
> 2.23.0

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