Messages in this thread | | | Subject | Re: [PATCH] i2c: designware: Do not require clock when SSCN and FFCN are provided | From | Suravee Suthikulpanit <> | Date | Wed, 16 Dec 2015 08:44:34 -0600 |
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On 12/16/2015 08:28 AM, Mika Westerberg wrote: > On Wed, Dec 16, 2015 at 08:11:12AM -0600, Suravee Suthikulpanit wrote: >>> The clk framework should work fine if the returned clock is NULL (which >>> I think is your case). >>> >>> The driver gates clocks when the device is suspended and on Intel LPSS >>> there actually is a clock that gets gated. >>> >>>> [..] >>>> @@ -203,13 +223,11 @@ static int dw_i2c_plat_probe(struct platform_device *pdev) >>>> dev->master_cfg = DW_IC_CON_MASTER | DW_IC_CON_SLAVE_DISABLE | >>>> DW_IC_CON_RESTART_EN | DW_IC_CON_SPEED_FAST; >>>> >>>> - dev->clk = devm_clk_get(&pdev->dev, NULL); >>>> - dev->get_clk_rate_khz = i2c_dw_get_clk_rate_khz; >>>> - if (IS_ERR(dev->clk)) >>>> - return PTR_ERR(dev->clk); >> >> Actually, if we don't provide the clock (which is the case for ACPI), this >> would also return and cause the probing to fail. > > Indeed it seems that when you have CONFIG_COMMON_CLK selected the clock > framework starts returning errors if the clock is not found. > > Since we need the clock for Intel LPSS I2C host controllers (and they > may have *CNT methods), I think you just need to provide the clock for > AMD I2C host controller in similar way than we do in > drivers/acpi/acpi_lpss.c.
I am trying to avoid having to hard-coded clock frequency value in the driver. Would it be alright to not return w/ error, and just do the following?
dev->clk = devm_clk_get(&pdev->dev, NULL); if (!IS_ERR(dev->clk)) dev->get_clk_rate_khz = i2c_dw_get_clk_rate_khz;
This should work for the Intel case when clock is also provided.
Thanks, Suravee
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