linux-kernel - RE: [PATCH] reset: rzg2l-usbphy-ctrl: Correct reset status check

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Message-ID:
 <TY3PR01MB11346BEF0C5C45C9EC6B3D3B586C82@TY3PR01MB11346.jpnprd01.prod.outlook.com>
Date: Tue, 4 Mar 2025 06:43:00 +0000
From: Biju Das <biju.das.jz@...renesas.com>
To: Prabhakar <prabhakar.csengg@...il.com>, Philipp Zabel
	<p.zabel@...gutronix.de>
CC: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-renesas-soc@...r.kernel.org" <linux-renesas-soc@...r.kernel.org>,
	Fabrizio Castro <fabrizio.castro.jz@...esas.com>, Prabhakar Mahadev Lad
	<prabhakar.mahadev-lad.rj@...renesas.com>, "stable@...r.kernel.org"
	<stable@...r.kernel.org>
Subject: RE: [PATCH] reset: rzg2l-usbphy-ctrl: Correct reset status check

Hi Prabhakar,

Thanks for the patch.

> -----Original Message-----
> From: Prabhakar <prabhakar.csengg@...il.com>
> Sent: 03 March 2025 19:09
> Subject: [PATCH] reset: rzg2l-usbphy-ctrl: Correct reset status check
> 
> From: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> 
> Ensure the reset status check explicitly evaluates whether all bits in `port_mask` are set. Replace
> the double negation (`!!`) with an equality check to prevent incorrect interpretation of partial bit
> matches as an asserted reset.
> 
> Fixes: bee08559701f ("reset: renesas: Add RZ/G2L usbphy control driver")
> Cc: stable@...r.kernel.org
> Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> ---
>  drivers/reset/reset-rzg2l-usbphy-ctrl.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/reset/reset-rzg2l-usbphy-ctrl.c b/drivers/reset/reset-rzg2l-usbphy-ctrl.c
> index 8a7f167e405e..6451f621e862 100644
> --- a/drivers/reset/reset-rzg2l-usbphy-ctrl.c
> +++ b/drivers/reset/reset-rzg2l-usbphy-ctrl.c
> @@ -88,7 +88,7 @@ static int rzg2l_usbphy_ctrl_status(struct reset_controller_dev *rcdev,
> 
>  	port_mask = id ? PHY_RESET_PORT2 : PHY_RESET_PORT1;
> 
> -	return !!(readl(priv->base + RESET) & port_mask);
> +	return (readl(priv->base + RESET) & port_mask) == port_mask;


As per the hardware manual, these status bit is valid only when
Only when sel_pxreset=1.

If sel_pxreset=0, we are reporting invalid status to the caller.

Maybe we should check sel_pxreset while setting it and read it back to
Ensure that it is set to 1 and in this function just check for
phyrst_x bit for reporting status

Cheers,
Biju

>  }
> 
>  static const struct of_device_id rzg2l_usbphy_ctrl_match_table[] = {
> --
> 2.43.0