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>

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)