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Date:   Sat, 23 Feb 2019 16:25:40 +0100
From:   Andrew Lunn <andrew@lunn.ch>
To:     Parshuram Thombare <pthombar@cadence.com>
Cc:     nicolas.ferre@microchip.com, davem@davemloft.net,
        netdev@vger.kernel.org, f.fainelli@gmail.com, hkallweit1@gmail.com,
        linux-kernel@vger.kernel.org, rafalc@cadence.com,
        piotrs@cadence.com, jank@cadence.com
Subject: Re: [PATCH 2/3] net: ethernet: add c45 PHY support in MDIO
 read/write functions.
Message-ID: <20190223152540.GE10693@lunn.ch>
References: <20190222201242.GA20889@lvlogina.cadence.com>
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On Fri, Feb 22, 2019 at 08:12:42PM +0000, Parshuram Thombare wrote:
> This patch modify MDIO read/write functions to support
> communication with C45 PHY in Cadence ethernet controller driver.
> 
> Signed-off-by: Parshuram Thombare <pthombar@cadence.com>
> ---
>  drivers/net/ethernet/cadence/macb.h      |   15 +++++--
>  drivers/net/ethernet/cadence/macb_main.c |   61 ++++++++++++++++++++++++-----
>  2 files changed, 61 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/net/ethernet/cadence/macb.h b/drivers/net/ethernet/cadence/macb.h
> index bed4ded..59c23e0 100644
> --- a/drivers/net/ethernet/cadence/macb.h
> +++ b/drivers/net/ethernet/cadence/macb.h
> @@ -636,10 +636,17 @@
>  #define GEM_CLK_DIV96				5
>  
>  /* Constants for MAN register */
> -#define MACB_MAN_SOF				1
> -#define MACB_MAN_WRITE				1
> -#define MACB_MAN_READ				2
> -#define MACB_MAN_CODE				2
> +#define MACB_MAN_C22_SOF                        1
> +#define MACB_MAN_C22_WRITE                      1
> +#define MACB_MAN_C22_READ                       2
> +#define MACB_MAN_C22_CODE                       2
> +
> +#define MACB_MAN_C45_SOF                        0
> +#define MACB_MAN_C45_ADDR                       0
> +#define MACB_MAN_C45_WRITE                      1
> +#define MACB_MAN_C45_POST_READ_INCR             2
> +#define MACB_MAN_C45_READ                       3
> +#define MACB_MAN_C45_CODE                       2
>  
>  /* Capability mask bits */
>  #define MACB_CAPS_ISR_CLEAR_ON_WRITE		0x00000001
> diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
> index 4f4f8e5..2494abf 100644
> --- a/drivers/net/ethernet/cadence/macb_main.c
> +++ b/drivers/net/ethernet/cadence/macb_main.c
> @@ -323,11 +323,30 @@ static int macb_mdio_read(struct mii_bus *bus, int mii_id, int regnum)
>  	struct macb *bp = bus->priv;
>  	int value;
>  
> -	macb_writel(bp, MAN, (MACB_BF(SOF, MACB_MAN_SOF)
> -			      | MACB_BF(RW, MACB_MAN_READ)
> -			      | MACB_BF(PHYA, mii_id)
> -			      | MACB_BF(REGA, regnum)
> -			      | MACB_BF(CODE, MACB_MAN_CODE)));
> +	if (regnum & MII_ADDR_C45) {
> +		macb_writel(bp, MAN, (MACB_BF(SOF, MACB_MAN_C45_SOF)
> +				| MACB_BF(RW, MACB_MAN_C45_ADDR)
> +				| MACB_BF(PHYA, mii_id)
> +				| MACB_BF(REGA, (regnum >> 16) & 0x1F)
> +				| MACB_BF(DATA, regnum & 0xFFFF)
> +				| MACB_BF(CODE, MACB_MAN_C45_CODE)));
> +
> +	/* wait for end of transfer */
> +	while (!MACB_BFEXT(IDLE, macb_readl(bp, NSR)))
> +		cpu_relax();

You need a timeout here, and anywhere you wait for the hardware to
complete. Try to make use of readx_poll_timeout() variants.

	  Andrew