linux-kernel - Re: [PATCH v2 1/2] clk: qcom: gcc-msm8960: add child devices support.

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Date:	Fri, 30 Jan 2015 13:16:36 -0800
From:	Stephen Boyd <sboyd@...eaurora.org>
To:	Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
	Bjorn Andersson <bjorn@...o.se>
CC:	Mike Turquette <mturquette@...aro.org>,
	Rob Herring <robh+dt@...nel.org>,
	Kumar Gala <galak@...eaurora.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	linux-arm-msm <linux-arm-msm@...r.kernel.org>,
	edubezval@...il.com, nrajan@...eaurora.com,
	Arnd Bergmann <arnd@...db.de>
Subject: Re: [PATCH v2 1/2] clk: qcom: gcc-msm8960: add child devices support.

On 01/30/15 10:06, Srinivas Kandagatla wrote:
>
>
> On 30/01/15 16:57, Bjorn Andersson wrote:
>> On Fri, Jan 30, 2015 at 2:17 AM, Srinivas Kandagatla
>> <srinivas.kandagatla@...aro.org> wrote:
>>> This patch adds support to add child devices to gcc as some of the
>>> registers mapped by gcc are used by drivers like thermal sensors.
>>>
>>> Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
>>> ---
>>>   drivers/clk/qcom/gcc-msm8960.c | 10 +++++++++-
>>>   1 file changed, 9 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/clk/qcom/gcc-msm8960.c
>>> b/drivers/clk/qcom/gcc-msm8960.c
>>> index 0cd3e26..3ba77c5 100644
>>> --- a/drivers/clk/qcom/gcc-msm8960.c
>>> +++ b/drivers/clk/qcom/gcc-msm8960.c
>>> @@ -15,6 +15,7 @@
>>>   #include <linux/bitops.h>
>>>   #include <linux/err.h>
>>>   #include <linux/platform_device.h>
>>> +#include <linux/of_platform.h>
>>>   #include <linux/module.h>
>>>   #include <linux/of.h>
>>>   #include <linux/of_device.h>
>>> @@ -3658,6 +3659,7 @@ static int gcc_msm8960_probe(struct
>>> platform_device *pdev)
>>>          struct clk *clk;
>>>          struct device *dev = &pdev->dev;
>>>          const struct of_device_id *match;
>>> +       int ret;
>>>
>>>          match = of_match_device(gcc_msm8960_match_table, &pdev->dev);
>>>          if (!match)
>>> @@ -3677,12 +3679,18 @@ static int gcc_msm8960_probe(struct
>>> platform_device *pdev)
>>>          if (IS_ERR(clk))
>>>                  return PTR_ERR(clk);
>>>
>>> -       return qcom_cc_probe(pdev, match->data);
>>> +       ret = qcom_cc_probe(pdev, match->data);
>>> +       if (ret)
>>> +               return ret;
>>> +
>>> +       return of_platform_populate(pdev->dev.of_node, NULL, NULL,
>>> &pdev->dev);
>>
>> How about calling of_syscon_register() instead? That would give us a
>> handle to a regmap that can be consumed in e.g. the thermal driver.
>
> Two things:
> - Are you sure, this looks like of_syscon_register() is a static function
> - gcc node would be required to add "syscon" compatible
>
> Unless am missing some patches, Am not sure if going via syscon is
> right thing here?
>
> Stephen Any comments?

I don't understand any of this. We should be making a specific tsens
device directly in the gcc driver probe and not doing any sort of
of_platform_populate(). This is what I had, but it probably could be
done better so that we can assign the struct device's of_node pointer
before registering on the platform bus.

        platform_device_register_data(&pdev->dev, "tsens8960-tm", -1,
                        &pdev->dev.of_node, sizeof(&pdev->dev.of_node));

Then if we need to add any properties like #sensor-cells or coefficients
the tsens driver can use the same of_node that gcc is using.

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project

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