Re: [PATCH 1/2] thunderbolt: Introduce tb_switch_reset_ports(), tb_port_reset() and usb4_port_reset()
From: Mario Limonciello
Date: Tue Dec 12 2023 - 10:32:17 EST
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@xxxxxxx>
Signed-off-by: Sanath S <Sanath.S@xxxxxxx>
---
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