[PATCH] imx93_frdm: clear and mask TCPC interrupts

[Francesco Valla]

One of the two on-board PTN5110 TCPC USB Power Delivery controller on
the i.MX93 FRDM board shares its interrupt line whith the PCAL6524 power
controller (GPIO3-27). Since the PTN5110 starts after POR with the
interrupts enabled, this can lead to an interrupt storm on OS startup if
only the driver for the PCAL6524 is loaded, because none is servicing
(and clearing) the interrupt requests from the PTN5110.

Maks and clear all interrupts as part uring board initialization; they
can be re-enabled later by a proper OS driver if required.

Co-developed-by: Joseph Guo <qijian.guo at nxp.com>
Signed-off-by: Francesco Valla <francesco at valla.it>
---
Interrupt storms have been observed during the Linux kernel startup on
the i.MX93 FRDM [0], leading to the IRQ functionality being disabled for
the involved IRQ line. Even in case the IRQ line is not disabled,
several thousands of interrupts can be observed:

 94:      55749          0 gpio-vf610  27 Level     1-0022, 2-0050

This has been traced to the interrupt sharing for one of the on-board
PTN5110 TCPC and the PCAL6524 I/O expander. The same behavior was
observed and fixed on the i.MX91 FRDM [1], so the proposed solution
is the same: to mask and clear all PTN5110 interrupts during board
configuration.

With this patch applied, the interrupt line is completely silent on
startup:

 94:          0          0 gpio-vf610  27 Level     1-0022, 2-0050

I added the Co-developed-by tag giving credit to Joseph Guo since the
technical solution is theirs, as developed for the i.MX91 FRDM.

[0] https://lore.kernel.org/all/20251230171548.67289601@windsurf
[1] https://lore.kernel.org/all/aTDyW8Rm1u6hWUuc@lsvm11u0000395.swis.ap-northeast-2.aws.nxp.com
---
 board/freescale/imx93_frdm/imx93_frdm.c | 59 +++++++++++++++++++++++++++++++++
 1 file changed, 59 insertions(+)

diff --git a/board/freescale/imx93_frdm/imx93_frdm.c b/board/freescale/imx93_frdm/imx93_frdm.c
index c436ac6aa4791000c5eaee13f6190ad7d83bdc55..cfbcde2e1a579e9401a3df04011f567e218af6fa 100644
--- a/board/freescale/imx93_frdm/imx93_frdm.c
+++ b/board/freescale/imx93_frdm/imx93_frdm.c
@@ -5,6 +5,7 @@
 
 #include <env.h>
 #include <efi_loader.h>
+#include <i2c.h>
 #include <init.h>
 #include <asm/global_data.h>
 #include <asm/arch/sys_proto.h>
@@ -36,6 +37,62 @@ struct efi_capsule_update_info update_info = {
 };
 #endif /* EFI_HAVE_CAPSULE_SUPPORT */
 
+#define TCPC_ALERT 0x10
+#define TCPC_ALERT_MASK 0x12
+#define TCPC_FAULT_STATUS_MASK 0x15
+
+#define TCPC1_I2C_BUS 2
+#define TCPC1_I2C_ADDR 0x50
+
+/*
+ * Mask all interrupts and clear alert status for the PTN5110 TCPC USB Power
+ * Delivery controller. This is required to avoid an interrupt storm on OS
+ * startup, since the interrupt line for the PTN5110 is shared also by the
+ * PCAL6524 I/O expander.
+ */
+static int clear_pd_alert(void)
+{
+	struct udevice *bus;
+	struct udevice *i2c_dev = NULL;
+	int ret;
+	u8 buffer_0[2] = {0, 0};
+	u8 buffer_1[2] = {0xff, 0xff};
+
+	ret = uclass_get_device_by_seq(UCLASS_I2C, TCPC1_I2C_BUS, &bus);
+	if (ret) {
+		printf("Failed to get I2C bus %d\n", TCPC1_I2C_BUS);
+		return ret;
+	}
+
+	ret = dm_i2c_probe(bus, TCPC1_I2C_ADDR, 0, &i2c_dev);
+	if (ret) {
+		printf("Can't find USB PD device at 0x%02x\n", TCPC1_I2C_ADDR);
+		return ret;
+	}
+
+	/* Mask all alert status*/
+	ret = dm_i2c_write(i2c_dev, TCPC_ALERT_MASK, buffer_0, 2);
+	if (ret) {
+		printf("%s dm_i2c_write failed: %d\n", __func__, ret);
+		return ret;
+	}
+
+	ret = dm_i2c_write(i2c_dev, TCPC_FAULT_STATUS_MASK, buffer_0, 2);
+	if (ret) {
+		printf("%s dm_i2c_write failed: %d\n", __func__, ret);
+		return ret;
+	}
+
+	/* Clear active alerts */
+	ret = dm_i2c_write(i2c_dev, TCPC_ALERT, buffer_1, 2);
+	if (ret) {
+		printf("%s dm_i2c_write failed: %d\n", __func__, ret);
+		return ret;
+	}
+
+	return 0;
+}
+
 int board_early_init_f(void)
 {
 	return 0;
@@ -61,5 +118,7 @@ int board_late_init(void)
 		env_set_ulong("dofastboot", 1);
 	}
 
+	clear_pd_alert();
+
 	return 0;
 }

---
base-commit: eb18217b63b79dfcec704d420fcc61e77397c88f
change-id: 20260102-imx93_frdm_tcpc_fix-53549c36b7d7

Best regards,
-- 
Francesco Valla <francesco at valla.it>