linux-kernel - Re: [PATCH v3 1/3] phy: amlogic: phy-meson-gxl-usb2: fix shared reset controller use

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Message-ID: <76927781-c420-b6f6-78e9-c6e91dec6ef4@baylibre.com>
Date:   Sun, 5 Dec 2021 22:13:41 +0100
From:   Amjad Ouled-Ameur <aouledameur@...libre.com>
To:     Philipp Zabel <p.zabel@...gutronix.de>, khilman@...libre.com
Cc:     balbi@...nel.org, jbrunet@...libre.com,
        linux-amlogic@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-usb@...r.kernel.org
Subject: Re: [PATCH v3 1/3] phy: amlogic: phy-meson-gxl-usb2: fix shared reset
 controller use

Hi Philipp,

Thank you for the review.

On 22/11/2021 10:03, Philipp Zabel wrote:
> Hi Amjad,
>
> On Fri, 2021-11-12 at 17:28 +0100, Amjad Ouled-Ameur wrote:
>> Use reset_control_rearm() call if an error occurs in case
>> phy_meson_gxl_usb2_init() fails after reset() has been called ; or in case
>> phy_meson_gxl_usb2_exit() is called i.e the resource is no longer used
>> and the reset line may be triggered again by other devices.
>>
>> reset_control_rearm() keeps use of triggered_count sane in the reset
>> framework. Therefore, use of reset_control_reset() on shared reset line
>> should be balanced with reset_control_rearm().
>>
>> Signed-off-by: Amjad Ouled-Ameur <aouledameur@...libre.com>
>> Reported-by: Jerome Brunet <jbrunet@...libre.com>
>> ---
>>   drivers/phy/amlogic/phy-meson-gxl-usb2.c | 5 ++++-
>>   1 file changed, 4 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/phy/amlogic/phy-meson-gxl-usb2.c b/drivers/phy/amlogic/phy-meson-gxl-usb2.c
>> index 2b3c0d730f20..9a9c769ecabc 100644
>> --- a/drivers/phy/amlogic/phy-meson-gxl-usb2.c
>> +++ b/drivers/phy/amlogic/phy-meson-gxl-usb2.c
>> @@ -110,8 +110,10 @@ static int phy_meson_gxl_usb2_init(struct phy *phy)
>>   	int ret;
>>
>>   	ret = reset_control_reset(priv->reset);
>> -	if (ret)
>> +	if (ret) {
>> +		reset_control_rearm(priv->reset);
> I don't understand this. If reset_control_reset() returns an error for a
> shared reset, it should have either
> - returned before incrementing triggered_count, or
> - incremented triggered_count, got a failed reset op, decremented
>    triggered_count again
>
> In both cases there should be no need to rearm.
>
I have checked this out and I agree with you, will remove this in next 
version.

Thank you for spotting this.


Regards,

Amjad

> regards
> Philipp