Re: [PATCH] i2c: designware: Do not require clock when SSCN and FFCN are provided

From	Mika Westerberg <mika.westerberg@linux.intel.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH] i2c: designware: Do not require clock when SSCN and FFCN are provided
Date	2015-12-16 15:30 +0100
Message-ID	<qGlfA-2SD-13@gated-at.bofh.it> (permalink)
References	<qG6qf-1QP-23@gated-at.bofh.it> <qGgSB-8tQ-3@gated-at.bofh.it> <qGl5U-2NG-15@gated-at.bofh.it>
Organization	Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo

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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.
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Thread

[PATCH] i2c: designware: Do not require clock when SSCN and FFCN are provided Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com> - 2015-12-15 23:40 +0100
  Re: [PATCH] i2c: designware: Do not require clock when SSCN and FFCN  are provided Mika Westerberg <mika.westerberg@linux.intel.com> - 2015-12-16 10:50 +0100
    Re: [PATCH] i2c: designware: Do not require clock when SSCN and FFCN  are provided Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com> - 2015-12-16 15:20 +0100
      Re: [PATCH] i2c: designware: Do not require clock when SSCN and FFCN  are provided Mika Westerberg <mika.westerberg@linux.intel.com> - 2015-12-16 15:30 +0100
        Re: [PATCH] i2c: designware: Do not require clock when SSCN and FFCN  are provided Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com> - 2015-12-16 15:50 +0100
          Re: [PATCH] i2c: designware: Do not require clock when SSCN and FFCN  are provided Mika Westerberg <mika.westerberg@linux.intel.com> - 2015-12-16 16:10 +0100
  Re: [PATCH] i2c: designware: Do not require clock when SSCN and FFCN  are provided Loc Ho <lho@apm.com> - 2015-12-17 02:00 +0100

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