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Groups > linux.kernel > #1610417 > unrolled thread
| Started by | Tan Chin Yew <chin.yew.tan@intel.com> |
|---|---|
| First post | 2017-03-28 10:50 +0200 |
| Last post | 2017-03-31 14:20 +0200 |
| Articles | 3 — 3 participants |
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[PATCH] i2c: designware: Get selected speed mode sda-hold-time via ACPI Tan Chin Yew <chin.yew.tan@intel.com> - 2017-03-28 10:50 +0200
Re: [PATCH] i2c: designware: Get selected speed mode sda-hold-time via ACPI Andy Shevchenko <andriy.shevchenko@linux.intel.com> - 2017-03-28 11:30 +0200
Re: [PATCH] i2c: designware: Get selected speed mode sda-hold-time via ACPI Jarkko Nikula <jarkko.nikula@linux.intel.com> - 2017-03-31 14:20 +0200
| From | Tan Chin Yew <chin.yew.tan@intel.com> |
|---|---|
| Date | 2017-03-28 10:50 +0200 |
| Subject | [PATCH] i2c: designware: Get selected speed mode sda-hold-time via ACPI |
| Message-ID | <tpUZb-4Zu-1@gated-at.bofh.it> |
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@intel.com>
---
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)
--
1.9.1
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| From | Andy Shevchenko <andriy.shevchenko@linux.intel.com> |
|---|---|
| Date | 2017-03-28 11:30 +0200 |
| Subject | Re: [PATCH] i2c: designware: Get selected speed mode sda-hold-time via ACPI |
| Message-ID | <tpVBT-5sY-7@gated-at.bofh.it> |
| In reply to | #1610417 |
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@intel.com>
Looks good to me:
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> ---
> 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@linux.intel.com>
Intel Finland Oy
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| From | Jarkko Nikula <jarkko.nikula@linux.intel.com> |
|---|---|
| Date | 2017-03-31 14:20 +0200 |
| Subject | Re: [PATCH] i2c: designware: Get selected speed mode sda-hold-time via ACPI |
| Message-ID | <tr3H4-4uB-23@gated-at.bofh.it> |
| In reply to | #1610463 |
On 03/28/2017 12:13 PM, Andy Shevchenko wrote: > 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@intel.com> > > > Looks good to me: > > Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> > Acked-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
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