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Subject: Re: [v4,3/4] reset-controller: ti: introduce a new reset handler
To:     Crystal Guo <crystal.guo@mediatek.com>,
        "p.zabel@pengutronix.de" <p.zabel@pengutronix.de>,
        "robh+dt@kernel.org" <robh+dt@kernel.org>,
        "matthias.bgg@gmail.com" <matthias.bgg@gmail.com>
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        <linux-mediatek@lists.infradead.org>,
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        <linux-arm-kernel@lists.infradead.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
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References: <20200817030324.5690-1-crystal.guo@mediatek.com>
 <20200817030324.5690-4-crystal.guo@mediatek.com>
 <3a5decee-5f31-e27d-a120-1f835241a87c@ti.com>
 <1599620279.14806.18.camel@mhfsdcap03>
 <096362e9-dee8-4e7a-2518-47328068c2fd@ti.com>
 <1599792140.14806.22.camel@mhfsdcap03>
From:   Suman Anna <s-anna@ti.com>
Message-ID: <9d72aaef-49fe-ebb6-215d-05ad3ab27af4@ti.com>
Date:   Thu, 10 Sep 2020 21:52:04 -0500
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On 9/10/20 9:42 PM, Crystal Guo wrote:
> On Wed, 2020-09-09 at 23:39 +0800, Suman Anna wrote:
>> On 9/8/20 9:57 PM, Crystal Guo wrote:
>>> On Thu, 2020-09-03 at 07:40 +0800, Suman Anna wrote:
>>>> Hi Crystal,
>>>>
>>>> On 8/16/20 10:03 PM, Crystal Guo wrote:
>>>>> Introduce ti_syscon_reset() to integrate assert and deassert together.
>>>>> If some modules need do serialized assert and deassert operations
>>>>> to reset itself, reset_control_reset can be called for convenience.
>>>>
>>>> There are multiple changes in this same patch. I think you should split this
>>>> functionality away from the change for the regmap_update_bits() to
>>>> regmap_write_bits(), similar to what you have done in your v2 Patch 4.
>>>>
>>>
>>> Thanks for your suggestion.
>>> I will split this patch in the next version.
>>>
>>>>>
>>>>> Such as reset-qcom-aoss.c, it integrates assert and deassert together
>>>>> by 'reset' method. MTK Socs also need this method to perform reset.
>>>>>
>>>>> Signed-off-by: Crystal Guo <crystal.guo@mediatek.com>
>>>>> ---
>>>>>  drivers/reset/reset-ti-syscon.c | 26 ++++++++++++++++++++++++--
>>>>>  1 file changed, 24 insertions(+), 2 deletions(-)
>>>>>
>>>>> diff --git a/drivers/reset/reset-ti-syscon.c b/drivers/reset/reset-ti-syscon.c
>>>>> index a2635c21db7f..08289342f9af 100644
>>>>> --- a/drivers/reset/reset-ti-syscon.c
>>>>> +++ b/drivers/reset/reset-ti-syscon.c
>>>>> @@ -15,6 +15,7 @@
>>>>>   * GNU General Public License for more details.
>>>>>   */
>>>>>  
>>>>> +#include <linux/delay.h>
>>>>>  #include <linux/mfd/syscon.h>
>>>>>  #include <linux/module.h>
>>>>>  #include <linux/of.h>
>>>>> @@ -56,6 +57,7 @@ struct ti_syscon_reset_data {
>>>>>  	struct regmap *regmap;
>>>>>  	struct ti_syscon_reset_control *controls;
>>>>>  	unsigned int nr_controls;
>>>>> +	unsigned int reset_duration_us;
>>>>>  };
>>>>>  
>>>>>  #define to_ti_syscon_reset_data(rcdev)	\
>>>>> @@ -89,7 +91,7 @@ static int ti_syscon_reset_assert(struct reset_controller_dev *rcdev,
>>>>>  	mask = BIT(control->assert_bit);
>>>>>  	value = (control->flags & ASSERT_SET) ? mask : 0x0;
>>>>>  
>>>>> -	return regmap_update_bits(data->regmap, control->assert_offset, mask, value);
>>>>> +	return regmap_write_bits(data->regmap, control->assert_offset, mask, value);
>>>>>  }
>>>>>  
>>>>>  /**
>>>>> @@ -120,7 +122,7 @@ static int ti_syscon_reset_deassert(struct reset_controller_dev *rcdev,
>>>>>  	mask = BIT(control->deassert_bit);
>>>>>  	value = (control->flags & DEASSERT_SET) ? mask : 0x0;
>>>>>  
>>>>> -	return regmap_update_bits(data->regmap, control->deassert_offset, mask, value);
>>>>> +	return regmap_write_bits(data->regmap, control->deassert_offset, mask, value);
>>>>>  }
>>>>>  
>>>>>  /**
>>>>> @@ -158,9 +160,26 @@ static int ti_syscon_reset_status(struct reset_controller_dev *rcdev,
>>>>>  		!(control->flags & STATUS_SET);
>>>>>  }
>>>>>  
>>>>> +static int ti_syscon_reset(struct reset_controller_dev *rcdev,
>>>>> +				  unsigned long id)
>>>>> +{
>>>>> +	struct ti_syscon_reset_data *data = to_ti_syscon_reset_data(rcdev);
>>>>> +	int ret;
>>>>> +
>>>>> +	ret = ti_syscon_reset_assert(rcdev, id);
>>>>> +	if (ret)
>>>>> +		return ret;
>>>>> +
>>>>> +	if (data->reset_duration_us)
>>>>> +		usleep_range(data->reset_duration_us, data->reset_duration_us * 2);
>>>>> +
>>>>> +	return ti_syscon_reset_deassert(rcdev, id);
>>>>
>>>> I echo Philipp's comments [1] from your original v1 series about this. We don't
>>>> need a property to distinguish this, but you could add a flag using match data
>>>> and Mediatek compatible, and use that within this function, or optionally set
>>>> this ops based on compatible (whatever is preferred by Philipp).
>>>>
>>>> regards
>>>> Suman
>>>>
>>>> [1] https://patchwork.kernel.org/comment/23519193/
>>>>
>>> Hi Suman, Philipp
>>>
>>> Which method would you recommend more?
>>> 1. like v2 patch, but assign the flag "data->assert_deassert_together"
>>> directly (maybe rename "assert_deassert_together" to
>>> "reset_op_available")
>>>
>>> 2. use Mediatek compatible to decide the reset handler available or not.
>>
>> I would go with this option. Anyway, I think you might have to add the reset SoC
>> data as well, based on Rob's comment on the binding.
>>
>> regards
>> Suman
> 
> 
> Thanks for your suggestions
> I will add the following changes in the next version, 
> please correct me if there is any misunderstanding.
> 1). revert ti-syscon-reset.txt add a new mediatek reset binding doc.
> 2). split the patch [v4,3/4] with the change for the
> regmap_update_bits() to regmap_write_bits() and the change to integrate
> assert and deassert together.
> 3). add the reset SoC data, which contains the flag "reset_op_available"
> to decide the reset handler available or not.

You would also need to add your SoC-specific data equivalent of the current
ti,reset-bits in your infra node. Please see Rob's comments on patch 2. Also,
your new Mediatek binding should be in YAML format.

regards
Suman

> 4). separate the dts patch from this patch sets
> 
>>>
>>> Thanks
>>> Crystal
>>>
>>>>> +}
>>>>> +
>>>>>  static const struct reset_control_ops ti_syscon_reset_ops = {
>>>>>  	.assert		= ti_syscon_reset_assert,
>>>>>  	.deassert	= ti_syscon_reset_deassert,
>>>>> +	.reset		= ti_syscon_reset,
>>>>>  	.status		= ti_syscon_reset_status,
>>>>>  };
>>>>>  
>>>>> @@ -204,6 +223,9 @@ static int ti_syscon_reset_probe(struct platform_device *pdev)
>>>>>  		controls[i].flags = be32_to_cpup(list++);
>>>>>  	}
>>>>>  
>>>>> +	of_property_read_u32(pdev->dev.of_node,	"reset-duration-us",
>>>>> +				&data->reset_duration_us);
>>>>> +
>>>>>  	data->rcdev.ops = &ti_syscon_reset_ops;
>>>>>  	data->rcdev.owner = THIS_MODULE;
>>>>>  	data->rcdev.of_node = np;
>>>>>
>>>>
>>>
>>
>