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From: Ikjoon Jang <ikjn@chromium.org>
To: Crystal Guo <crystal.guo@mediatek.com>
Cc: p.zabel@pengutronix.de, robh+dt@kernel.org,
	matthias.bgg@gmail.com, devicetree@vger.kernel.org,
	yong.liang@mediatek.com, stanley.chu@mediatek.com,
	srv_heupstream@mediatek.com, seiya.wang@mediatek.com,
	linux-kernel@vger.kernel.org, fan.chen@mediatek.com,
	linux-mediatek@lists.infradead.org, yingjoe.chen@mediatek.com,
	s-anna@ti.com, linux-arm-kernel@lists.infradead.org
Subject: Re: [v6, 3/3] reset-controller: ti: force the write operation when assert or deassert
Date: Mon, 30 Nov 2020 19:13:40 +0800	[thread overview]
Message-ID: <20201130111340.GA3042402@chromium.org> (raw)
In-Reply-To: <20200930022159.5559-4-crystal.guo@mediatek.com>

On Wed, Sep 30, 2020 at 10:21:59AM +0800, Crystal Guo wrote:
> Force the write operation in case the read already happens
> to return the correct value.
> 
> Signed-off-by: Crystal Guo <crystal.guo@mediatek.com>
> ---
>  drivers/reset/reset-ti-syscon.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/reset/reset-ti-syscon.c b/drivers/reset/reset-ti-syscon.c
> index 5d1f8306cd4f..c34394f1e9e2 100644
> --- a/drivers/reset/reset-ti-syscon.c
> +++ b/drivers/reset/reset-ti-syscon.c
> @@ -97,7 +97,7 @@ 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);
>  }

I don't think there are no reset controllers with cached regmap,
thus I don't think this is needed.
Are there any specific reasons behind this, what I've missed here?

We need to be sure that all other devices using this driver
should have no side effects on write.

I can think of a weird controller doing unwanted things internally
on every write disregarding the current state. (or is this overly
paranoid?)

>  
>  /**
> @@ -128,7 +128,7 @@ 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);
>  }
>  
>  /**

  reply	other threads:[~2020-11-30 11:14 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-30  2:21 [v6,0/3] introduce TI reset controller for MT8192 SoC Crystal Guo
2020-09-30  2:21 ` [v6,1/3] dt-binding: reset-controller: mediatek: add YAML schemas Crystal Guo
2020-10-14 13:30   ` Crystal Guo
2020-11-11  8:28     ` Stanley Chu
2020-12-03  7:41   ` Philipp Zabel
2020-12-26  9:06     ` Crystal Guo
2020-09-30  2:21 ` [v6,2/3] reset-controller: ti: introduce a new reset handler Crystal Guo
2020-11-30 10:35   ` Ikjoon Jang
2020-12-04  2:34     ` Crystal Guo
2020-09-30  2:21 ` [v6,3/3] reset-controller: ti: force the write operation when assert or deassert Crystal Guo
2020-11-30 11:13   ` Ikjoon Jang [this message]
2020-12-02 11:06     ` [v6, 3/3] " Crystal Guo
2020-12-03  3:30       ` Ikjoon Jang
2020-12-03  7:45   ` [v6,3/3] " Philipp Zabel

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