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Date: Wed, 22 Nov 2023 19:25:48 +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>,
<p.zabel@...gutronix.de>, <yoshihiro.shimoda.uh@...esas.com>,
<geert+renesas@...der.be>, <wsa+renesas@...g-engineering.com>,
<biju.das.jz@...renesas.com>, <prabhakar.mahadev-lad.rj@...renesas.com>,
<sergei.shtylyov@...entembedded.com>, <mitsuhiro.kimura.kc@...esas.com>,
<masaru.nagai.vx@...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 13/13] net: ravb: Add runtime PM support
On 11/20/23 11:46 AM, Claudiu wrote:
> From: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
> RZ/G3S supports enabling/disabling clocks for its modules (including
> Ethernet module). For this commit adds runtime PM support which
> relies on PM domain to enable/disable Ethernet clocks.
That's not exactly something new in RZ/G3S. The ravb driver has unconditional
RPM calls already in the probe() and remove() methods... And the sh_eth driver
has RPM support since 2009...
> At the end of probe ravb_pm_runtime_put() is called which will turn
I'd suggest a shorter name, like ravb_rpm_put() but (looking at this function)
it doesn't seem hardly needed...
> off the Ethernet clocks (if no other request arrives at the driver).
> After that if the interface is brought up (though ravb_open()) then
> the clocks remain enabled until interface is brought down (operation
> done though ravb_close()).
>
> If any request arrives to the driver while the interface is down the
> clocks are enabled to serve the request and then disabled.
>
> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
> ---
> drivers/net/ethernet/renesas/ravb.h | 1 +
> drivers/net/ethernet/renesas/ravb_main.c | 99 ++++++++++++++++++++++--
> 2 files changed, 93 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/net/ethernet/renesas/ravb.h b/drivers/net/ethernet/renesas/ravb.h
> index c2d8d890031f..50f358472aab 100644
> --- a/drivers/net/ethernet/renesas/ravb.h
> +++ b/drivers/net/ethernet/renesas/ravb.h
> @@ -1044,6 +1044,7 @@ struct ravb_hw_info {
> unsigned magic_pkt:1; /* E-MAC supports magic packet detection */
> unsigned half_duplex:1; /* E-MAC supports half duplex mode */
> unsigned refclk_in_pd:1; /* Reference clock is part of a power domain. */
> + unsigned rpm:1; /* Runtime PM available. */
No, I don't think this flag makes any sense. We should support RPM
unconditionally...
[...]
> diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c
> index f4634ac0c972..d70ed7e5f7f6 100644
> --- a/drivers/net/ethernet/renesas/ravb_main.c
> +++ b/drivers/net/ethernet/renesas/ravb_main.c
> @@ -145,12 +145,41 @@ static void ravb_read_mac_address(struct device_node *np,
[...]
> +static void ravb_pm_runtime_put(struct ravb_private *priv)
> +{
> + const struct ravb_hw_info *info = priv->info;
> + struct device *dev = &priv->pdev->dev;
> +
> + if (!info->rpm)
> + return;
> +
> + pm_runtime_mark_last_busy(dev);
Not very familiar with RPM... what's this for?
> + pm_runtime_put_autosuspend(dev);
Why not the usual pm_runtime_put()?
> +}
> +
> static void ravb_mdio_ctrl(struct mdiobb_ctrl *ctrl, u32 mask, int set)
> {
> struct ravb_private *priv = container_of(ctrl, struct ravb_private,
> mdiobb);
> + int ret;
> +
> + ret = ravb_pm_runtime_get(priv);
> + if (ret < 0)
> + return;
>
> ravb_modify(priv->ndev, PIR, mask, set ? mask : 0);
> +
> + ravb_pm_runtime_put(priv);
Hmm, does this even work? :-/ Do the MDIO bits retain the values while
the AVB core is not clocked or even powered down?
Note that the sh_eth driver has RPM calls in the {read|write}_c{22?45}()
methods which do the full register read/write while the core is powere up
and clocked...
[...]
> @@ -2064,6 +2107,11 @@ static struct net_device_stats *ravb_get_stats(struct net_device *ndev)
> struct ravb_private *priv = netdev_priv(ndev);
> const struct ravb_hw_info *info = priv->info;
> struct net_device_stats *nstats, *stats0, *stats1;
> + int ret;
> +
> + ret = ravb_pm_runtime_get(priv);
> + if (ret < 0)
> + return NULL;
Hm, sh_eth.c doesn't have any RPM calls in this method. Again, do
the hardware counters remain valid across powering the MAC core down?
[...]
> @@ -2115,11 +2165,18 @@ static void ravb_set_rx_mode(struct net_device *ndev)
> {
> struct ravb_private *priv = netdev_priv(ndev);
> unsigned long flags;
> + int ret;
> +
> + ret = ravb_pm_runtime_get(priv);
> + if (ret < 0)
> + return;
Hm, sh_eth.c doesn't have any RPM calls in this method either.
Does changing the promiscous mode have sense for an offlined interface?
[...]
> @@ -2187,6 +2244,11 @@ static int ravb_close(struct net_device *ndev)
> if (info->nc_queues)
> ravb_ring_free(ndev, RAVB_NC);
>
> + /* Note that if RPM is enabled on plaforms with ccc_gac=1 this needs to be
It's "platforms". :-)
> skipped and
Overly long line?
> + * added to suspend function after PTP is stopped.
I guess we'll have to do that because RPM is actually not RZ/G3
specific...
> + */
> + ravb_pm_runtime_put(priv);
> +
> return 0;
> }
>
> @@ -2636,6 +2699,12 @@ static int ravb_probe(struct platform_device *pdev)
> if (error)
> return error;
>
> + info = of_device_get_match_data(&pdev->dev);
> +
> + if (info->rpm) {
> + pm_runtime_set_autosuspend_delay(&pdev->dev, 100);
Why exactly 100 ms?
> + pm_runtime_use_autosuspend(&pdev->dev);
> + }
Before calling pm_runtime_enable()?
> pm_runtime_enable(&pdev->dev);
[...]
> @@ -2880,6 +2950,8 @@ static int ravb_probe(struct platform_device *pdev)
> pm_runtime_put(&pdev->dev);
> pm_runtime_disable:
> pm_runtime_disable(&pdev->dev);
> + if (info->rpm)
> + pm_runtime_dont_use_autosuspend(&pdev->dev);
After calling pm_runtime_disable()?
[...]
> @@ -2908,6 +2985,8 @@ static void ravb_remove(struct platform_device *pdev)
> priv->desc_bat_dma);
> pm_runtime_put_sync(&pdev->dev);
> pm_runtime_disable(&pdev->dev);
> + if (info->rpm)
> + pm_runtime_dont_use_autosuspend(&pdev->dev);
After calling pm_runtime_disable()?
[...]
MBR, Sergey
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