Subject: Re: [PATCH v5] sh_eth: ensure pm_runtime cannot suspend the device during init

From: Laurent Pinchart <[email-masked]>
Date: Fri, 21 Mar 2014 14:00:51 +0100

Hi Ben,

Thank you for the patch.

On Friday 21 March 2014 12:09:14 Ben Dooks wrote:
> The pm_rumtime work queue is causing the device to be suspended during
> initialisation, thus the initialisation may not be able to access registers
> properly. As the code is called from a work queue, it is possible that this
> is not seen from certain configurations/builds due to the asynchronos
> nature of the code.
> 
> Another issue has also been found where the network device registration
> calls back into the driver thus causing further pm_runtime calls that
> also caused issues with the MDIO bus code. This has now been checked
> and is the only place the MDIO can be called without the device open.
> 
> Use pm_runtime_get_sync() and pm_runtime_put() to ensure that the
> pm system does not suspend it during the probe() call and remove the
> now unnecessary pm_runtime_resume() call. Also add a call in the error
> path to call pm_runtime_disable().
> 
> This fixes the external abort that can cause /sbin/init or other such
> init processed to die.
> 
> Signed-off-by: Ben Dooks <[email-masked]>
> Tested-by: Geert Uytterhoeven <[email-masked]>

Acked-by: Laurent Pinchart <[email-masked]>

> 
> ---
> Cc: [email-masked]
> Cc: [email-masked]
> cc: [email-masked]
> 
> Note, Laurent this should probably be applied before your
> current series as it may require changes to the exit sequence.
> 
> Fixes from v1:
> 	- use pm_runtime_put() over pm_runtime_put_sync() as
> 	  we do not need to guaranteed the device has powered
>           off after probe.
> 
> Fixed from v2:
> 	- call pm_runtime_put() in error path
> 
> Fixed from v3:
> 	- call pm_runtime_disable() in error path
> 
> Conflicts:
> 	drivers/net/ethernet/renesas/sh_eth.c
> ---
>  drivers/net/ethernet/renesas/sh_eth.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ethernet/renesas/sh_eth.c
> b/drivers/net/ethernet/renesas/sh_eth.c index e4bff18..6a9509c 100644
> --- a/drivers/net/ethernet/renesas/sh_eth.c
> +++ b/drivers/net/ethernet/renesas/sh_eth.c
> @@ -2772,6 +2772,9 @@ static int sh_eth_drv_probe(struct platform_device
> *pdev) if (!ndev)
>  		return -ENOMEM;
> 
> +	pm_runtime_enable(&pdev->dev);
> +	pm_runtime_get_sync(&pdev->dev);
> +
>  	/* The sh Ether-specific entries in the device structure. */
>  	ndev->base_addr = res->start;
>  	devno = pdev->id;
> @@ -2799,8 +2802,6 @@ static int sh_eth_drv_probe(struct platform_device
> *pdev)
> 
>  	spin_lock_init(&mdp->lock);
>  	mdp->pdev = pdev;
> -	pm_runtime_enable(&pdev->dev);
> -	pm_runtime_resume(&pdev->dev);
> 
>  	if (pdev->dev.of_node)
>  		pd = sh_eth_parse_dt(&pdev->dev);
> @@ -2898,6 +2899,7 @@ static int sh_eth_drv_probe(struct platform_device
> *pdev) netdev_info(ndev, "Base address at 0x%x, %pM, IRQ %d.\n",
>  		    (u32)ndev->base_addr, ndev->dev_addr, ndev->irq);
> 
> +	pm_runtime_put(&pdev->dev);
>  	platform_set_drvdata(pdev, ndev);
> 
>  	return ret;
> @@ -2911,6 +2913,8 @@ out_release:
>  	if (ndev)
>  		free_netdev(ndev);
> 
> +	pm_runtime_put(&pdev->dev);
> +	pm_runtime_disable(&pdev->dev);
>  	return ret;
>  }

-- 
Regards,

Laurent Pinchart