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

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Date: Sun, 17 Dec 2023 14:54:18 +0200
From: claudiu beznea <claudiu.beznea@...on.dev>
To: Sergey Shtylyov <s.shtylyov@....ru>, 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 15.12.2023 22:01, Sergey Shtylyov wrote:
> On 12/15/23 12:03 AM, Sergey Shtylyov 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.,
ravb_set_ringparam(), ravb_tx_timeout_work(). I'm afraid we may broke the
behavior of these if DBAT setup is moved in ravb_dmac_init(). This is also
valid for setting delay (see patch 10/12).

> 
>>>  
>>>  	/* Device init */
>>>  	error = ravb_dmac_init(ndev);
> [...]
> 
> MBR, Sergey