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Subject[PATCH v5 2/3] i2c: piix4: Fix probing of reserved ports on AMD Family 16h Model 30h
Prevent bus timeouts and resets on Family 16h Model 30h by not probing
reserved Ports 3 and 4.

According to the AMD BIOS and Kernel Developer's Guides (BKDG), Port 3
and Port 4 are reserved on the following devices:
- Family 15h Model 60h-6Fh
- Family 15h Model 70h-7Fh
- Family 16h Model 30h-3Fh

Based on earlier work by Andrew Cooks.

Reported-by: Andrew Cooks <andrew.cooks@opengear.com>
Signed-off-by: Jean Delvare <jdelvare@suse.de>
---
Changes since v4:
* Fix subject line
* Drop local variable port_count, use piix4_adapter_count
everywhere to represent the maximum number of main SMBus ports
* Exclude early Hudson2 implementations from this change

drivers/i2c/busses/i2c-piix4.c | 16 +++++++++++++---
1 file changed, 13 insertions(+), 3 deletions(-)

--- linux-5.2.orig/drivers/i2c/busses/i2c-piix4.c 2019-08-02 14:08:17.003820098 +0200
+++ linux-5.2/drivers/i2c/busses/i2c-piix4.c 2019-08-02 14:15:38.284423549 +0200
@@ -72,7 +72,8 @@
#define PIIX4_BLOCK_DATA 0x14

/* Multi-port constants */
-#define PIIX4_MAX_ADAPTERS 4
+#define PIIX4_MAX_ADAPTERS 4
+#define HUDSON2_MAIN_PORTS 2 /* HUDSON2, KERNCZ reserves ports 3, 4 */

/* SB800 constants */
#define SB800_PIIX4_SMB_IDX 0xcd6
@@ -806,6 +807,7 @@ MODULE_DEVICE_TABLE (pci, piix4_ids);

static struct i2c_adapter *piix4_main_adapters[PIIX4_MAX_ADAPTERS];
static struct i2c_adapter *piix4_aux_adapter;
+static int piix4_adapter_count;

static int piix4_add_adapter(struct pci_dev *dev, unsigned short smba,
bool sb800_main, u8 port, bool notify_imc,
@@ -865,7 +867,15 @@ static int piix4_add_adapters_sb800(stru
int port;
int retval;

- for (port = 0; port < PIIX4_MAX_ADAPTERS; port++) {
+ if (dev->device == PCI_DEVICE_ID_AMD_KERNCZ_SMBUS ||
+ (dev->device == PCI_DEVICE_ID_AMD_HUDSON2_SMBUS &&
+ dev->revision >= 0x1F)) {
+ piix4_adapter_count = HUDSON2_MAIN_PORTS;
+ } else {
+ piix4_adapter_count = PIIX4_MAX_ADAPTERS;
+ }
+
+ for (port = 0; port < piix4_adapter_count; port++) {
retval = piix4_add_adapter(dev, smba, true, port, notify_imc,
piix4_main_port_names_sb800[port],
&piix4_main_adapters[port]);
@@ -987,7 +997,7 @@ static void piix4_adap_remove(struct i2c

static void piix4_remove(struct pci_dev *dev)
{
- int port = PIIX4_MAX_ADAPTERS;
+ int port = piix4_adapter_count;

while (--port >= 0) {
if (piix4_main_adapters[port]) {
--
Jean Delvare
SUSE L3 Support

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