Date:	Wed, 20 Apr 2016 02:02:25 +0200
From:	Marek Vasut <marex@...x.de>
To:	netdev@...r.kernel.org
CC:	peppe.cavallaro@...com, alexandre.torgue@...com,
	Matthew Gerlach <mgerlach@...nsource.altera.com>,
	Dinh Nguyen <dinguyen@...nsource.altera.com>,
	"David S . Miller" <davem@...emloft.net>
Subject: Re: [PATCH] net: stmmac: socfpga: Remove re-registration of reset
 controller

On 04/20/2016 01:49 AM, Marek Vasut wrote:
> 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>
> ---
>  .../net/ethernet/stmicro/stmmac/dwmac-socfpga.c    | 69 ++++++++++++----------
>  1 file changed, 38 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..9ece2dd 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 +228,37 @@ 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;

There should be stmmac_rst = NULL; here, so the checks below work
correctly. Will be added in V2 if the idea of this patch makes sense.

> +	}
> +
> +	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 +287,9 @@ 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;
>  
> 


-- 
Best regards,
Marek Vasut

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