linux-kernel - Re: [v2,5/6] reset-controller: ti: Introduce force-update method

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Date:   Wed, 2 Sep 2020 18:05:12 -0500
From:   Suman Anna <s-anna@...com>
To:     Crystal Guo <crystal.guo@...iatek.com>,
        Philipp Zabel <p.zabel@...gutronix.de>
CC:     "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "matthias.bgg@...il.com" <matthias.bgg@...il.com>,
        srv_heupstream <srv_heupstream@...iatek.com>,
        "linux-mediatek@...ts.infradead.org" 
        <linux-mediatek@...ts.infradead.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Seiya Wang (王迺君) 
        <seiya.wang@...iatek.com>,
        Stanley Chu (朱原陞) 
        <stanley.chu@...iatek.com>,
        Yingjoe Chen (陳英洲) 
        <Yingjoe.Chen@...iatek.com>,
        Fan Chen (陳凡) <fan.chen@...iatek.com>,
        Yong Liang (梁勇) <Yong.Liang@...iatek.com>
Subject: Re: [v2,5/6] reset-controller: ti: Introduce force-update method

Hi Crystal,

On 8/10/20 1:57 AM, Crystal Guo wrote:
> On Tue, 2020-08-04 at 15:03 +0800, Philipp Zabel wrote:
>> Hi Crystal,
>>
>> On Mon, 2020-08-03 at 14:15 +0800, Crystal Guo wrote:
>>> Introduce force-update method for assert and deassert interface,
>>> which force the write operation in case the read already happens
>>> to return the correct value.
>>>
>>> Signed-off-by: Crystal Guo <crystal.guo@...iatek.com>
>>
>> Added Suman and Andrew for confirmation: I think writing unconditionally
>> can't break any existing user. Just changing to regmap_write_bits()
>> instead of adding the update-force property as in v1 should be fine.
>>
>> regards
>> Philipp
>>
> Hi Suman, Andrew,
> 
> Can you help to give some suggestions about this change.
> Is this can be changed to write unconditionally, or should I add a
> update-force property to force the write operation.

Sorry for the delay on this one, I have tested your latest v4, and everything is
functional on the TI SoCs. We do use the same register for asserting and
deasserting and is not self-clearing, and have additional non-reset related bits
in the register, so this change doesn't impact us. I have some minor
comments/questions that I will post on your v4.

Removing Andrew to not have the emails bounce.

regards
Suman

> 
> Best regards
> Crystal.
> 
>>> ---
>>>  drivers/reset/reset-ti-syscon.c | 15 +++++++++++++--
>>>  1 file changed, 13 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/reset/reset-ti-syscon.c b/drivers/reset/reset-ti-syscon.c
>>> index 1c74bcb9a6c3..f4baf78afd14 100644
>>> --- a/drivers/reset/reset-ti-syscon.c
>>> +++ b/drivers/reset/reset-ti-syscon.c
>>> @@ -57,6 +57,7 @@ struct ti_syscon_reset_data {
>>>  	struct ti_syscon_reset_control *controls;
>>>  	unsigned int nr_controls;
>>>  	bool assert_deassert_together;
>>> +	bool update_force;
>>>  };
>>>  
>>>  #define to_ti_syscon_reset_data(rcdev)	\
>>> @@ -90,7 +91,10 @@ 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);
>>> +	if (data->update_force)
>>> +		return regmap_write_bits(data->regmap, control->assert_offset, mask, value);
>>> +	else
>>> +		return regmap_update_bits(data->regmap, control->assert_offset, mask, value);
>>>  }
>>>  
>>>  /**
>>> @@ -121,7 +125,10 @@ 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);
>>> +	if (data->update_force)
>>> +		return regmap_write_bits(data->regmap, control->deassert_offset, mask, value);
>>> +	else
>>> +		return regmap_update_bits(data->regmap, control->deassert_offset, mask, value);
>>>  }
>>>  
>>>  /**
>>> @@ -223,6 +230,10 @@ static int ti_syscon_reset_probe(struct platform_device *pdev)
>>>  		data->assert_deassert_together = true;
>>>  	else
>>>  		data->assert_deassert_together = false;
>>> +	if (of_property_read_bool(np, "update-force"))
>>> +		data->update_force = true;
>>> +	else
>>> +		data->update_force = false;
>>>  
>>>  	data->rcdev.ops = &ti_syscon_reset_ops;
>>>  	data->rcdev.owner = THIS_MODULE;
>>> -- 
>>> 2.18.0
>