netdev - [PATCH v3] sh_eth: ensure pm_runtime cannot suspend the device during init

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Date:	Thu, 20 Mar 2014 18:34:37 +0100
From:	Ben Dooks <ben.dooks@...ethink.co.uk>
To:	linux-kernel@...ts.codethink.co.uk, netdev@...r.kernel.org
Cc:	linux-sh@...r.kernel.org, davem@...emloft.net,
	Ben Dooks <ben.dooks@...ethink.co.uk>,
	sergei.shtylyov@...entembedded.com,
	laurent.pinchart+renesas@...asonboard.com
Subject: [PATCH v3] sh_eth: ensure pm_runtime cannot suspend the device during init

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.

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.

This fixes the external abort that can cause /sbin/init or other such
init processed to die.

Signed-off-by: Ben Dooks <ben.dooks@...ethink.co.uk>
Tested-by: Geert Uytterhoeven <geert@...ux-m68k.org>

---
Cc: sergei.shtylyov@...entembedded.com
Cc: laurent.pinchart+renesas@...asonboard.com
cc: netdev@...r.kernel.org

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
---
 drivers/net/ethernet/renesas/sh_eth.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/renesas/sh_eth.c b/drivers/net/ethernet/renesas/sh_eth.c
index 4f76b5e..610da51 100644
--- a/drivers/net/ethernet/renesas/sh_eth.c
+++ b/drivers/net/ethernet/renesas/sh_eth.c
@@ -2841,6 +2841,9 @@ static int sh_eth_drv_probe(struct platform_device *pdev)
 		goto out;
 	}
 
+	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;
@@ -2868,8 +2871,6 @@ 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);
@@ -2961,6 +2962,7 @@ static int sh_eth_drv_probe(struct platform_device *pdev)
 	pr_info("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;
@@ -2976,6 +2978,7 @@ out_release:
 	if (ndev)
 		free_netdev(ndev);
 
+	pm_runtime_put(&pdev->dev);
 out:
 	return ret;
 }
-- 
1.9.0

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