netdev - Re: [PATCH net v2 1/1] net: ravb: Wait for operation mode to be applied

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Date: Thu, 28 Dec 2023 22:07:30 +0300
From: Sergey Shtylyov <s.shtylyov@....ru>
To: claudiu beznea <claudiu.beznea@...on.dev>, <davem@...emloft.net>,
	<edumazet@...gle.com>, <kuba@...nel.org>, <pabeni@...hat.com>,
	<yoshihiro.shimoda.uh@...esas.com>, <wsa+renesas@...g-engineering.com>,
	<mitsuhiro.kimura.kc@...esas.com>
CC: <netdev@...r.kernel.org>, <linux-renesas-soc@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, Claudiu Beznea
	<claudiu.beznea.uj@...renesas.com>
Subject: Re: [PATCH net v2 1/1] net: ravb: Wait for operation mode to be
 applied

On 12/27/23 1:10 PM, claudiu beznea wrote:

[...]

>>> From: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
>>>
>>> CSR.OPS bits specify the current operating mode and (according to
>>> documentation) they are updated by HW when the operating mode change
>>> request is processed. To comply with this check CSR.OPS before proceeding.
>>>
>>> Commit introduces ravb_set_opmode() that does all the necessities for
>>> setting the operating mode (set DMA.CCC and wait for CSR.OPS) and call it
>>> where needed. This should comply with all the HW manuals requirements as
>>> different manual variants specify that different modes need to be checked
>>> in CSR.OPS when setting DMA.CCC.
>>>
>>> Fixes: c156633f1353 ("Renesas Ethernet AVB driver proper")
>>> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
>>> ---
>>>  drivers/net/ethernet/renesas/ravb_main.c | 52 ++++++++++++++----------
>>>  1 file changed, 31 insertions(+), 21 deletions(-)
>>>
>>> diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c
>>> index 664eda4b5a11..ae99d035a3b6 100644
>>> --- a/drivers/net/ethernet/renesas/ravb_main.c
>>> +++ b/drivers/net/ethernet/renesas/ravb_main.c
>>> @@ -66,14 +66,15 @@ int ravb_wait(struct net_device *ndev, enum ravb_reg reg, u32 mask, u32 value)
>>>  	return -ETIMEDOUT;
>>>  }
>>>  
>>> -static int ravb_config(struct net_device *ndev)
>>> +static int ravb_set_opmode(struct net_device *ndev, u32 opmode)
>>
>>    Since you pass the complete CCC register value below, you should
>> rather call the function ravb_set_ccc() and call the parameter opmode
>> ccc.
> 
> This will be confusing. E.g., if renaming it ravb_set_ccc() one would
> expect to set any fields of CCC though this function but this is not true
> as ravb_modify() in this function masks only CCC_OPC. The call of:
> 
> error = ravb_set_opmode(ndev, CCC_OPC_CONFIG | CCC_GAC | CCC_CSEL_HPB);
> 
> bellow is just to comply with datasheet requirements, previous code and at
> the same time re-use this function.

   How about the following then (ugly... but does the job):

	/* Set operating mode */
	if (opmode & ~CCC_OPC)
		ravb_write(ndev, opmode, CCC);
	else
		ravb_modify(ndev, CCC, CCC_OPC, opmode);

   Either that or just don't use ravb_set_opmode() when writing the whole
32-bit value below...

[...]

>>> @@ -2560,21 +2559,23 @@ static int ravb_set_gti(struct net_device *ndev)
[...]
>>
>>>  		/* Set CSEL value */
>>>  		ravb_modify(ndev, CCC, CCC_CSEL, CCC_CSEL_HPB);
>>>  	} else if (info->ccc_gac) {
>>> -		ravb_modify(ndev, CCC, CCC_OPC, CCC_OPC_CONFIG |
>>> -			    CCC_GAC | CCC_CSEL_HPB);
>>> +		error = ravb_set_opmode(ndev, CCC_OPC_CONFIG | CCC_GAC | CCC_CSEL_HPB);

   ... like this?

		ravb_write(ndev, CCC_OPC_CONFIG | CCC_GAC | CCC_CSEL_HPB, CCC);
		error = ravb_wait(ndev, CSR, CSR_OPS, CSR_OPS_CONFIG);

[...]

MBR, Sergey