netdev - Re: [PATCH net-next 1/1] fec: add C45 MDIO read/write support

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Date:   Wed, 21 Aug 2019 11:44:19 +0000
From:   Marco Hartmann <marco.hartmann@....com>
To:     Andy Duan <fugang.duan@....com>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Christian Herber <christian.herber@....com>
Subject: Re: [PATCH net-next 1/1] fec: add C45 MDIO read/write support

On 20.08.19 04:08, Andy Duan wrote:
> From: Marco Hartmann Sent: Tuesday, August 20, 2019 1:11 AM
>> IEEE 802.3ae clause 45 defines a modified MDIO protocol that uses a two
>> staged access model in order to increase the address space.
>>
>> This patch adds support for C45 MDIO read and write accesses, which are
>> used whenever the MII_ADDR_C45 flag in the regnum argument is set.
>> In case it is not set, C22 accesses are used as before.
>>
>> Co-developed-by: Christian Herber <christian.herber@....com>
>> Signed-off-by: Christian Herber <christian.herber@....com>
>> Signed-off-by: Marco Hartmann <marco.hartmann@....com>
>> ---
>>   drivers/net/ethernet/freescale/fec_main.c | 65
>> ++++++++++++++++++++++++++++---
>>   1 file changed, 59 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/net/ethernet/freescale/fec_main.c
>> b/drivers/net/ethernet/freescale/fec_main.c
>> index c01d3ec3e9af..73f8f9a149a1 100644
>> --- a/drivers/net/ethernet/freescale/fec_main.c
>> +++ b/drivers/net/ethernet/freescale/fec_main.c
>> @@ -208,8 +208,11 @@ MODULE_PARM_DESC(macaddr, "FEC Ethernet
>> MAC address");
>>
>>   /* FEC MII MMFR bits definition */
>>   #define FEC_MMFR_ST		(1 << 30)
>> +#define FEC_MMFR_ST_C45		(0)
>>   #define FEC_MMFR_OP_READ	(2 << 28)
>> +#define FEC_MMFR_OP_READ_C45	(3 << 28)
>>   #define FEC_MMFR_OP_WRITE	(1 << 28)
>> +#define FEC_MMFR_OP_ADDR_WRITE	(0)
>>   #define FEC_MMFR_PA(v)		((v & 0x1f) << 23)
>>   #define FEC_MMFR_RA(v)		((v & 0x1f) << 18)
>>   #define FEC_MMFR_TA		(2 << 16)
>> @@ -1767,7 +1770,7 @@ static int fec_enet_mdio_read(struct mii_bus *bus,
>> int mii_id, int regnum)
>>   	struct fec_enet_private *fep = bus->priv;
>>   	struct device *dev = &fep->pdev->dev;
>>   	unsigned long time_left;
>> -	int ret = 0;
>> +	int ret = 0, frame_start, frame_addr, frame_op;
> 
> Add bool variable:
> 
> bool is_c45 = !!(regnum & MII_ADDR_C45);
>>
>>   	ret = pm_runtime_get_sync(dev);
>>   	if (ret < 0)
>> @@ -1775,9 +1778,36 @@ static int fec_enet_mdio_read(struct mii_bus
>> *bus, int mii_id, int regnum)
>>
>>   	reinit_completion(&fep->mdio_done);
>>
>> +	if (MII_ADDR_C45 & regnum) {
> if (is_c45)
> 
>> +		frame_start = FEC_MMFR_ST_C45;
>> +
>> +		/* write address */
>> +		frame_addr = (regnum >> 16);
>> +		writel(frame_start | FEC_MMFR_OP_ADDR_WRITE |
>> +		       FEC_MMFR_PA(mii_id) | FEC_MMFR_RA(frame_addr) |
>> +		       FEC_MMFR_TA | (regnum & 0xFFFF),
>> +		       fep->hwp + FEC_MII_DATA);
>> +
>> +		/* wait for end of transfer */
>> +		time_left = wait_for_completion_timeout(&fep->mdio_done,
>> +				usecs_to_jiffies(FEC_MII_TIMEOUT));
>> +		if (time_left == 0) {
>> +			netdev_err(fep->netdev, "MDIO address write timeout\n");
>> +			ret  = -ETIMEDOUT;
> 
> Should be:
> goto out;
>> +		}
>> +
>> +		frame_op = FEC_MMFR_OP_READ_C45;
>> +
>> +	} else {
>> +		/* C22 read */
>> +		frame_op = FEC_MMFR_OP_READ;
>> +		frame_start = FEC_MMFR_ST;
>> +		frame_addr = regnum;
>> +	}
>> +
>>   	/* start a read op */
>> -	writel(FEC_MMFR_ST | FEC_MMFR_OP_READ |
>> -		FEC_MMFR_PA(mii_id) | FEC_MMFR_RA(regnum) |
>> +	writel(frame_start | frame_op |
>> +		FEC_MMFR_PA(mii_id) | FEC_MMFR_RA(frame_addr) |
>>   		FEC_MMFR_TA, fep->hwp + FEC_MII_DATA);
>>
>>   	/* wait for end of transfer */
>> @@ -1804,7 +1834,7 @@ static int fec_enet_mdio_write(struct mii_bus *bus,
>> int mii_id, int regnum,
>>   	struct fec_enet_private *fep = bus->priv;
>>   	struct device *dev = &fep->pdev->dev;
>>   	unsigned long time_left;
>> -	int ret;
>> +	int ret, frame_start, frame_addr;
>>
>>   	ret = pm_runtime_get_sync(dev);
>>   	if (ret < 0)
>> @@ -1814,9 +1844,32 @@ static int fec_enet_mdio_write(struct mii_bus
>> *bus, int mii_id, int regnum,
> 
> bool is_c45 = !!(regnum & MII_ADDR_C45);
>>
>>   	reinit_completion(&fep->mdio_done);
>>
>> +	if (MII_ADDR_C45 & regnum) {
> 
> if (!is_c45) {
>> +		frame_start = FEC_MMFR_ST_C45;
>> +
>> +		/* write address */
>> +		frame_addr = (regnum >> 16);
>> +		writel(frame_start | FEC_MMFR_OP_ADDR_WRITE |
>> +		       FEC_MMFR_PA(mii_id) | FEC_MMFR_RA(frame_addr) |
>> +		       FEC_MMFR_TA | (regnum & 0xFFFF),
>> +		       fep->hwp + FEC_MII_DATA);
>> +
>> +		/* wait for end of transfer */
>> +		time_left = wait_for_completion_timeout(&fep->mdio_done,
>> +			usecs_to_jiffies(FEC_MII_TIMEOUT));
>> +		if (time_left == 0) {
>> +			netdev_err(fep->netdev, "MDIO address write timeout\n");
>> +			ret  = -ETIMEDOUT;
> Like mdio read, it should be:
> goto out;
>> +		}
>> +	} else {
>> +		/* C22 write */
>> +		frame_start = FEC_MMFR_ST;
>> +		frame_addr = regnum;
>> +	}
>> +
>>   	/* start a write op */
>> -	writel(FEC_MMFR_ST | FEC_MMFR_OP_WRITE |
>> -		FEC_MMFR_PA(mii_id) | FEC_MMFR_RA(regnum) |
>> +	writel(frame_start | FEC_MMFR_OP_WRITE |
>> +		FEC_MMFR_PA(mii_id) | FEC_MMFR_RA(frame_addr) |
>>   		FEC_MMFR_TA | FEC_MMFR_DATA(value),
>>   		fep->hwp + FEC_MII_DATA);
>>
>> --
>> 2.7.4
> 

Thank you for your feedback,
the fixes are included in v2 of the patch.

Regards,
Marco