netdev - Re: [PATCH RfC 1/2] net: phy: core: remove now uneeded disabling of interrupts

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Date:   Wed, 15 Nov 2017 14:04:05 -0800
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Heiner Kallweit <hkallweit1@...il.com>,
        Andrew Lunn <andrew@...n.ch>,
        David Miller <davem@...emloft.net>
Cc:     netdev@...r.kernel.org, Ard Biesheuvel <ard.biesheuvel@...aro.org>
Subject: Re: [PATCH RfC 1/2] net: phy: core: remove now uneeded disabling of
 interrupts

On 11/12/2017 01:08 PM, Heiner Kallweit wrote:
> After commits c974bdbc3e "net: phy: Use threaded IRQ, to allow IRQ from
> sleeping devices" and 664fcf123a30 "net: phy: Threaded interrupts allow
> some simplification" all relevant code pieces run in process context
> anyway and I don't think we need the disabling of interrupts any longer.
> 
> Interestingly enough, latter commit already removed the comment
> explaining why interrupts need to be temporarily disabled.
> 
> On my system phy interrupt mode works fine with this patch.
> However I may miss something, especially in the context of shared phy
> interrupts, therefore I'd appreciate if more people could test this.

I am not currently in a position to test this, but this looks very
similar, if not identical to what Ard submitted a few days earlier:

https://patchwork.kernel.org/patch/10048901/

Since net-next is closed at the moment, that should allow us to give
this some good amount of testing.

Thanks

> 
> Signed-off-by: Heiner Kallweit <hkallweit1@...il.com>
> ---
>  drivers/net/phy/phy.c | 26 ++------------------------
>  include/linux/phy.h   |  1 -
>  2 files changed, 2 insertions(+), 25 deletions(-)
> 
> diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c
> index 2b1e67bc1..b3784c9a2 100644
> --- a/drivers/net/phy/phy.c
> +++ b/drivers/net/phy/phy.c
> @@ -629,9 +629,6 @@ static irqreturn_t phy_interrupt(int irq, void *phy_dat)
>  	if (PHY_HALTED == phydev->state)
>  		return IRQ_NONE;		/* It can't be ours.  */
>  
> -	disable_irq_nosync(irq);
> -	atomic_inc(&phydev->irq_disable);
> -
>  	phy_change(phydev);
>  
>  	return IRQ_HANDLED;
> @@ -689,7 +686,6 @@ static int phy_disable_interrupts(struct phy_device *phydev)
>   */
>  int phy_start_interrupts(struct phy_device *phydev)
>  {
> -	atomic_set(&phydev->irq_disable, 0);
>  	if (request_threaded_irq(phydev->irq, NULL, phy_interrupt,
>  				 IRQF_ONESHOT | IRQF_SHARED,
>  				 phydev_name(phydev), phydev) < 0) {
> @@ -716,13 +712,6 @@ int phy_stop_interrupts(struct phy_device *phydev)
>  
>  	free_irq(phydev->irq, phydev);
>  
> -	/* If work indeed has been cancelled, disable_irq() will have
> -	 * been left unbalanced from phy_interrupt() and enable_irq()
> -	 * has to be called so that other devices on the line work.
> -	 */
> -	while (atomic_dec_return(&phydev->irq_disable) >= 0)
> -		enable_irq(phydev->irq);
> -
>  	return err;
>  }
>  EXPORT_SYMBOL(phy_stop_interrupts);
> @@ -736,7 +725,7 @@ void phy_change(struct phy_device *phydev)
>  	if (phy_interrupt_is_valid(phydev)) {
>  		if (phydev->drv->did_interrupt &&
>  		    !phydev->drv->did_interrupt(phydev))
> -			goto ignore;
> +			return;
>  
>  		if (phy_disable_interrupts(phydev))
>  			goto phy_err;
> @@ -748,27 +737,16 @@ void phy_change(struct phy_device *phydev)
>  	mutex_unlock(&phydev->lock);
>  
>  	if (phy_interrupt_is_valid(phydev)) {
> -		atomic_dec(&phydev->irq_disable);
> -		enable_irq(phydev->irq);
> -
>  		/* Reenable interrupts */
>  		if (PHY_HALTED != phydev->state &&
>  		    phy_config_interrupt(phydev, PHY_INTERRUPT_ENABLED))
> -			goto irq_enable_err;
> +			goto phy_err;
>  	}
>  
>  	/* reschedule state queue work to run as soon as possible */
>  	phy_trigger_machine(phydev, true);
>  	return;
>  
> -ignore:
> -	atomic_dec(&phydev->irq_disable);
> -	enable_irq(phydev->irq);
> -	return;
> -
> -irq_enable_err:
> -	disable_irq(phydev->irq);
> -	atomic_inc(&phydev->irq_disable);
>  phy_err:
>  	phy_error(phydev);
>  }
> diff --git a/include/linux/phy.h b/include/linux/phy.h
> index dc82a07cb..8a87e441f 100644
> --- a/include/linux/phy.h
> +++ b/include/linux/phy.h
> @@ -468,7 +468,6 @@ struct phy_device {
>  	/* Interrupt and Polling infrastructure */
>  	struct work_struct phy_queue;
>  	struct delayed_work state_queue;
> -	atomic_t irq_disable;
>  
>  	struct mutex lock;
>  
> 


-- 
Florian