Commit bd698d24 authored by chin.yew.tan@intel.com's avatar chin.yew.tan@intel.com Committed by Wolfram Sang

i2c: designware: Get selected speed mode sda-hold-time via ACPI

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: default avatarTan Chin Yew <chin.yew.tan@intel.com>
Reviewed-by: default avatarAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: default avatarJarkko Nikula <jarkko.nikula@linux.intel.com>
Signed-off-by: default avatarWolfram Sang <wsa@the-dreams.de>
parent 2a03d499
...@@ -85,8 +85,7 @@ static void dw_i2c_acpi_params(struct platform_device *pdev, char method[], ...@@ -85,8 +85,7 @@ static void dw_i2c_acpi_params(struct platform_device *pdev, char method[],
*hcnt = (u16)objs[0].integer.value; *hcnt = (u16)objs[0].integer.value;
*lcnt = (u16)objs[1].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); kfree(buf.pointer);
...@@ -105,14 +104,28 @@ static int dw_i2c_acpi_configure(struct platform_device *pdev) ...@@ -105,14 +104,28 @@ static int dw_i2c_acpi_configure(struct platform_device *pdev)
dev->rx_fifo_depth = 32; dev->rx_fifo_depth = 32;
/* /*
* Try to get SDA hold time and *CNT values from an ACPI method if * Try to get SDA hold time and *CNT values from an ACPI method for
* it exists for both supported speed modes. * selected speed modes.
*/ */
dw_i2c_acpi_params(pdev, "SSCN", &dev->ss_hcnt, &dev->ss_lcnt, NULL); switch (dev->clk_freq) {
dw_i2c_acpi_params(pdev, "FMCN", &dev->fs_hcnt, &dev->fs_lcnt, case 100000:
&dev->sda_hold_time); dw_i2c_acpi_params(pdev, "SSCN", &dev->ss_hcnt, &dev->ss_lcnt,
dw_i2c_acpi_params(pdev, "FPCN", &dev->fp_hcnt, &dev->fp_lcnt, NULL); &dev->sda_hold_time);
dw_i2c_acpi_params(pdev, "HSCN", &dev->hs_hcnt, &dev->hs_lcnt, NULL); 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); id = acpi_match_device(pdev->dev.driver->acpi_match_table, &pdev->dev);
if (id && id->driver_data) if (id && id->driver_data)
......
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