linux-kernel - Re: [PATCH v2 1/2] ata: ahci_brcm: Perform reset after obtaining resources

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Message-ID: <0ff51b3e4443a03f1d3ee8d3091863e03a22c2cf.camel@pengutronix.de>
Date:   Tue, 07 Jan 2020 09:19:33 +0100
From:   Philipp Zabel <p.zabel@...gutronix.de>
To:     Florian Fainelli <f.fainelli@...il.com>,
        linux-kernel@...r.kernel.org
Cc:     bcm-kernel-feedback-list@...adcom.com,
        Jens Axboe <axboe@...nel.dk>, Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Hans de Goede <hdegoede@...hat.com>,
        Tejun Heo <tj@...nel.org>, Jaedon Shin <jaedon.shin@...il.com>,
        "open list:LIBATA SUBSYSTEM (Serial and Parallel ATA drivers)" 
        <linux-ide@...r.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>
Subject: Re: [PATCH v2 1/2] ata: ahci_brcm: Perform reset after obtaining
 resources

Hi Florian,

On Mon, 2020-01-06 at 11:19 -0800, Florian Fainelli wrote:
> Resources such as clocks, PHYs, regulators are likely to get a probe
> deferral return code, which could lead to the AHCI controller being
> reset a few times until it gets successfully probed. Since this is
> typically the most time consuming operation, move it after the resources
> have been acquired.
> 
> Signed-off-by: Florian Fainelli <f.fainelli@...il.com>
> ---
>  drivers/ata/ahci_brcm.c | 14 ++++++--------
>  1 file changed, 6 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/ata/ahci_brcm.c b/drivers/ata/ahci_brcm.c
> index 13ceca687104..70e3e386d52e 100644
> --- a/drivers/ata/ahci_brcm.c
> +++ b/drivers/ata/ahci_brcm.c
> @@ -453,15 +453,9 @@ static int brcm_ahci_probe(struct platform_device *pdev)
>  	else
>  		reset_name = "ahci";
>  
> -	priv->rcdev = devm_reset_control_get(&pdev->dev, reset_name);
> -	if (!IS_ERR_OR_NULL(priv->rcdev))
> -		reset_control_deassert(priv->rcdev);
> -
>  	hpriv = ahci_platform_get_resources(pdev, 0);
> -	if (IS_ERR(hpriv)) {
> -		ret = PTR_ERR(hpriv);
> -		goto out_reset;
> -	}
> +	if (IS_ERR(hpriv))
> +		return PTR_ERR(hpriv);
>  
>  	hpriv->plat_data = priv;
>  	hpriv->flags = AHCI_HFLAG_WAKE_BEFORE_STOP | AHCI_HFLAG_NO_WRITE_TO_RO;
> @@ -478,6 +472,10 @@ static int brcm_ahci_probe(struct platform_device *pdev)
>  		break;
>  	}
>  
> +	priv->rcdev = devm_reset_control_get(&pdev->dev, reset_name);
> +	if (!IS_ERR_OR_NULL(priv->rcdev))
> +		reset_control_deassert(priv->rcdev);
> +

Please use devm_reset_control_get_optional_exclusive(), that returns
NULL if the requested reset is not specified in the device tree. Do
return the error code on IS_ERR(). You can then call
reset_control_deassert() unconditionally, it checks for and ignores
the NULL pointer.

regards
Philipp