From: Tan Chin Yew <chin.yew.tan@xxxxxxxxx>
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. Now, the driver is able to
get sda-hold-time for all the speed supported.
Signed-off-by: Tan Chin Yew <chin.yew.tan@xxxxxxxxx>
---
drivers/i2c/busses/i2c-designware-platdrv.c | 27 ++++++++++++++++++++-------
1 file changed, 20 insertions(+), 7 deletions(-)
diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
index 6ce4313..aa33088 100644
--- a/drivers/i2c/busses/i2c-designware-platdrv.c
+++ b/drivers/i2c/busses/i2c-designware-platdrv.c
@@ -101,15 +101,28 @@ 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,
+ switch (dev->clk_freq) {
+ case 100000:
+ dw_i2c_acpi_params(pdev, "SSCN", &dev->ss_hcnt, &dev->ss_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);
-
+ 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;
+ 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)
dev->accessor_flags |= (u32)id->driver_data;
--
1.9.1
--
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