Date:	Wed, 20 Apr 2016 02:05:53 +0200
From:	Marek Vasut <marex@...x.de>
To:	netdev@...r.kernel.org
Cc:	peppe.cavallaro@...com, alexandre.torgue@...com,
	Marek Vasut <marex@...x.de>,
	Matthew Gerlach <mgerlach@...nsource.altera.com>,
	Dinh Nguyen <dinguyen@...nsource.altera.com>,
	"David S . Miller" <davem@...emloft.net>
Subject: [PATCH V2] net: stmmac: socfpga: Remove re-registration of reset controller

Both socfpga_dwmac_parse_data() in dwmac-socfpga.c and stmmac_dvr_probe()
in stmmac_main.c functions call devm_reset_control_get() to register an
reset controller for the stmmac. This results in an attempt to register
two reset controllers for the same non-shared reset line.

The first attempt to register the reset controller works fine. The second
attempt fails with warning from the reset controller core, see below.
The warning is produced because the reset line is non-shared and thus
it is allowed to have only up-to one reset controller associated with
that reset line, not two or more.

The solution is not great. Since the hardware needs to toggle the reset
before calling stmmac_dvr_probe() to perform mandatory preconfiguration,
this patch splits socfpga_dwmac_init_probe() from socfpga_dwmac_init().

The socfpga_dwmac_init_probe() temporarily registers the reset controller,
performs the pre-configuration and unregisters the reset controller again.
This function is only called from the socfpga_dwmac_probe().

The original socfpga_dwmac_init() is tweaked to use reset controller
pointer from the stmmac_priv (private data of the stmmac core) instead
of the local instance, which was used before.

Finally, plat_dat->exit and socfpga_dwmac_exit() is no longer necessary,
since the functionality is already performed by the stmmac core.

------------[ cut here ]------------
WARNING: CPU: 0 PID: 1 at drivers/reset/core.c:187 __of_reset_control_get+0x218/0x270
Modules linked in:
CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.6.0-rc4-next-20160419-00015-gabb2477-dirty #4
Hardware name: Altera SOCFPGA
[<c010f290>] (unwind_backtrace) from [<c010b82c>] (show_stack+0x10/0x14)
[<c010b82c>] (show_stack) from [<c0373da4>] (dump_stack+0x94/0xa8)
[<c0373da4>] (dump_stack) from [<c011bcc0>] (__warn+0xec/0x104)
[<c011bcc0>] (__warn) from [<c011bd88>] (warn_slowpath_null+0x20/0x28)
[<c011bd88>] (warn_slowpath_null) from [<c03a6eb4>] (__of_reset_control_get+0x218/0x270)
[<c03a6eb4>] (__of_reset_control_get) from [<c03a701c>] (__devm_reset_control_get+0x54/0x90)
[<c03a701c>] (__devm_reset_control_get) from [<c041fa30>] (stmmac_dvr_probe+0x1b4/0x8e8)
[<c041fa30>] (stmmac_dvr_probe) from [<c04298c8>] (socfpga_dwmac_probe+0x1b8/0x28c)
[<c04298c8>] (socfpga_dwmac_probe) from [<c03d6ffc>] (platform_drv_probe+0x4c/0xb0)
[<c03d6ffc>] (platform_drv_probe) from [<c03d54ec>] (driver_probe_device+0x224/0x2bc)
[<c03d54ec>] (driver_probe_device) from [<c03d5630>] (__driver_attach+0xac/0xb0)
[<c03d5630>] (__driver_attach) from [<c03d382c>] (bus_for_each_dev+0x6c/0xa0)
[<c03d382c>] (bus_for_each_dev) from [<c03d4ad4>] (bus_add_driver+0x1a4/0x21c)
[<c03d4ad4>] (bus_add_driver) from [<c03d60ac>] (driver_register+0x78/0xf8)
[<c03d60ac>] (driver_register) from [<c0101760>] (do_one_initcall+0x40/0x170)
[<c0101760>] (do_one_initcall) from [<c0800e38>] (kernel_init_freeable+0x1dc/0x27c)
[<c0800e38>] (kernel_init_freeable) from [<c05d1bd4>] (kernel_init+0x8/0x114)
[<c05d1bd4>] (kernel_init) from [<c01076f8>] (ret_from_fork+0x14/0x3c)
---[ end trace 059d2fbe87608fa9 ]---

Signed-off-by: Marek Vasut <marex@...x.de>
Cc: Matthew Gerlach <mgerlach@...nsource.altera.com>
Cc: Dinh Nguyen <dinguyen@...nsource.altera.com>
Cc: David S. Miller <davem@...emloft.net>
---
V2: Add missing stmmac_rst = NULL; into socfpga_dwmac_init_probe()
---
 .../net/ethernet/stmicro/stmmac/dwmac-socfpga.c    | 70 ++++++++++++----------
 1 file changed, 39 insertions(+), 31 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-socfpga.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-socfpga.c
index 76d671e..5885a2e 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac-socfpga.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-socfpga.c
@@ -49,7 +49,6 @@ struct socfpga_dwmac {
 	u32	reg_shift;
 	struct	device *dev;
 	struct regmap *sys_mgr_base_addr;
-	struct reset_control *stmmac_rst;
 	void __iomem *splitter_base;
 	bool f2h_ptp_ref_clk;
 };
@@ -92,15 +91,6 @@ static int socfpga_dwmac_parse_data(struct socfpga_dwmac *dwmac, struct device *
 	struct device_node *np_splitter;
 	struct resource res_splitter;
 
-	dwmac->stmmac_rst = devm_reset_control_get(dev,
-						  STMMAC_RESOURCE_NAME);
-	if (IS_ERR(dwmac->stmmac_rst)) {
-		dev_info(dev, "Could not get reset control!\n");
-		if (PTR_ERR(dwmac->stmmac_rst) == -EPROBE_DEFER)
-			return -EPROBE_DEFER;
-		dwmac->stmmac_rst = NULL;
-	}
-
 	dwmac->interface = of_get_phy_mode(np);
 
 	sys_mgr_base_addr = syscon_regmap_lookup_by_phandle(np, "altr,sysmgr-syscon");
@@ -194,30 +184,23 @@ static int socfpga_dwmac_setup(struct socfpga_dwmac *dwmac)
 	return 0;
 }
 
-static void socfpga_dwmac_exit(struct platform_device *pdev, void *priv)
-{
-	struct socfpga_dwmac	*dwmac = priv;
-
-	/* On socfpga platform exit, assert and hold reset to the
-	 * enet controller - the default state after a hard reset.
-	 */
-	if (dwmac->stmmac_rst)
-		reset_control_assert(dwmac->stmmac_rst);
-}
-
 static int socfpga_dwmac_init(struct platform_device *pdev, void *priv)
 {
-	struct socfpga_dwmac	*dwmac = priv;
+	struct socfpga_dwmac *dwmac = priv;
 	struct net_device *ndev = platform_get_drvdata(pdev);
 	struct stmmac_priv *stpriv = NULL;
 	int ret = 0;
 
-	if (ndev)
-		stpriv = netdev_priv(ndev);
+	if (!ndev)
+		return -EINVAL;
+
+	stpriv = netdev_priv(ndev);
+	if (!stpriv)
+		return -EINVAL;
 
 	/* Assert reset to the enet controller before changing the phy mode */
-	if (dwmac->stmmac_rst)
-		reset_control_assert(dwmac->stmmac_rst);
+	if (stpriv->stmmac_rst)
+		reset_control_assert(stpriv->stmmac_rst);
 
 	/* Setup the phy mode in the system manager registers according to
 	 * devicetree configuration
@@ -227,8 +210,8 @@ static int socfpga_dwmac_init(struct platform_device *pdev, void *priv)
 	/* Deassert reset for the phy configuration to be sampled by
 	 * the enet controller, and operation to start in requested mode
 	 */
-	if (dwmac->stmmac_rst)
-		reset_control_deassert(dwmac->stmmac_rst);
+	if (stpriv->stmmac_rst)
+		reset_control_deassert(stpriv->stmmac_rst);
 
 	/* Before the enet controller is suspended, the phy is suspended.
 	 * This causes the phy clock to be gated. The enet controller is
@@ -245,12 +228,38 @@ static int socfpga_dwmac_init(struct platform_device *pdev, void *priv)
 	 * control register 0, and can be modified by the phy driver
 	 * framework.
 	 */
-	if (stpriv && stpriv->phydev)
+	if (stpriv->phydev)
 		phy_resume(stpriv->phydev);
 
 	return ret;
 }
 
+static int socfpga_dwmac_init_probe(struct socfpga_dwmac *dwmac)
+{
+	struct reset_control *stmmac_rst;
+	int ret;
+
+	stmmac_rst = reset_control_get(dwmac->dev, STMMAC_RESOURCE_NAME);
+	if (IS_ERR(stmmac_rst)) {
+		dev_info(dwmac->dev, "Could not get reset control!\n");
+		if (PTR_ERR(stmmac_rst) == -EPROBE_DEFER)
+			return -EPROBE_DEFER;
+		stmmac_rst = NULL;
+	}
+
+	if (stmmac_rst)
+		reset_control_assert(stmmac_rst);
+
+	ret = socfpga_dwmac_setup(dwmac);
+
+	if (stmmac_rst) {
+		reset_control_deassert(stmmac_rst);
+		reset_control_put(stmmac_rst);
+	}
+
+	return ret;
+}
+
 static int socfpga_dwmac_probe(struct platform_device *pdev)
 {
 	struct plat_stmmacenet_data *plat_dat;
@@ -279,10 +288,9 @@ static int socfpga_dwmac_probe(struct platform_device *pdev)
 
 	plat_dat->bsp_priv = dwmac;
 	plat_dat->init = socfpga_dwmac_init;
-	plat_dat->exit = socfpga_dwmac_exit;
 	plat_dat->fix_mac_speed = socfpga_dwmac_fix_mac_speed;
 
-	ret = socfpga_dwmac_init(pdev, plat_dat->bsp_priv);
+	ret = socfpga_dwmac_init_probe(dwmac);
 	if (ret)
 		return ret;
 
-- 
2.7.0

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