diff options
| author | chin.yew.tan@intel.com <chin.yew.tan@intel.com> | 2017-03-28 16:48:02 +0800 |
|---|---|---|
| committer | Wolfram Sang <wsa@the-dreams.de> | 2017-04-19 20:54:21 +0200 |
| commit | bd698d24b1b5790d0a22d44a0705dabd47235ad4 (patch) | |
| tree | e1b48b9bc2e8485945b759b16a48ba015f94f8fc /drivers/i2c | |
| parent | 2a03d49922fa2b89ceaa7d14b657c8a8e6bc7000 (diff) | |
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: Tan Chin Yew <chin.yew.tan@intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Diffstat (limited to 'drivers/i2c')
| -rw-r--r-- | drivers/i2c/busses/i2c-designware-platdrv.c | 31 |
1 files changed, 22 insertions, 9 deletions
diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c index a597ba32de7e..5a4eb6b6bd92 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) |