netdev - Re: [net-next PATCH v3] drivers: net: cpsw: Add support to drive gpios for ethernet to be functional

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Message-ID: <20150908200618.GF4215@atomide.com>
Date:	Tue, 8 Sep 2015 13:06:18 -0700
From:	Tony Lindgren <tony@...mide.com>
To:	Mugunthan V N <mugunthanvnm@...com>
Cc:	netdev@...r.kernel.org, "David S . Miller" <davem@...emloft.net>,
	Sekhar Nori <nsekhar@...com>, linux-omap@...r.kernel.org,
	devicetree@...r.kernel.org
Subject: Re: [net-next PATCH v3] drivers: net: cpsw: Add support to drive
 gpios for ethernet to be functional

* Mugunthan V N <mugunthanvnm@...com> [150907 02:50]:
> In DRA72x EVM, by default slave 1 is connected to the onboard
> phy, but slave 2 pins are also muxed with video input module
> which is controlled by pcf857x gpio and currently to select slave
> 0 to connect to phy gpio hogging is used, but with
> omap2plus_defconfig the pcf857x gpio is built as module. So when
> using NFS on DRA72x EVM, board doesn't boot as gpio hogging do
> not set proper gpio state to connect slave 0 to phy as it is
> built as module and you do not see any errors for not setting
> gpio and just mentions dhcp reply not got.
> 
> To solve this issue, introducing "mode-gpios" in DT when gpio
> based muxing is required. This will throw a warning when gpio
> get fails and returns probe defer. When gpio-pcf857x module is
> installed, cpsw probes again and ethernet becomes functional.
> Verified this on DRA72x with pcf as module and ramdisk.
> 
> Signed-off-by: Mugunthan V N <mugunthanvnm@...com>

Acked-by: Tony Lindgren <tony@...mide.com>

> ---
> 
> Changes from v2:
> * Used mode-gpios, so that the driver is generic enough to handle
>   multiple gpios
> 
> This patch is tested on DRA72x, Logs [1] and pushed a branch [2]
> 
> [1]: http://pastebin.ubuntu.com/12306224/
> [2]: git://git.ti.com/~mugunthanvnm/ti-linux-kernel/linux.git cpsw-gpio-optional-v3
> 
> ---
>  Documentation/devicetree/bindings/net/cpsw.txt | 7 +++++++
>  drivers/net/ethernet/ti/cpsw.c                 | 9 +++++++++
>  2 files changed, 16 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/net/cpsw.txt b/Documentation/devicetree/bindings/net/cpsw.txt
> index a9df21a..676ecf6 100644
> --- a/Documentation/devicetree/bindings/net/cpsw.txt
> +++ b/Documentation/devicetree/bindings/net/cpsw.txt
> @@ -30,6 +30,13 @@ Optional properties:
>  - dual_emac		: Specifies Switch to act as Dual EMAC
>  - syscon		: Phandle to the system control device node, which is
>  			  the control module device of the am33x
> +- mode-gpios		: Should be added if one/multiple gpio lines are
> +			  required to be driven so that cpsw data lines
> +			  can be connected to the phy via selective mux.
> +			  For example in dra72x-evm, pcf gpio has to be
> +			  driven low so that cpsw slave 0 and phy data
> +			  lines are connected via mux.
> +
>  
>  Slave Properties:
>  Required properties:
> diff --git a/drivers/net/ethernet/ti/cpsw.c b/drivers/net/ethernet/ti/cpsw.c
> index 8fc90f1..c670317 100644
> --- a/drivers/net/ethernet/ti/cpsw.c
> +++ b/drivers/net/ethernet/ti/cpsw.c
> @@ -29,6 +29,7 @@
>  #include <linux/workqueue.h>
>  #include <linux/delay.h>
>  #include <linux/pm_runtime.h>
> +#include <linux/gpio.h>
>  #include <linux/of.h>
>  #include <linux/of_net.h>
>  #include <linux/of_device.h>
> @@ -2207,6 +2208,7 @@ static int cpsw_probe(struct platform_device *pdev)
>  	void __iomem			*ss_regs;
>  	struct resource			*res, *ss_res;
>  	const struct of_device_id	*of_id;
> +	struct gpio_descs		*mode;
>  	u32 slave_offset, sliver_offset, slave_size;
>  	int ret = 0, i;
>  	int irq;
> @@ -2232,6 +2234,13 @@ static int cpsw_probe(struct platform_device *pdev)
>  		goto clean_ndev_ret;
>  	}
>  
> +	mode = devm_gpiod_get_array_optional(&pdev->dev, "mode", GPIOD_OUT_LOW);
> +	if (IS_ERR(mode)) {
> +		ret = PTR_ERR(mode);
> +		dev_err(&pdev->dev, "gpio request failed, ret %d\n", ret);
> +		goto clean_ndev_ret;
> +	}
> +
>  	/*
>  	 * This may be required here for child devices.
>  	 */
> -- 
> 2.6.0.rc0.24.gec371ff
> 
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