On Wed, Feb 15, 2012 at 03:36:49PM +0100, Alexander Stein wrote:
> It was observed the Host Clock Divider was not written by the driver. It
> was still set to (default) 0, if not already set by BIOS, which caused
> garbage on SMBus.
> This driver adds 2 parameters which are used to calculate the divider
> appropriately. This new divider is only applied if the clock divider is
> still default 0.
>
> Signed-off-by: Alexander Stein <alexander.stein@xxxxxxxxxxxxxxxxxxxxx>
> Tested-by: Adam Pribyl <pribyl@xxxxxxxxxxx>
> ---
I don't know the hardware: Can it have multiple SmBusses? Then, a module
parameter would force all of them to the selected mode. Do you really
need the parameter? Maybe defaulting to 100Kbps is sane enough?
@Jean: Is this an embedded driver? :)
> Changes in v2:
> * HSTCLK register is 16 Bit, not 8 Bit. Thanks to Adam for detecting
>
> drivers/i2c/busses/i2c-isch.c | 12 ++++++++++++
> 1 files changed, 12 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-isch.c b/drivers/i2c/busses/i2c-isch.c
> index 6561d27..bdfddf8 100644
> --- a/drivers/i2c/busses/i2c-isch.c
> +++ b/drivers/i2c/busses/i2c-isch.c
> @@ -40,6 +40,7 @@
> /* SCH SMBus address offsets */
> #define SMBHSTCNT (0 + sch_smba)
> #define SMBHSTSTS (1 + sch_smba)
> +#define SMBHSTCLK (2 + sch_smba)
> #define SMBHSTADD (4 + sch_smba) /* TSA */
> #define SMBHSTCMD (5 + sch_smba)
> #define SMBHSTDAT0 (6 + sch_smba)
> @@ -58,6 +59,8 @@
>
> static unsigned short sch_smba;
> static struct i2c_adapter sch_adapter;
> +static int smbus_speed = 100; /* SMBus bus speed in Kbps */
> +static int backbone_speed = 33000; /* backbone speed in KHz */
>
> /*
> * Start the i2c transaction -- the i2c_access will prepare the transaction
> @@ -156,6 +159,13 @@ static s32 sch_access(struct i2c_adapter *adap, u16 addr,
> dev_dbg(&sch_adapter.dev, "SMBus busy (%02x)\n", temp);
> return -EAGAIN;
> }
> + temp = inw(SMBHSTCLK);
> + if (!temp) {
> + dev_notice(&sch_adapter.dev, "clock divider unitialized. Setting module defaults\n");
> + dev_dbg(&sch_adapter.dev, "access speed: %d KHz\n", smbus_speed);
> + outw((backbone_speed / 4) / smbus_speed, SMBHSTCLK);
> + }
> +
> dev_dbg(&sch_adapter.dev, "access size: %d %s\n", size,
> (read_write)?"READ":"WRITE");
> switch (size) {
> @@ -312,3 +322,5 @@ MODULE_AUTHOR("Jacob Pan <jacob.jun.pan@xxxxxxxxx>");
> MODULE_DESCRIPTION("Intel SCH SMBus driver");
> MODULE_LICENSE("GPL");
> MODULE_ALIAS("platform:isch_smbus");
> +module_param(smbus_speed, int, (S_IRUSR | S_IWUSR));
> +module_param(backbone_speed, int, (S_IRUSR | S_IWUSR));
> --
> 1.7.3.4
>
Regards,
Wolfram
--
Pengutronix e.K. | Wolfram Sang |
Industrial Linux Solutions | http://www.pengutronix.de/ |
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