netdev - Re: [PATCH net-next v3 1/3] sh_eth: add support for gpio reset

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Date:	Thu, 04 Jul 2013 17:20:23 +0200
From:	Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:	Simon Horman <horms@...ge.net.au>
Cc:	Sergei Shtylyov <sergei.shtylyov@...entembedded.com>,
	netdev@...r.kernel.org, linux-sh@...r.kernel.org,
	Magnus Damm <magnus.damm@...il.com>
Subject: Re: [PATCH net-next v3 1/3] sh_eth: add support for gpio reset

Hi Simon,

On Tuesday 02 July 2013 14:25:00 Simon Horman wrote:
> On Mon, Jul 01, 2013 at 06:24:34PM +0400, Sergei Shtylyov wrote:
> > On 01-07-2013 8:24, Simon Horman wrote:
> > >Allow reset using a GPIO. In order to use this set the following
> > >
> > >in the device's platform data:
> > >	needs_gpio_reset = 1
> > >	reset_gpio = GPIO pin to use
> > >
> > >This patch is motivated by the lager board which uses the r8a7790 SoC
> > >which has a GPIO pin to reset its sh_eth device.
> > >
> > >Signed-off-by: Simon Horman <horms+renesas@...ge.net.au>
> > >
> > >--
> > >
> > >v2
> > >* First post
> > >---
> > >
> > >  drivers/net/ethernet/renesas/sh_eth.c | 4 ++++
> > >  include/linux/sh_eth.h                | 3 +++
> > >  2 files changed, 7 insertions(+)
> > >
> > >diff --git a/drivers/net/ethernet/renesas/sh_eth.c
> > >b/drivers/net/ethernet/renesas/sh_eth.c index 7732f11..0253f61 100644
> > >--- a/drivers/net/ethernet/renesas/sh_eth.c
> > >+++ b/drivers/net/ethernet/renesas/sh_eth.c
> > 
> > [...]
> > 
> > >@@ -2652,6 +2653,9 @@ static int sh_eth_drv_probe(struct platform_device
> > >*pdev)> >
> > >  		ndev->features = NETIF_F_HW_VLAN_CTAG_FILTER;
> > >  	
> > >  	}
> > >
> > >+	if (pd->needs_gpio_reset)
> > >+		gpio_request_one(pd->reset_gpio, GPIOF_OUT_INIT_HIGH, NULL);
> > >
> >    Is reset signal active low or active high? Are you asserting or
> > 
> > releasing it?
> 
> Good point.
> 
> I'm not sure that the documentation that I have is sufficient to answer
> that. Empirically it seems that this change isn't strictly necessary, so
> perhaps it would be best to drop it for now.

GPIO 5-31 is connected to the active-low reset input of the KSZ8041 PHY. 
Wouldn't it make more sense to handle it in the PHY framework ? More work is 
then be needed. If the Lager boot loader configures the GPIO correctly I would 
thus drop this patch.

-- 
Regards,

Laurent Pinchart

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