linux-kernel - Re: [EXTERNAL] Re: [RESEND PATCH] net: ethernet: ti: davinci

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Date:   Tue, 9 Aug 2022 17:00:20 +0530
From:   Ravi Gunasekaran <r-gunasekaran@...com>
To:     Andrew Lunn <andrew@...n.ch>
CC:     <davem@...emloft.net>, <edumazet@...gle.com>, <kuba@...nel.org>,
        <pabeni@...hat.com>, <linux-omap@...r.kernel.org>,
        <netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>, <kishon@...com>,
        <vigneshr@...com>
Subject: Re: [EXTERNAL] Re: [RESEND PATCH] net: ethernet: ti: davinci_mdio:
 Add workaround for errata i2329

Hello Andrew,

On 09/08/22 1:43 am, Andrew Lunn wrote:
>> +static int davinci_mdio_sw_read(struct mii_bus *bus, int phy_id, int phy_reg)
>> +{
>> +	struct davinci_mdio_data *data = bus->priv;
>> +	u32 reg, i;
>> +	int ret;
>> +	u8 ack;
>> +
>> +	if (phy_reg & ~PHY_REG_MASK || phy_id & ~PHY_ID_MASK)
>> +		return -EINVAL;
>> +
>> +	ret = pm_runtime_get_sync(data->dev);
>> +	if (ret < 0) {
>> +		pm_runtime_put_noidle(data->dev);
>> +		return ret;
>> +	}
>> +
>> +	davinci_mdio_disable(data);
>> +	davinci_mdio_enable_manual_mode(data);
>> +	davinci_mdio_sw_preamble(data);
>> +
>> +	davinci_mdio_sw_clr_bit(data, MDIO_MDCLK);
>> +	davinci_mdio_sw_set_bit(data, MDIO_OE);
>> +
>> +	 /* Issue clause 22 MII read function {0,1,1,0} */
>> +	davinci_mdio_man_send_pattern(data, C22_BITRANGE, C22_READ_PATTERN);
>> +
>> +	/* Send the device number MSB first */
>> +	davinci_mdio_man_send_pattern(data, PHY_BITRANGE, phy_id);
>> +
>> +	/* Send the register number MSB first */
>> +	davinci_mdio_man_send_pattern(data, PHY_BITRANGE, phy_reg);
>> +
>> +	/* Send turn around cycles */
>> +	davinci_mdio_sw_clr_bit(data, MDIO_OE);
>> +
>> +	davinci_mdio_toggle_man_bit(data, MDIO_MDCLK);
>> +
>> +	ack = davinci_mdio_test_man_bit(data, MDIO_PIN);
>> +	davinci_mdio_toggle_man_bit(data, MDIO_MDCLK);
>> +
>> +	reg = 0;
>> +	if (ack == 0) {
>> +		for (i = MDIO_BITRANGE; i; i = i >> 1) {
>> +			if (davinci_mdio_test_man_bit(data, MDIO_PIN))
>> +				reg |= i;
>> +
>> +			davinci_mdio_toggle_man_bit(data, MDIO_MDCLK);
>> +		}
>> +	} else {
>> +		for (i = MDIO_BITRANGE; i; i = i >> 1)
>> +			davinci_mdio_toggle_man_bit(data, MDIO_MDCLK);
>> +
>> +		reg = 0xFFFF;
>> +	}
>> +
>> +	davinci_mdio_sw_clr_bit(data, MDIO_MDCLK);
>> +	davinci_mdio_sw_set_bit(data, MDIO_MDCLK);
>> +	davinci_mdio_sw_set_bit(data, MDIO_MDCLK);
>> +	davinci_mdio_toggle_man_bit(data, MDIO_MDCLK);
> 
> You appear to of re-invented drivers/net/mdio/mdio-bitbang.c
> 
> If there is a reason this cannot be used, please at least state it in
> the commit message.
>
Thanks for reviewing the patch. Since mdiobb_{read,write}() are exported, I can 
invoke these in my mdio read/write implementation. I will rework and send the v2 patch

>      Andrew

-- 
Regards,
Ravi