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authorArd Biesheuvel <ard.biesheuvel@linaro.org>2017-05-19 09:56:40 +0100
committerWolfram Sang <wsa@the-dreams.de>2017-05-19 14:36:24 +0200
commit9d6408433019bfae15e2d0d5f4498c4ff70b86c0 (patch)
tree7475c97c5a420f29f4f867ddf6256a9dba75d7aa /drivers
parent8b4822de59d5d9919b9b045183a36c673ce20b73 (diff)
downloadlinux-9d6408433019bfae15e2d0d5f4498c4ff70b86c0.tar.bz2
i2c: designware: don't infer timings described by ACPI from clock rate
Commit bd698d24b1b57 ("i2c: designware: Get selected speed mode sda-hold-time via ACPI") updated the logic that reads the timing parameters for various I2C bus rates from the DSDT, to only read the timing parameters for the currently selected mode. This causes a WARN_ON() splat on platforms that legally omit the clock frequency from the ACPI description, because in the new situation, the core I2C designware driver still accesses the fields in the driver struct that we no longer populate, and proceeds to calculate them from the clock frequency. Since the clock frequency is unspecified, the driver complains loudly using a WARN_ON(). So revert back to the old situation, where the struct fields for all timings are populated, but retain the new logic which chooses the SDA hold time from the timing mode that is currently in use. Fixes: bd698d24b1b57 ("i2c: designware: Get selected speed mode ...") Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Reported-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Acked-by: Jarkko Nikula <jarkko.nikula@linux.intel.com> Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/i2c/busses/i2c-designware-platdrv.c18
1 files changed, 10 insertions, 8 deletions
diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
index f2acd4b6bf01..6283b99d2b17 100644
--- a/drivers/i2c/busses/i2c-designware-platdrv.c
+++ b/drivers/i2c/busses/i2c-designware-platdrv.c
@@ -96,6 +96,7 @@ static int dw_i2c_acpi_configure(struct platform_device *pdev)
struct dw_i2c_dev *dev = platform_get_drvdata(pdev);
acpi_handle handle = ACPI_HANDLE(&pdev->dev);
const struct acpi_device_id *id;
+ u32 ss_ht, fp_ht, hs_ht, fs_ht;
struct acpi_device *adev;
const char *uid;
@@ -107,23 +108,24 @@ static int dw_i2c_acpi_configure(struct platform_device *pdev)
* 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, &ss_ht);
+ dw_i2c_acpi_params(pdev, "FPCN", &dev->fp_hcnt, &dev->fp_lcnt, &fp_ht);
+ dw_i2c_acpi_params(pdev, "HSCN", &dev->hs_hcnt, &dev->hs_lcnt, &hs_ht);
+ dw_i2c_acpi_params(pdev, "FMCN", &dev->fs_hcnt, &dev->fs_lcnt, &fs_ht);
+
switch (dev->clk_freq) {
case 100000:
- dw_i2c_acpi_params(pdev, "SSCN", &dev->ss_hcnt, &dev->ss_lcnt,
- &dev->sda_hold_time);
+ dev->sda_hold_time = ss_ht;
break;
case 1000000:
- dw_i2c_acpi_params(pdev, "FPCN", &dev->fp_hcnt, &dev->fp_lcnt,
- &dev->sda_hold_time);
+ dev->sda_hold_time = fp_ht;
break;
case 3400000:
- dw_i2c_acpi_params(pdev, "HSCN", &dev->hs_hcnt, &dev->hs_lcnt,
- &dev->sda_hold_time);
+ dev->sda_hold_time = hs_ht;
break;
case 400000:
default:
- dw_i2c_acpi_params(pdev, "FMCN", &dev->fs_hcnt, &dev->fs_lcnt,
- &dev->sda_hold_time);
+ dev->sda_hold_time = fs_ht;
break;
}