On Tue, 2017-03-28 at 16:48 +0800, Tan Chin Yew wrote:
> Sda-hold-time is an important parameter for tuning i2c to meet the
> electrical specification especially for high speed. I2C with incorrect
> sda-hold-time may cause lost arbitration error. Instead of loading all
> speed mode settings, only selected speed mode settings are loaded.
>
> Signed-off-by: Tan Chin Yew <chin.yew.tan@xxxxxxxxx>
Looks good to me:
Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
> ---
> drivers/i2c/busses/i2c-designware-platdrv.c | 31
> ++++++++++++++++++++---------
> 1 file changed, 22 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c
> b/drivers/i2c/busses/i2c-designware-platdrv.c
> index a597ba32..5a4eb6b 100644
> --- a/drivers/i2c/busses/i2c-designware-platdrv.c
> +++ b/drivers/i2c/busses/i2c-designware-platdrv.c
> @@ -85,8 +85,7 @@ static void dw_i2c_acpi_params(struct
> platform_device *pdev, char method[],
>
> *hcnt = (u16)objs[0].integer.value;
> *lcnt = (u16)objs[1].integer.value;
> - if (sda_hold)
> - *sda_hold = (u32)objs[2].integer.value;
> + *sda_hold = (u32)objs[2].integer.value;
> }
>
> kfree(buf.pointer);
> @@ -105,14 +104,28 @@ static int dw_i2c_acpi_configure(struct
> platform_device *pdev)
> dev->rx_fifo_depth = 32;
>
> /*
> - * Try to get SDA hold time and *CNT values from an ACPI
> method if
> - * it exists for both supported speed modes.
> + * Try to get SDA hold time and *CNT values from an ACPI
> method for
> + * selected speed modes.
> */
> - dw_i2c_acpi_params(pdev, "SSCN", &dev->ss_hcnt, &dev-
> >ss_lcnt, NULL);
> - dw_i2c_acpi_params(pdev, "FMCN", &dev->fs_hcnt, &dev-
> >fs_lcnt,
> - &dev->sda_hold_time);
> - dw_i2c_acpi_params(pdev, "FPCN", &dev->fp_hcnt, &dev-
> >fp_lcnt, NULL);
> - dw_i2c_acpi_params(pdev, "HSCN", &dev->hs_hcnt, &dev-
> >hs_lcnt, NULL);
> + switch (dev->clk_freq) {
> + case 100000:
> + dw_i2c_acpi_params(pdev, "SSCN", &dev->ss_hcnt, &dev-
> >ss_lcnt,
> + &dev->sda_hold_time);
> + break;
> + case 1000000:
> + dw_i2c_acpi_params(pdev, "FPCN", &dev->fp_hcnt, &dev-
> >fp_lcnt,
> + &dev->sda_hold_time);
> + break;
> + case 3400000:
> + dw_i2c_acpi_params(pdev, "HSCN", &dev->hs_hcnt, &dev-
> >hs_lcnt,
> + &dev->sda_hold_time);
> + break;
> + case 400000:
> + default:
> + dw_i2c_acpi_params(pdev, "FMCN", &dev->fs_hcnt, &dev-
> >fs_lcnt,
> + &dev->sda_hold_time);
> + break;
> + }
>
> id = acpi_match_device(pdev->dev.driver->acpi_match_table,
> &pdev->dev);
> if (id && id->driver_data)
--
Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Intel Finland Oy
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