netdev - Re: [PATCH net 1/3] lan78xx: PHY DSP registers initialization to address EEE link drop issues with long cables

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Date:   Fri, 6 Apr 2018 16:43:42 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     Raghuram Chary J <raghuramchary.jallipalli@...rochip.com>
Cc:     davem@...emloft.net, netdev@...r.kernel.org,
        unglinuxdriver@...rochip.com, woojung.huh@...rochip.com
Subject: Re: [PATCH net 1/3] lan78xx: PHY DSP registers initialization to
 address EEE link drop issues with long cables

On Fri, Apr 06, 2018 at 11:42:02AM +0530, Raghuram Chary J wrote:
> The patch is to configure DSP registers of PHY device
> to handle Gbe-EEE failures with >40m cable length.
> 
> Fixes: 55d7de9de6c3 ("Microchip's LAN7800 family USB 2/3 to 10/100/1000 Ethernet device driver")
> Signed-off-by: Raghuram Chary J <raghuramchary.jallipalli@...rochip.com>
> ---
>  drivers/net/phy/microchip.c  | 123 ++++++++++++++++++++++++++++++++++++++++++-
>  include/linux/microchipphy.h |   8 +++
>  2 files changed, 130 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/phy/microchip.c b/drivers/net/phy/microchip.c
> index 0f293ef28935..174ae9808722 100644
> --- a/drivers/net/phy/microchip.c
> +++ b/drivers/net/phy/microchip.c
> @@ -20,6 +20,7 @@
>  #include <linux/ethtool.h>
>  #include <linux/phy.h>
>  #include <linux/microchipphy.h>
> +#include <linux/delay.h>
>  
>  #define DRIVER_AUTHOR	"WOOJUNG HUH <woojung.huh@...rochip.com>"
>  #define DRIVER_DESC	"Microchip LAN88XX PHY driver"
> @@ -66,6 +67,107 @@ static int lan88xx_suspend(struct phy_device *phydev)
>  	return 0;
>  }
>  
> +static void lan88xx_TR_reg_set(struct phy_device *phydev, u16 regaddr,
> +			       u32 data)
> +{
> +	int val;
> +	u16 buf;
> +
> +	/* Get access to token ring page */
> +	phy_write(phydev, LAN88XX_EXT_PAGE_ACCESS,
> +		  LAN88XX_EXT_PAGE_ACCESS_TR);

Hi Raghuram

You might want to look at phy_read_paged(), phy_write_paged(), etc.

There can be race conditions with paged access.

      Andrew