[PATCH 0/2] Add support for downstream port reset(DPR)

[PATCH 0/2] Add support for downstream port reset(DPR)

[Sanath S]

Tunnels created by boot firmware results in incorrect PCI resource
allocation, which results in failure of extending daisy chain.

This series aligns with windows behaviour of performing a teardown of
tunnels and resetting the downstream ports using DPR during the init
sequence.

Sanath S (2):
  thunderbolt: Introduce tb_switch_reset_ports(), tb_port_reset() and
    usb4_port_reset()
  thunderbolt: Teardown tunnels and reset downstream ports created by
    boot firmware

 drivers/thunderbolt/switch.c  |  31 ++++++++
 drivers/thunderbolt/tb.c      | 137 ++--------------------------------
 drivers/thunderbolt/tb.h      |   2 +
 drivers/thunderbolt/tb_regs.h |   1 +
 drivers/thunderbolt/usb4.c    |  39 ++++++++++
 5 files changed, 80 insertions(+), 130 deletions(-)

-- 
2.34.1

[PATCH 1/2] thunderbolt: Introduce tb_switch_reset_ports(), tb_port_reset() and usb4_port_reset()

[Sanath S]

Introduce the tb_switch_reset_ports() function that resets the
downstream ports of a given switch. This helps us reset the USB4
links created by boot firmware during the init sequence.

Introduce the tb_port_reset() helper function that resets the
given port.

Introduce the usb4_port_reset() function that performs the DPR
of a given port. This function follows the CM guide specification 7.3

Suggested-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Sanath S <Sanath.S@amd.com>
---
 drivers/thunderbolt/switch.c  | 31 ++++++++++++++++++++++++++++
 drivers/thunderbolt/tb.h      |  2 ++
 drivers/thunderbolt/tb_regs.h |  1 +
 drivers/thunderbolt/usb4.c    | 39 +++++++++++++++++++++++++++++++++++
 4 files changed, 73 insertions(+)

diff --git a/drivers/thunderbolt/switch.c b/drivers/thunderbolt/switch.c
index 44e9b09de47a..26ad6cc1ee91 100644
--- a/drivers/thunderbolt/switch.c
+++ b/drivers/thunderbolt/switch.c
@@ -626,6 +626,19 @@ int tb_port_unlock(struct tb_port *port)
 	return 0;
 }
 
+/**
+ * tb_port_reset() - Reset downstream port
+ * @port: Port to reset
+ *
+ * Helps to reconfigure the USB4 link by resetting the downstream port.
+ *
+ * Return: Returns 0 on success or an error code on failure.
+ */
+static int tb_port_reset(struct tb_port *port)
+{
+	return usb4_port_reset(port);
+}
+
 static int __tb_port_enable(struct tb_port *port, bool enable)
 {
 	int ret;
@@ -1547,6 +1560,24 @@ static void tb_dump_switch(const struct tb *tb, const struct tb_switch *sw)
 	       regs->__unknown1, regs->__unknown4);
 }
 
+/**
+ * tb_switch_reset_ports() - Reset downstream ports of switch.
+ * @sw: Switch whose ports need to be reset.
+ *
+ * Return: Returns 0 on success or an error code on failure.
+ */
+int tb_switch_reset_ports(struct tb_switch *sw)
+{
+	struct tb_port *port;
+	int ret = -EINVAL;
+
+	tb_switch_for_each_port(sw, port) {
+		if (tb_port_is_null(port) && port->cap_usb4)
+			ret = tb_port_reset(port);
+	}
+	return ret;
+}
+
 /**
  * tb_switch_reset() - reconfigure route, enable and send TB_CFG_PKG_RESET
  * @sw: Switch to reset
diff --git a/drivers/thunderbolt/tb.h b/drivers/thunderbolt/tb.h
index e299e53473ae..f2687ec4ac53 100644
--- a/drivers/thunderbolt/tb.h
+++ b/drivers/thunderbolt/tb.h
@@ -797,6 +797,7 @@ void tb_switch_remove(struct tb_switch *sw);
 void tb_switch_suspend(struct tb_switch *sw, bool runtime);
 int tb_switch_resume(struct tb_switch *sw);
 int tb_switch_reset(struct tb_switch *sw);
+int tb_switch_reset_ports(struct tb_switch *sw);
 int tb_switch_wait_for_bit(struct tb_switch *sw, u32 offset, u32 bit,
 			   u32 value, int timeout_msec);
 void tb_sw_set_unplugged(struct tb_switch *sw);
@@ -1281,6 +1282,7 @@ struct tb_port *usb4_switch_map_usb3_down(struct tb_switch *sw,
 int usb4_switch_add_ports(struct tb_switch *sw);
 void usb4_switch_remove_ports(struct tb_switch *sw);
 
+int usb4_port_reset(struct tb_port *port);
 int usb4_port_unlock(struct tb_port *port);
 int usb4_port_hotplug_enable(struct tb_port *port);
 int usb4_port_configure(struct tb_port *port);
diff --git a/drivers/thunderbolt/tb_regs.h b/drivers/thunderbolt/tb_regs.h
index 87e4795275fe..d49530bc0d53 100644
--- a/drivers/thunderbolt/tb_regs.h
+++ b/drivers/thunderbolt/tb_regs.h
@@ -389,6 +389,7 @@ struct tb_regs_port_header {
 #define PORT_CS_18_CSA				BIT(22)
 #define PORT_CS_18_TIP				BIT(24)
 #define PORT_CS_19				0x13
+#define PORT_CS_19_DPR				BIT(0)
 #define PORT_CS_19_PC				BIT(3)
 #define PORT_CS_19_PID				BIT(4)
 #define PORT_CS_19_WOC				BIT(16)
diff --git a/drivers/thunderbolt/usb4.c b/drivers/thunderbolt/usb4.c
index 4277733d0021..55f7c163bf84 100644
--- a/drivers/thunderbolt/usb4.c
+++ b/drivers/thunderbolt/usb4.c
@@ -1073,6 +1073,45 @@ void usb4_switch_remove_ports(struct tb_switch *sw)
 	}
 }
 
+/**
+ * usb4_port_reset() - Reset USB4 downsteam port
+ * @port: USB4 port to reset.
+ *
+ * Helps to reconfigure USB4 link by resetting downstream port.
+ *
+ * Return: Returns 0 on success or an error code on failure.
+ */
+int usb4_port_reset(struct tb_port *port)
+{
+	int ret;
+	u32 val = 0;
+
+	ret = tb_port_read(port, &val, TB_CFG_PORT,
+			port->cap_usb4 + PORT_CS_19, 1);
+	if (ret)
+		return ret;
+
+	val = val | PORT_CS_19_DPR;
+	ret = tb_port_write(port, &val, TB_CFG_PORT,
+			port->cap_usb4 + PORT_CS_19, 1);
+	if (ret)
+		return ret;
+
+	/* Wait for 10ms after requesting downstream port reset */
+	msleep(10);
+
+	ret = tb_port_read(port, &val, TB_CFG_PORT,
+			port->cap_usb4 + PORT_CS_19, 1);
+	if (ret)
+		return ret;
+
+	val &= ~PORT_CS_19_DPR;
+	ret = tb_port_write(port, &val, TB_CFG_PORT,
+			port->cap_usb4 + PORT_CS_19, 1);
+
+	return ret;
+}
+
 /**
  * usb4_port_unlock() - Unlock USB4 downstream port
  * @port: USB4 port to unlock
-- 
2.34.1

[PATCH 2/2] thunderbolt: Teardown tunnels and reset downstream ports created by boot firmware

[Sanath S]

Boot firmware might have created tunnels of its own. Since we cannot
be sure they are usable for us. Tear them down and reset the ports
to handle it as a new hotplug.

Since we teardown the tunnels, Discovering of tunnels is not needed.
Removing helper functions tb_discover_tunnels(),
tb_discover_dp_resources(), tb_create_usb3_tunnels(),
tb_add_dp_resources() and device_for_each_child().

Suggested-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Sanath S <Sanath.S@amd.com>
---
 drivers/thunderbolt/tb.c | 137 ++-------------------------------------
 1 file changed, 7 insertions(+), 130 deletions(-)

diff --git a/drivers/thunderbolt/tb.c b/drivers/thunderbolt/tb.c
index fd49f86e0353..bfad14846514 100644
--- a/drivers/thunderbolt/tb.c
+++ b/drivers/thunderbolt/tb.c
@@ -151,24 +151,6 @@ tb_attach_bandwidth_group(struct tb_cm *tcm, struct tb_port *in,
 	return group;
 }
 
-static void tb_discover_bandwidth_group(struct tb_cm *tcm, struct tb_port *in,
-					struct tb_port *out)
-{
-	if (usb4_dp_port_bandwidth_mode_enabled(in)) {
-		int index, i;
-
-		index = usb4_dp_port_group_id(in);
-		for (i = 0; i < ARRAY_SIZE(tcm->groups); i++) {
-			if (tcm->groups[i].index == index) {
-				tb_bandwidth_group_attach_port(&tcm->groups[i], in);
-				return;
-			}
-		}
-	}
-
-	tb_attach_bandwidth_group(tcm, in, out);
-}
-
 static void tb_detach_bandwidth_group(struct tb_port *in)
 {
 	struct tb_bandwidth_group *group = in->group;
@@ -247,32 +229,6 @@ static void tb_remove_dp_resources(struct tb_switch *sw)
 	}
 }
 
-static void tb_discover_dp_resource(struct tb *tb, struct tb_port *port)
-{
-	struct tb_cm *tcm = tb_priv(tb);
-	struct tb_port *p;
-
-	list_for_each_entry(p, &tcm->dp_resources, list) {
-		if (p == port)
-			return;
-	}
-
-	tb_port_dbg(port, "DP %s resource available discovered\n",
-		    tb_port_is_dpin(port) ? "IN" : "OUT");
-	list_add_tail(&port->list, &tcm->dp_resources);
-}
-
-static void tb_discover_dp_resources(struct tb *tb)
-{
-	struct tb_cm *tcm = tb_priv(tb);
-	struct tb_tunnel *tunnel;
-
-	list_for_each_entry(tunnel, &tcm->tunnel_list, list) {
-		if (tb_tunnel_is_dp(tunnel))
-			tb_discover_dp_resource(tb, tunnel->dst_port);
-	}
-}
-
 /* Enables CL states up to host router */
 static int tb_enable_clx(struct tb_switch *sw)
 {
@@ -472,34 +428,6 @@ static void tb_switch_discover_tunnels(struct tb_switch *sw,
 	}
 }
 
-static void tb_discover_tunnels(struct tb *tb)
-{
-	struct tb_cm *tcm = tb_priv(tb);
-	struct tb_tunnel *tunnel;
-
-	tb_switch_discover_tunnels(tb->root_switch, &tcm->tunnel_list, true);
-
-	list_for_each_entry(tunnel, &tcm->tunnel_list, list) {
-		if (tb_tunnel_is_pci(tunnel)) {
-			struct tb_switch *parent = tunnel->dst_port->sw;
-
-			while (parent != tunnel->src_port->sw) {
-				parent->boot = true;
-				parent = tb_switch_parent(parent);
-			}
-		} else if (tb_tunnel_is_dp(tunnel)) {
-			struct tb_port *in = tunnel->src_port;
-			struct tb_port *out = tunnel->dst_port;
-
-			/* Keep the domain from powering down */
-			pm_runtime_get_sync(&in->sw->dev);
-			pm_runtime_get_sync(&out->sw->dev);
-
-			tb_discover_bandwidth_group(tcm, in, out);
-		}
-	}
-}
-
 static int tb_port_configure_xdomain(struct tb_port *port, struct tb_xdomain *xd)
 {
 	if (tb_switch_is_usb4(port->sw))
@@ -1043,31 +971,6 @@ static int tb_tunnel_usb3(struct tb *tb, struct tb_switch *sw)
 	return ret;
 }
 
-static int tb_create_usb3_tunnels(struct tb_switch *sw)
-{
-	struct tb_port *port;
-	int ret;
-
-	if (!tb_acpi_may_tunnel_usb3())
-		return 0;
-
-	if (tb_route(sw)) {
-		ret = tb_tunnel_usb3(sw->tb, sw);
-		if (ret)
-			return ret;
-	}
-
-	tb_switch_for_each_port(sw, port) {
-		if (!tb_port_has_remote(port))
-			continue;
-		ret = tb_create_usb3_tunnels(port->remote->sw);
-		if (ret)
-			return ret;
-	}
-
-	return 0;
-}
-
 /**
  * tb_configure_asym() - Transition links to asymmetric if needed
  * @tb: Domain structure
@@ -2534,27 +2437,6 @@ static void tb_stop(struct tb *tb)
 	tcm->hotplug_active = false; /* signal tb_handle_hotplug to quit */
 }
 
-static int tb_scan_finalize_switch(struct device *dev, void *data)
-{
-	if (tb_is_switch(dev)) {
-		struct tb_switch *sw = tb_to_switch(dev);
-
-		/*
-		 * If we found that the switch was already setup by the
-		 * boot firmware, mark it as authorized now before we
-		 * send uevent to userspace.
-		 */
-		if (sw->boot)
-			sw->authorized = 1;
-
-		dev_set_uevent_suppress(dev, false);
-		kobject_uevent(&dev->kobj, KOBJ_ADD);
-		device_for_each_child(dev, NULL, tb_scan_finalize_switch);
-	}
-
-	return 0;
-}
-
 static int tb_start(struct tb *tb)
 {
 	struct tb_cm *tcm = tb_priv(tb);
@@ -2598,20 +2480,15 @@ static int tb_start(struct tb *tb)
 	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 */
-	tb_discover_tunnels(tb);
-	/* Add DP resources from the DP tunnels created by the boot firmware */
-	tb_discover_dp_resources(tb);
 	/*
-	 * If the boot firmware did not create USB 3.x tunnels create them
-	 * now for the whole topology.
+	 * Boot firmware might have created tunnels of its own. Since we cannot
+	 * be sure they are usable for us, Tear them down and reset the ports
+	 * to handle it as new hotplug.
 	 */
-	tb_create_usb3_tunnels(tb->root_switch);
-	/* Add DP IN resources for the root switch */
-	tb_add_dp_resources(tb->root_switch);
-	/* Make the discovered switches available to the userspace */
-	device_for_each_child(&tb->root_switch->dev, NULL,
-			      tb_scan_finalize_switch);
+	tb_switch_discover_tunnels(tb->root_switch, &tcm->tunnel_list, false);
+	ret = tb_switch_reset_ports(tb->root_switch);
+	if (ret)
+		return ret;
 
 	/* Allow tb_handle_hotplug to progress events */
 	tcm->hotplug_active = true;
-- 
2.34.1

Re: [PATCH 2/2] thunderbolt: Teardown tunnels and reset downstream ports created by boot firmware

[Mika Westerberg]

On Tue, Dec 12, 2023 at 07:30:47PM +0530, Sanath S wrote:
> Boot firmware might have created tunnels of its own. Since we cannot
> be sure they are usable for us. Tear them down and reset the ports
> to handle it as a new hotplug.
> 
> Since we teardown the tunnels, Discovering of tunnels is not needed.

Let's leave this for non-USB4 (That's TBT1-3) as we agreed.

Re: [PATCH 1/2] thunderbolt: Introduce tb_switch_reset_ports(), tb_port_reset() and usb4_port_reset()

[Mika Westerberg]

On Tue, Dec 12, 2023 at 07:30:46PM +0530, Sanath S wrote:
> Introduce the tb_switch_reset_ports() function that resets the
> downstream ports of a given switch. This helps us reset the USB4
> links created by boot firmware during the init sequence.
> 
> Introduce the tb_port_reset() helper function that resets the
> given port.
> 
> Introduce the usb4_port_reset() function that performs the DPR
> of a given port. This function follows the CM guide specification 7.3
> 
> Suggested-by: Mario Limonciello <mario.limonciello@amd.com>
> Signed-off-by: Sanath S <Sanath.S@amd.com>
> ---
>  drivers/thunderbolt/switch.c  | 31 ++++++++++++++++++++++++++++
>  drivers/thunderbolt/tb.h      |  2 ++
>  drivers/thunderbolt/tb_regs.h |  1 +
>  drivers/thunderbolt/usb4.c    | 39 +++++++++++++++++++++++++++++++++++
>  4 files changed, 73 insertions(+)
> 
> diff --git a/drivers/thunderbolt/switch.c b/drivers/thunderbolt/switch.c
> index 44e9b09de47a..26ad6cc1ee91 100644
> --- a/drivers/thunderbolt/switch.c
> +++ b/drivers/thunderbolt/switch.c
> @@ -626,6 +626,19 @@ int tb_port_unlock(struct tb_port *port)
>  	return 0;
>  }
>  
> +/**
> + * tb_port_reset() - Reset downstream port
> + * @port: Port to reset
> + *
> + * Helps to reconfigure the USB4 link by resetting the downstream port.
> + *
> + * Return: Returns 0 on success or an error code on failure.
> + */
> +static int tb_port_reset(struct tb_port *port)
> +{
> +	return usb4_port_reset(port);
> +}
> +
>  static int __tb_port_enable(struct tb_port *port, bool enable)
>  {
>  	int ret;
> @@ -1547,6 +1560,24 @@ static void tb_dump_switch(const struct tb *tb, const struct tb_switch *sw)
>  	       regs->__unknown1, regs->__unknown4);
>  }
>  
> +/**
> + * tb_switch_reset_ports() - Reset downstream ports of switch.
> + * @sw: Switch whose ports need to be reset.
> + *
> + * Return: Returns 0 on success or an error code on failure.
> + */
> +int tb_switch_reset_ports(struct tb_switch *sw)
> +{
> +	struct tb_port *port;
> +	int ret = -EINVAL;

Why it returns -EINVAL? What if this is run for non-USB4 router?

> +
> +	tb_switch_for_each_port(sw, port) {
> +		if (tb_port_is_null(port) && port->cap_usb4)
> +			ret = tb_port_reset(port);

Should it stop here and return ret?

> +	}
> +	return ret;
> +}
> +
>  /**
>   * tb_switch_reset() - reconfigure route, enable and send TB_CFG_PKG_RESET
>   * @sw: Switch to reset
> diff --git a/drivers/thunderbolt/tb.h b/drivers/thunderbolt/tb.h
> index e299e53473ae..f2687ec4ac53 100644
> --- a/drivers/thunderbolt/tb.h
> +++ b/drivers/thunderbolt/tb.h
> @@ -797,6 +797,7 @@ void tb_switch_remove(struct tb_switch *sw);
>  void tb_switch_suspend(struct tb_switch *sw, bool runtime);
>  int tb_switch_resume(struct tb_switch *sw);
>  int tb_switch_reset(struct tb_switch *sw);
> +int tb_switch_reset_ports(struct tb_switch *sw);
>  int tb_switch_wait_for_bit(struct tb_switch *sw, u32 offset, u32 bit,
>  			   u32 value, int timeout_msec);
>  void tb_sw_set_unplugged(struct tb_switch *sw);
> @@ -1281,6 +1282,7 @@ struct tb_port *usb4_switch_map_usb3_down(struct tb_switch *sw,
>  int usb4_switch_add_ports(struct tb_switch *sw);
>  void usb4_switch_remove_ports(struct tb_switch *sw);
>  
> +int usb4_port_reset(struct tb_port *port);
>  int usb4_port_unlock(struct tb_port *port);
>  int usb4_port_hotplug_enable(struct tb_port *port);
>  int usb4_port_configure(struct tb_port *port);
> diff --git a/drivers/thunderbolt/tb_regs.h b/drivers/thunderbolt/tb_regs.h
> index 87e4795275fe..d49530bc0d53 100644
> --- a/drivers/thunderbolt/tb_regs.h
> +++ b/drivers/thunderbolt/tb_regs.h
> @@ -389,6 +389,7 @@ struct tb_regs_port_header {
>  #define PORT_CS_18_CSA				BIT(22)
>  #define PORT_CS_18_TIP				BIT(24)
>  #define PORT_CS_19				0x13
> +#define PORT_CS_19_DPR				BIT(0)
>  #define PORT_CS_19_PC				BIT(3)
>  #define PORT_CS_19_PID				BIT(4)
>  #define PORT_CS_19_WOC				BIT(16)
> diff --git a/drivers/thunderbolt/usb4.c b/drivers/thunderbolt/usb4.c
> index 4277733d0021..55f7c163bf84 100644
> --- a/drivers/thunderbolt/usb4.c
> +++ b/drivers/thunderbolt/usb4.c
> @@ -1073,6 +1073,45 @@ void usb4_switch_remove_ports(struct tb_switch *sw)
>  	}
>  }
>  
> +/**
> + * usb4_port_reset() - Reset USB4 downsteam port
> + * @port: USB4 port to reset.
> + *
> + * Helps to reconfigure USB4 link by resetting downstream port.
> + *
> + * Return: Returns 0 on success or an error code on failure.
> + */
> +int usb4_port_reset(struct tb_port *port)
> +{
> +	int ret;
> +	u32 val = 0;

Reverse christmas tree please:

u32 val = 0;
int ret;

> +
> +	ret = tb_port_read(port, &val, TB_CFG_PORT,
> +			port->cap_usb4 + PORT_CS_19, 1);
> +	if (ret)
> +		return ret;
> +
> +	val = val | PORT_CS_19_DPR;
> +	ret = tb_port_write(port, &val, TB_CFG_PORT,
> +			port->cap_usb4 + PORT_CS_19, 1);
> +	if (ret)
> +		return ret;
> +
> +	/* Wait for 10ms after requesting downstream port reset */
> +	msleep(10);

Probably good to add a couple of more ms just in case. Also
usleep_range()? (or fsleep()).

> +
> +	ret = tb_port_read(port, &val, TB_CFG_PORT,
> +			port->cap_usb4 + PORT_CS_19, 1);
> +	if (ret)
> +		return ret;
> +
> +	val &= ~PORT_CS_19_DPR;
> +	ret = tb_port_write(port, &val, TB_CFG_PORT,
> +			port->cap_usb4 + PORT_CS_19, 1);
> +
> +	return ret;
> +}
> +
>  /**
>   * usb4_port_unlock() - Unlock USB4 downstream port
>   * @port: USB4 port to unlock
> -- 
> 2.34.1

Re: [PATCH 1/2] thunderbolt: Introduce tb_switch_reset_ports(), tb_port_reset() and usb4_port_reset()

[Mario Limonciello]

On 12/12/2023 09:27, Mika Westerberg wrote:
> On Tue, Dec 12, 2023 at 07:30:46PM +0530, Sanath S wrote:
>> Introduce the tb_switch_reset_ports() function that resets the
>> downstream ports of a given switch. This helps us reset the USB4
>> links created by boot firmware during the init sequence.
>>
>> Introduce the tb_port_reset() helper function that resets the
>> given port.
>>
>> Introduce the usb4_port_reset() function that performs the DPR
>> of a given port. This function follows the CM guide specification 7.3
>>
>> Suggested-by: Mario Limonciello <mario.limonciello@amd.com>
>> Signed-off-by: Sanath S <Sanath.S@amd.com>
>> ---
>>   drivers/thunderbolt/switch.c  | 31 ++++++++++++++++++++++++++++
>>   drivers/thunderbolt/tb.h      |  2 ++
>>   drivers/thunderbolt/tb_regs.h |  1 +
>>   drivers/thunderbolt/usb4.c    | 39 +++++++++++++++++++++++++++++++++++
>>   4 files changed, 73 insertions(+)
>>
>> diff --git a/drivers/thunderbolt/switch.c b/drivers/thunderbolt/switch.c
>> index 44e9b09de47a..26ad6cc1ee91 100644
>> --- a/drivers/thunderbolt/switch.c
>> +++ b/drivers/thunderbolt/switch.c
>> @@ -626,6 +626,19 @@ int tb_port_unlock(struct tb_port *port)
>>   	return 0;
>>   }
>>   
>> +/**
>> + * tb_port_reset() - Reset downstream port
>> + * @port: Port to reset
>> + *
>> + * Helps to reconfigure the USB4 link by resetting the downstream port.
>> + *
>> + * Return: Returns 0 on success or an error code on failure.
>> + */
>> +static int tb_port_reset(struct tb_port *port)
>> +{
>> +	return usb4_port_reset(port);
>> +}
>> +
>>   static int __tb_port_enable(struct tb_port *port, bool enable)
>>   {
>>   	int ret;
>> @@ -1547,6 +1560,24 @@ static void tb_dump_switch(const struct tb *tb, const struct tb_switch *sw)
>>   	       regs->__unknown1, regs->__unknown4);
>>   }
>>   
>> +/**
>> + * tb_switch_reset_ports() - Reset downstream ports of switch.
>> + * @sw: Switch whose ports need to be reset.
>> + *
>> + * Return: Returns 0 on success or an error code on failure.
>> + */
>> +int tb_switch_reset_ports(struct tb_switch *sw)
>> +{
>> +	struct tb_port *port;
>> +	int ret = -EINVAL;
> 
> Why it returns -EINVAL? What if this is run for non-USB4 router?

This is a good point, but in the non USB4 case (default return) maybe 
it's better to be -ENODEV and in patch 2 be careful about the caller.

> 
>> +
>> +	tb_switch_for_each_port(sw, port) {
>> +		if (tb_port_is_null(port) && port->cap_usb4)
>> +			ret = tb_port_reset(port);
> 
> Should it stop here and return ret?

+1

> 
>> +	}
>> +	return ret;
>> +}
>> +
>>   /**
>>    * tb_switch_reset() - reconfigure route, enable and send TB_CFG_PKG_RESET
>>    * @sw: Switch to reset
>> diff --git a/drivers/thunderbolt/tb.h b/drivers/thunderbolt/tb.h
>> index e299e53473ae..f2687ec4ac53 100644
>> --- a/drivers/thunderbolt/tb.h
>> +++ b/drivers/thunderbolt/tb.h
>> @@ -797,6 +797,7 @@ void tb_switch_remove(struct tb_switch *sw);
>>   void tb_switch_suspend(struct tb_switch *sw, bool runtime);
>>   int tb_switch_resume(struct tb_switch *sw);
>>   int tb_switch_reset(struct tb_switch *sw);
>> +int tb_switch_reset_ports(struct tb_switch *sw);
>>   int tb_switch_wait_for_bit(struct tb_switch *sw, u32 offset, u32 bit,
>>   			   u32 value, int timeout_msec);
>>   void tb_sw_set_unplugged(struct tb_switch *sw);
>> @@ -1281,6 +1282,7 @@ struct tb_port *usb4_switch_map_usb3_down(struct tb_switch *sw,
>>   int usb4_switch_add_ports(struct tb_switch *sw);
>>   void usb4_switch_remove_ports(struct tb_switch *sw);
>>   
>> +int usb4_port_reset(struct tb_port *port);
>>   int usb4_port_unlock(struct tb_port *port);
>>   int usb4_port_hotplug_enable(struct tb_port *port);
>>   int usb4_port_configure(struct tb_port *port);
>> diff --git a/drivers/thunderbolt/tb_regs.h b/drivers/thunderbolt/tb_regs.h
>> index 87e4795275fe..d49530bc0d53 100644
>> --- a/drivers/thunderbolt/tb_regs.h
>> +++ b/drivers/thunderbolt/tb_regs.h
>> @@ -389,6 +389,7 @@ struct tb_regs_port_header {
>>   #define PORT_CS_18_CSA				BIT(22)
>>   #define PORT_CS_18_TIP				BIT(24)
>>   #define PORT_CS_19				0x13
>> +#define PORT_CS_19_DPR				BIT(0)
>>   #define PORT_CS_19_PC				BIT(3)
>>   #define PORT_CS_19_PID				BIT(4)
>>   #define PORT_CS_19_WOC				BIT(16)
>> diff --git a/drivers/thunderbolt/usb4.c b/drivers/thunderbolt/usb4.c
>> index 4277733d0021..55f7c163bf84 100644
>> --- a/drivers/thunderbolt/usb4.c
>> +++ b/drivers/thunderbolt/usb4.c
>> @@ -1073,6 +1073,45 @@ void usb4_switch_remove_ports(struct tb_switch *sw)
>>   	}
>>   }
>>   
>> +/**
>> + * usb4_port_reset() - Reset USB4 downsteam port
>> + * @port: USB4 port to reset.
>> + *
>> + * Helps to reconfigure USB4 link by resetting downstream port.
>> + *
>> + * Return: Returns 0 on success or an error code on failure.
>> + */
>> +int usb4_port_reset(struct tb_port *port)
>> +{
>> +	int ret;
>> +	u32 val = 0;
> 
> Reverse christmas tree please:
> 
> u32 val = 0;
> int ret;
> 
>> +
>> +	ret = tb_port_read(port, &val, TB_CFG_PORT,
>> +			port->cap_usb4 + PORT_CS_19, 1);
>> +	if (ret)
>> +		return ret;
>> +
>> +	val = val | PORT_CS_19_DPR;
>> +	ret = tb_port_write(port, &val, TB_CFG_PORT,
>> +			port->cap_usb4 + PORT_CS_19, 1);
>> +	if (ret)
>> +		return ret;
>> +
>> +	/* Wait for 10ms after requesting downstream port reset */
>> +	msleep(10);
> 
> Probably good to add a couple of more ms just in case. Also
> usleep_range()? (or fsleep()).

Sanath had it at 20 but I had suggested to align to spec.
For the wiggle room maybe usleep_range(10000, 15000)?

> 
>> +
>> +	ret = tb_port_read(port, &val, TB_CFG_PORT,
>> +			port->cap_usb4 + PORT_CS_19, 1);
>> +	if (ret)
>> +		return ret;
>> +
>> +	val &= ~PORT_CS_19_DPR;
>> +	ret = tb_port_write(port, &val, TB_CFG_PORT,
>> +			port->cap_usb4 + PORT_CS_19, 1);
>> +
>> +	return ret;
>> +}
>> +
>>   /**
>>    * usb4_port_unlock() - Unlock USB4 downstream port
>>    * @port: USB4 port to unlock
>> -- 
>> 2.34.1

Re: [PATCH 1/2] thunderbolt: Introduce tb_switch_reset_ports(), tb_port_reset() and usb4_port_reset()

[Mika Westerberg]

On Tue, Dec 12, 2023 at 09:32:03AM -0600, Mario Limonciello wrote:
> On 12/12/2023 09:27, Mika Westerberg wrote:
> > On Tue, Dec 12, 2023 at 07:30:46PM +0530, Sanath S wrote:
> > > Introduce the tb_switch_reset_ports() function that resets the
> > > downstream ports of a given switch. This helps us reset the USB4
> > > links created by boot firmware during the init sequence.
> > > 
> > > Introduce the tb_port_reset() helper function that resets the
> > > given port.
> > > 
> > > Introduce the usb4_port_reset() function that performs the DPR
> > > of a given port. This function follows the CM guide specification 7.3
> > > 
> > > Suggested-by: Mario Limonciello <mario.limonciello@amd.com>
> > > Signed-off-by: Sanath S <Sanath.S@amd.com>
> > > ---
> > >   drivers/thunderbolt/switch.c  | 31 ++++++++++++++++++++++++++++
> > >   drivers/thunderbolt/tb.h      |  2 ++
> > >   drivers/thunderbolt/tb_regs.h |  1 +
> > >   drivers/thunderbolt/usb4.c    | 39 +++++++++++++++++++++++++++++++++++
> > >   4 files changed, 73 insertions(+)
> > > 
> > > diff --git a/drivers/thunderbolt/switch.c b/drivers/thunderbolt/switch.c
> > > index 44e9b09de47a..26ad6cc1ee91 100644
> > > --- a/drivers/thunderbolt/switch.c
> > > +++ b/drivers/thunderbolt/switch.c
> > > @@ -626,6 +626,19 @@ int tb_port_unlock(struct tb_port *port)
> > >   	return 0;
> > >   }
> > > +/**
> > > + * tb_port_reset() - Reset downstream port
> > > + * @port: Port to reset
> > > + *
> > > + * Helps to reconfigure the USB4 link by resetting the downstream port.
> > > + *
> > > + * Return: Returns 0 on success or an error code on failure.
> > > + */
> > > +static int tb_port_reset(struct tb_port *port)
> > > +{
> > > +	return usb4_port_reset(port);
> > > +}
> > > +
> > >   static int __tb_port_enable(struct tb_port *port, bool enable)
> > >   {
> > >   	int ret;
> > > @@ -1547,6 +1560,24 @@ static void tb_dump_switch(const struct tb *tb, const struct tb_switch *sw)
> > >   	       regs->__unknown1, regs->__unknown4);
> > >   }
> > > +/**
> > > + * tb_switch_reset_ports() - Reset downstream ports of switch.
> > > + * @sw: Switch whose ports need to be reset.
> > > + *
> > > + * Return: Returns 0 on success or an error code on failure.
> > > + */
> > > +int tb_switch_reset_ports(struct tb_switch *sw)
> > > +{
> > > +	struct tb_port *port;
> > > +	int ret = -EINVAL;
> > 
> > Why it returns -EINVAL? What if this is run for non-USB4 router?
> 
> This is a good point, but in the non USB4 case (default return) maybe it's
> better to be -ENODEV and in patch 2 be careful about the caller.

Or -EOPNOTSUPP (to be consistent with the rest of the driver). Add this
to the kernel-doc too so that the caller needs to make sure
tb_switch_is_usb4() is called before this one or so.

> 
> > 
> > > +
> > > +	tb_switch_for_each_port(sw, port) {
> > > +		if (tb_port_is_null(port) && port->cap_usb4)
> > > +			ret = tb_port_reset(port);
> > 
> > Should it stop here and return ret?
> 
> +1
> 
> > 
> > > +	}
> > > +	return ret;
> > > +}
> > > +
> > >   /**
> > >    * tb_switch_reset() - reconfigure route, enable and send TB_CFG_PKG_RESET
> > >    * @sw: Switch to reset
> > > diff --git a/drivers/thunderbolt/tb.h b/drivers/thunderbolt/tb.h
> > > index e299e53473ae..f2687ec4ac53 100644
> > > --- a/drivers/thunderbolt/tb.h
> > > +++ b/drivers/thunderbolt/tb.h
> > > @@ -797,6 +797,7 @@ void tb_switch_remove(struct tb_switch *sw);
> > >   void tb_switch_suspend(struct tb_switch *sw, bool runtime);
> > >   int tb_switch_resume(struct tb_switch *sw);
> > >   int tb_switch_reset(struct tb_switch *sw);
> > > +int tb_switch_reset_ports(struct tb_switch *sw);
> > >   int tb_switch_wait_for_bit(struct tb_switch *sw, u32 offset, u32 bit,
> > >   			   u32 value, int timeout_msec);
> > >   void tb_sw_set_unplugged(struct tb_switch *sw);
> > > @@ -1281,6 +1282,7 @@ struct tb_port *usb4_switch_map_usb3_down(struct tb_switch *sw,
> > >   int usb4_switch_add_ports(struct tb_switch *sw);
> > >   void usb4_switch_remove_ports(struct tb_switch *sw);
> > > +int usb4_port_reset(struct tb_port *port);
> > >   int usb4_port_unlock(struct tb_port *port);
> > >   int usb4_port_hotplug_enable(struct tb_port *port);
> > >   int usb4_port_configure(struct tb_port *port);
> > > diff --git a/drivers/thunderbolt/tb_regs.h b/drivers/thunderbolt/tb_regs.h
> > > index 87e4795275fe..d49530bc0d53 100644
> > > --- a/drivers/thunderbolt/tb_regs.h
> > > +++ b/drivers/thunderbolt/tb_regs.h
> > > @@ -389,6 +389,7 @@ struct tb_regs_port_header {
> > >   #define PORT_CS_18_CSA				BIT(22)
> > >   #define PORT_CS_18_TIP				BIT(24)
> > >   #define PORT_CS_19				0x13
> > > +#define PORT_CS_19_DPR				BIT(0)
> > >   #define PORT_CS_19_PC				BIT(3)
> > >   #define PORT_CS_19_PID				BIT(4)
> > >   #define PORT_CS_19_WOC				BIT(16)
> > > diff --git a/drivers/thunderbolt/usb4.c b/drivers/thunderbolt/usb4.c
> > > index 4277733d0021..55f7c163bf84 100644
> > > --- a/drivers/thunderbolt/usb4.c
> > > +++ b/drivers/thunderbolt/usb4.c
> > > @@ -1073,6 +1073,45 @@ void usb4_switch_remove_ports(struct tb_switch *sw)
> > >   	}
> > >   }
> > > +/**
> > > + * usb4_port_reset() - Reset USB4 downsteam port
> > > + * @port: USB4 port to reset.
> > > + *
> > > + * Helps to reconfigure USB4 link by resetting downstream port.
> > > + *
> > > + * Return: Returns 0 on success or an error code on failure.
> > > + */
> > > +int usb4_port_reset(struct tb_port *port)
> > > +{
> > > +	int ret;
> > > +	u32 val = 0;
> > 
> > Reverse christmas tree please:
> > 
> > u32 val = 0;
> > int ret;
> > 
> > > +
> > > +	ret = tb_port_read(port, &val, TB_CFG_PORT,
> > > +			port->cap_usb4 + PORT_CS_19, 1);
> > > +	if (ret)
> > > +		return ret;
> > > +
> > > +	val = val | PORT_CS_19_DPR;
> > > +	ret = tb_port_write(port, &val, TB_CFG_PORT,
> > > +			port->cap_usb4 + PORT_CS_19, 1);
> > > +	if (ret)
> > > +		return ret;
> > > +
> > > +	/* Wait for 10ms after requesting downstream port reset */
> > > +	msleep(10);
> > 
> > Probably good to add a couple of more ms just in case. Also
> > usleep_range()? (or fsleep()).
> 
> Sanath had it at 20 but I had suggested to align to spec.
> For the wiggle room maybe usleep_range(10000, 15000)?

Works for me.

> 
> > 
> > > +
> > > +	ret = tb_port_read(port, &val, TB_CFG_PORT,
> > > +			port->cap_usb4 + PORT_CS_19, 1);
> > > +	if (ret)
> > > +		return ret;
> > > +
> > > +	val &= ~PORT_CS_19_DPR;
> > > +	ret = tb_port_write(port, &val, TB_CFG_PORT,
> > > +			port->cap_usb4 + PORT_CS_19, 1);
> > > +
> > > +	return ret;
> > > +}
> > > +
> > >   /**
> > >    * usb4_port_unlock() - Unlock USB4 downstream port
> > >    * @port: USB4 port to unlock
> > > -- 
> > > 2.34.1