netdev - Re: [PATCH net-next v2 21/21] net: ravb: Add runtime PM support

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Date: Sat, 16 Dec 2023 23:56:05 +0300
From: Sergey Shtylyov <s.shtylyov@....ru>
To: Claudiu <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 21/21] net: ravb: Add runtime PM support

On 12/14/23 2:46 PM, Claudiu wrote:

> From: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
> 
> Add runtime PM support for the ravb driver. As the driver is used by
> different IP variants, with different behaviors, to be able to have the
> runtime PM support available for all devices, the preparatory commits
> moved all the resources parsing and allocations in the driver's probe
> function and kept the settings for ravb_open(). This is due to the fact
> that on some IP variants-platforms tuples disabling/enabling the clocks
> will switch the IP to the reset operation mode where registers' content is

   The register contents.

> lost and reconfiguration needs to be done. For this the rabv_open()
> function enables the clocks, switches the IP to configuration mode, applies
> all the registers settings and switches the IP to the operational mode. At
> the end of ravb_open() IP is ready to send/receive data.
> 
> In ravb_close() necessary reverts are done (compared with ravb_open()), the
> IP is switched to reset mode and clocks are disabled.
> 
> The ethtool APIs or IOCTLs that might execute while the interface is down
> are either cached (and applied in ravb_open()) or rejected (as at that time
> the IP is in reset mode). Keeping the IP in the reset mode also increases
> the power saved (according to the hardware manual).
> 
> 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 9ff943dff522..0733b63ff910 100644
> --- a/drivers/net/ethernet/renesas/ravb_main.c
> +++ b/drivers/net/ethernet/renesas/ravb_main.c
> @@ -1839,16 +1839,21 @@ static int ravb_open(struct net_device *ndev)
>  {
>  	struct ravb_private *priv = netdev_priv(ndev);
>  	const struct ravb_hw_info *info = priv->info;
> +	struct device *dev = &priv->pdev->dev;
>  	int error;
>  
>  	napi_enable(&priv->napi[RAVB_BE]);
>  	if (info->nc_queues)
>  		napi_enable(&priv->napi[RAVB_NC]);
>  
> +	error = pm_runtime_resume_and_get(dev);
> +	if (error < 0)
> +		goto out_napi_off;
> +

   Note that sh_eth.c does this before enabling NAPI...

[...]

MBR, Sergey