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SubjectRe: [2/3] i2c: piix4: fix number of ports on Family 16h Model 30h
On Mon, Jan 29, 2018 at 01:54:19PM +1000, Andrew Cooks wrote:
> 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 Models 30h-3Fh,
>
> Signed-off-by: Andrew Cooks <andrew.cooks@opengear.com>
> ---
> drivers/i2c/busses/i2c-piix4.c | 31 ++++++++++++++++++++++---------
> 1 file changed, 22 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-piix4.c b/drivers/i2c/busses/i2c-piix4.c
> index 89692f4..9763241 100644
> --- a/drivers/i2c/busses/i2c-piix4.c
> +++ b/drivers/i2c/busses/i2c-piix4.c
> @@ -82,6 +82,13 @@
> /* Multi-port constants */
> #define PIIX4_MAX_ADAPTERS 4
>
> +/*
> + * Main adapter port count. At least one (Port 0) plus up to 3 additional
> + * (Ports 2-4)
> + */

This is a bit misleading. Which adapter has only one port ?

> +#define SB800_MAIN_PORTS 4
> +#define HUDSON2_MAIN_PORTS 2 /* HUDSON2, reserves Port 3 and Port 4 */
> +
A tab between define and value might be helpful.
Not sure though why both PIIX4_MAX_ADAPTERS and SB800_MAIN_PORTS
are needed.

> /* SB800 constants */
> #define SB800_PIIX4_SMB_IDX 0xcd6
>
> @@ -800,6 +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;

This variable is never set, only decreased.

>
> static int piix4_add_adapter(struct pci_dev *dev, unsigned short smba,
> bool sb800_main, u8 port, bool notify_imc,
> @@ -856,10 +864,17 @@ static int piix4_add_adapters_sb800(struct pci_dev *dev, unsigned short smba,
> bool notify_imc)
> {
> struct i2c_piix4_adapdata *adapdata;
> - int port;
> + int port, port_count;
> int retval;
>
> - for (port = 0; port < PIIX4_MAX_ADAPTERS; port++) {
> + if (dev->device == PCI_DEVICE_ID_AMD_HUDSON2_SMBUS ||
> + dev->device == PCI_DEVICE_ID_AMD_KERNCZ_SMBUS) {
> + port_count = HUDSON2_MAIN_PORTS;
> + } else {
> + port_count = SB800_MAIN_PORTS;
> + }
> +
> + for (port = 0; port < port_count; port++) {
> retval = piix4_add_adapter(dev, smba, true, port, notify_imc,
> piix4_main_port_names_sb800[port],
> &piix4_main_adapters[port]);
> @@ -872,7 +887,7 @@ static int piix4_add_adapters_sb800(struct pci_dev *dev, unsigned short smba,
> error:
> dev_err(&dev->dev,
> "Error setting up SB800 adapters. Unregistering!\n");
> - while (--port >= 0) {
> + while (--piix4_adapter_count >= 0) {

This is wrong, even if piix4_adapter_count was initialized.

> adapdata = i2c_get_adapdata(piix4_main_adapters[port]);
> if (adapdata->smba) {
> i2c_del_adapter(piix4_main_adapters[port]);
> @@ -993,12 +1008,10 @@ static void piix4_adap_remove(struct i2c_adapter *adap)
>
> static void piix4_remove(struct pci_dev *dev)
> {
> - int port = PIIX4_MAX_ADAPTERS;

A one line change would do it just as well.
int port = piix4_adapter_count;

> -
> - while (--port >= 0) {
> - if (piix4_main_adapters[port]) {
> - piix4_adap_remove(piix4_main_adapters[port]);
> - piix4_main_adapters[port] = NULL;
> + while (--piix4_adapter_count >= 0) {
> + if (piix4_main_adapters[piix4_adapter_count]) {
> + piix4_adap_remove(piix4_main_adapters[piix4_adapter_count]);
> + piix4_main_adapters[piix4_adapter_count] = NULL;
> }
> }
>

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