Fix accesses to IT8792E

If IT8792E or a compatible chip such as IT8795 (which has the same chip ID,
0x8733) resides at SIO address 0x4e/0x4f, and another Super-IO chip is at
SIO address 0x2e/0x2f, the IT8792E causes a cycle decode problem when exiting
its configuration mode. This can result in access errors for both chips, and
may result in system hangs.

Never exit configuration mode for IT8792E to avoid the problem.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>

diff --git a/it87.c b/it87.c
index 8fb14b9d523998b743831ca09c560af85f0a1d74..1ca0d149add81ab2036f3e60c296ed2d87986f1f 100644 (file)
--- a/it87.c
+++ b/it87.c
@@ -89,13 +89,7 @@ static unsigned short force_id;
 module_param(force_id, ushort, 0);
 MODULE_PARM_DESC(force_id, "Override the detected device ID");
 
-static unsigned short blacklist = 1;
-module_param(blacklist, ushort, 0);
-MODULE_PARM_DESC(blacklist,
-                "Enable/disable blacklist (1=enable, 0=disable, default 1)");
-
 static struct platform_device *it87_pdev[2];
-static bool it87_sio4e_broken;
 #ifdef __IT87_USE_ACPI_MUTEX
 static acpi_handle it87_acpi_sio_handle;
 static char *it87_acpi_sio_mutex;
@@ -127,12 +121,6 @@ static inline int superio_inb(int ioreg, int reg)
 
        outb(reg, ioreg);
        val = inb(ioreg + 1);
-       if (it87_sio4e_broken && ioreg == 0x4e && val == 0xff) {
-               __superio_enter(ioreg);
-               outb(reg, ioreg);
-               val = inb(ioreg + 1);
-               pr_warn("Retry access 0x4e:0x%x -> 0x%x\n", reg, val);
-       }
 
        return val;
 }
@@ -184,9 +172,9 @@ error:
        return -EBUSY;
 }
 
-static inline void superio_exit(int ioreg)
+static inline void superio_exit(int ioreg, bool doexit)
 {
-       if (!it87_sio4e_broken || ioreg != 0x4e) {
+       if (doexit) {
                outb(0x02, ioreg);
                outb(0x02, ioreg + 1);
        }
@@ -2798,9 +2786,10 @@ static const struct attribute_group it87_group_auto_pwm = {
 static int __init it87_find(int sioaddr, unsigned short *address,
                            struct it87_sio_data *sio_data)
 {
-       int err;
-       u16 chip_type;
        const struct it87_devices *config;
+       bool doexit = true;
+       u16 chip_type;
+       int err;
 
        err = superio_enter(sioaddr);
        if (err)
@@ -2842,6 +2831,13 @@ static int __init it87_find(int sioaddr, unsigned short *address,
                break;
        case IT8792E_DEVID:
                sio_data->type = it8792;
+               /*
+                * Disabling configuration mode on IT8792E can result in system
+                * hang-ups and access failures to the Super-IO chip at the
+                * second SIO address. Never exit configuration mode on this
+                * chip to avoid the problem.
+                */
+               doexit = false;
                break;
        case IT8771E_DEVID:
                sio_data->type = it8771;
@@ -3393,7 +3389,7 @@ static int __init it87_find(int sioaddr, unsigned short *address,
                pr_info("Beeping is supported\n");
 
 exit:
-       superio_exit(sioaddr);
+       superio_exit(sioaddr, doexit);
        return err;
 }
 
@@ -3851,18 +3847,15 @@ exit_device_put:
 }
 
 struct it87_dmi_data {
-       bool sio4e_broken;      /* SIO accesses @ 0x4e are broken       */
        char *sio_mutex;        /* SIO ACPI mutex                       */
        u8 skip_pwm;            /* pwm channels to skip for this board  */
 };
 
 /*
  * On Gigabyte AB350 and AX370 boards, accesses to the Super-IO chip
- * at address 0x4e/0x4f can result in a system hang.
- * Accesses to address 0x2e/0x2f need to be mutex protected.
+ * at address 0x2e/0x2f need to be mutex protected.
  */
 static struct it87_dmi_data gigabyte_ab350_gaming = {
-       .sio4e_broken = true,
        .sio_mutex = "\\_SB.PCI0.SBRG.SIO1.MUT0",
 };
 
@@ -3938,7 +3931,6 @@ static int __init sm_it87_init(void)
                dmi_data = dmi->driver_data;
 
        if (dmi_data) {
-               it87_sio4e_broken = dmi_data->sio4e_broken;
 #ifdef __IT87_USE_ACPI_MUTEX
                if (dmi_data->sio_mutex) {
                        static acpi_status status;
@@ -3962,12 +3954,6 @@ static int __init sm_it87_init(void)
                return err;
 
        for (i = 0; i < ARRAY_SIZE(sioaddr); i++) {
-               /*
-                * Accessing the second Super-IO chip can result in board
-                * hangs. Disable until we figure out what is going on.
-                */
-               if (blacklist && it87_sio4e_broken && sioaddr[i] == 0x4e)
-                       continue;
                memset(&sio_data, 0, sizeof(struct it87_sio_data));
                isa_address = 0;
                err = it87_find(sioaddr[i], &isa_address, &sio_data);