Fixes and improved support for AMD version of Surface Laptop 4

arch/x86/kernel/i8259.c

@@ -1,4 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0
+
+#define pr_fmt(fmt) "i8259: " fmt
+
 #include <linux/linkage.h>
 #include <linux/errno.h>
 #include <linux/signal.h>
@@ -16,6 +19,7 @@
 #include <linux/io.h>
 #include <linux/delay.h>
 #include <linux/pgtable.h>
+#include <linux/dmi.h>
 
 #include <linux/atomic.h>
 #include <asm/timer.h>
@@ -298,11 +302,39 @@ static void unmask_8259A(void)
 	raw_spin_unlock_irqrestore(&i8259A_lock, flags);
 }
 
+/*
+ * DMI table to identify devices with quirky probe behavior. See comment in
+ * probe_8259A() for more details.
+ */
+static const struct dmi_system_id retry_probe_quirk_table[] = {
+	{
+		.ident = "Microsoft Surface Laptop 4 (AMD)",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "Microsoft Corporation"),
+			DMI_MATCH(DMI_PRODUCT_SKU, "Surface_Laptop_4_1952:1953")
+		},
+	},
+	{}
+};
+
 static int probe_8259A(void)
 {
 	unsigned long flags;
 	unsigned char probe_val = ~(1 << PIC_CASCADE_IR);
 	unsigned char new_val;
+	unsigned int i, imax = 1;
+
+	/*
+	 * Some systems have a legacy PIC that doesn't immediately respond
+	 * after boot. We know it's there, we know it should respond and is
+	 * required for proper interrupt handling later on, so let's try a
+	 * couple of times.
+	 */
+	if (dmi_check_system(retry_probe_quirk_table)) {
+		pr_warn("system with broken legacy PIC detected, re-trying multiple times if necessary\n");
+		imax = 10;
+	}
+
 	/*
 	 * Check to see if we have a PIC.
 	 * Mask all except the cascade and read
@@ -312,15 +344,24 @@ static int probe_8259A(void)
 	 */
 	raw_spin_lock_irqsave(&i8259A_lock, flags);
 
-	outb(0xff, PIC_SLAVE_IMR);	/* mask all of 8259A-2 */
-	outb(probe_val, PIC_MASTER_IMR);
-	new_val = inb(PIC_MASTER_IMR);
-	if (new_val != probe_val) {
-		printk(KERN_INFO "Using NULL legacy PIC\n");
+	for (i = 0; i < imax; i++) {
+		outb(0xff, PIC_SLAVE_IMR);	/* mask all of 8259A-2 */
+		outb(probe_val, PIC_MASTER_IMR);
+		new_val = inb(PIC_MASTER_IMR);
+		if (new_val == probe_val)
+			break;
+	}
+
+	if (i == imax) {
+		pr_info("using NULL legacy PIC\n");
 		legacy_pic = &null_legacy_pic;
 	}
 
 	raw_spin_unlock_irqrestore(&i8259A_lock, flags);
+
+	if (imax > 1 && i < imax)
+		pr_info("got legacy PIC after %d tries\n", i + 1);
+
 	return nr_legacy_irqs();
 }
 

drivers/acpi/acpi_apd.c

@@ -226,6 +226,7 @@ static const struct acpi_device_id acpi_apd_device_ids[] = {
 	{ "AMDI0010", APD_ADDR(wt_i2c_desc) },
 	{ "AMD0020", APD_ADDR(cz_uart_desc) },
 	{ "AMDI0020", APD_ADDR(cz_uart_desc) },
+	{ "AMDI0022", APD_ADDR(cz_uart_desc) },
 	{ "AMD0030", },
 	{ "AMD0040", APD_ADDR(fch_misc_desc)},
 	{ "HYGO0010", APD_ADDR(wt_i2c_desc) },

drivers/pinctrl/pinctrl-amd.c

@@ -991,6 +991,7 @@ static int amd_gpio_remove(struct platform_device *pdev)
 static const struct acpi_device_id amd_gpio_acpi_match[] = {
 	{ "AMD0030", 0 },
 	{ "AMDI0030", 0},
+	{ "AMDI0031", 0},
 	{ },
 };
 MODULE_DEVICE_TABLE(acpi, amd_gpio_acpi_match);

drivers/tty/serial/8250/8250_dw.c

@@ -714,6 +714,7 @@ static const struct acpi_device_id dw8250_acpi_match[] = {
 	{ "APMC0D08", 0},
 	{ "AMD0020", 0 },
 	{ "AMDI0020", 0 },
+	{ "AMDI0022", 0 },
 	{ "BRCM2032", 0 },
 	{ "HISI0031", 0 },
 	{ },