linux-kernel - Re: [PATCH net-next v2 11/21] net: ravb: Move DBAT configuration to the driver's ndo

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Message-ID: <3aa8a9f5-fe7b-1484-ac89-64b4a1d5face@omp.ru>
Date: Thu, 21 Dec 2023 22:54:52 +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>,
	<richardcochran@...il.com>, <p.zabel@...gutronix.de>,
	<yoshihiro.shimoda.uh@...esas.com>, <wsa+renesas@...g-engineering.com>,
	<geert+renesas@...der.be>
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-next v2 11/21] net: ravb: Move DBAT configuration to
 the driver's ndo_open API

On 12/20/23 2:41 PM, claudiu beznea wrote:

[...]

>>>>>> From: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
>>>>>>
>>>>>> DBAT setup was done in the driver's probe API. As some IP variants switch
>>>>>> to reset mode (and thus registers' content is lost) when setting clocks
>>>>>> (due to module standby functionality) to be able to implement runtime PM
>>>>>> move the DBAT configuration in the driver's ndo_open API.
>>>>>>
>>>>>> This commit prepares the code for the addition of runtime PM.
>>>>>>
>>>>>> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
>>>>>
>>>>> Reviewed-by: Sergey Shtylyov <s.shtylyov@....ru>
>>>>>
>>>>> [...]
>>>>>> diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c
>>>>>> index 04eaa1967651..6b8ca08be35e 100644
>>>>>> --- a/drivers/net/ethernet/renesas/ravb_main.c
>>>>>> +++ b/drivers/net/ethernet/renesas/ravb_main.c
>>>>>> @@ -1822,6 +1822,7 @@ static int ravb_open(struct net_device *ndev)
>>>>>>  		napi_enable(&priv->napi[RAVB_NC]);
>>>>>>  
>>>>>>  	ravb_set_delay_mode(ndev);
>>>>>> +	ravb_write(ndev, priv->desc_bat_dma, DBAT);
>>>>
>>>>    Looking at it again, I suspect this belong in ravb_dmac_init()...
>>>
>>> ravb_dmac_init() is called from multiple places in this driver, e.g.,
>>
>>    It's purpose is to configure AVB-DMAC and DBAT is the AVB-DMAC register,
>> right?
> 
> It is. But it is pointless to configure it more than one time after
> ravb_open() has been called as the register content is not changed until IP
> enters reset mode (though ravb_close() now).

   The same is true for the most registers set by ravb_dmac_init()!

[...]

MBR, Sergey