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SubjectRe: [PATCH 4/5] net: macb: WoL support for GEM type of Ethernet controller
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On 16/04/2020 at 19:44, nicolas.ferre@microchip.com wrote:
> From: Nicolas Ferre <nicolas.ferre@microchip.com>
>
> Adapt the Wake-on-Lan feature to the Cadence GEM Ethernet controller.
> This controller has different register layout and cannot be handled by
> previous code.
> We disable completely interrupts on all the queues but the queue 0.
> Handling of WoL interrupt is done in another interrupt handler
> positioned depending on the controller version used, just between
> suspend() and resume() calls.
> It allows to lower pressure on the generic interrupt hot path by
> removing the need to handle 2 tests for each IRQ: the first figuring out
> the controller revision, the second for actually knowing if the WoL bit
> is set.
>
> Queue management in suspend()/resume() functions inspired from RFC patch
> by Harini Katakam <harinik@xilinx.com>, thanks!
>
> Signed-off-by: Nicolas Ferre <nicolas.ferre@microchip.com>
> ---
> drivers/net/ethernet/cadence/macb.h | 3 +
> drivers/net/ethernet/cadence/macb_main.c | 121 ++++++++++++++++++++---
> 2 files changed, 109 insertions(+), 15 deletions(-)

[..]

> @@ -4534,23 +4564,56 @@ static int __maybe_unused macb_suspend(struct device *dev)
> struct macb_queue *queue = bp->queues;
> unsigned long flags;
> unsigned int q;
> + int err;
>
> if (!netif_running(netdev))
> return 0;
>
> if (bp->wol & MACB_WOL_ENABLED) {
> - macb_writel(bp, IER, MACB_BIT(WOL));
> - macb_writel(bp, WOL, MACB_BIT(MAG));
> - enable_irq_wake(bp->queues[0].irq);
> - netif_device_detach(netdev);
> - } else {
> - netif_device_detach(netdev);
> + spin_lock_irqsave(&bp->lock, flags);
> + /* Flush all status bits */
> + macb_writel(bp, TSR, -1);
> + macb_writel(bp, RSR, -1);
> for (q = 0, queue = bp->queues; q < bp->num_queues;
> - ++q, ++queue)
> - napi_disable(&queue->napi);
> - rtnl_lock();
> - phylink_stop(bp->phylink);
> - rtnl_unlock();
> + ++q, ++queue) {
> + /* Disable all interrupts */
> + queue_writel(queue, IDR, -1);
> + queue_readl(queue, ISR);
> + if (bp->caps & MACB_CAPS_ISR_CLEAR_ON_WRITE)
> + queue_writel(queue, ISR, -1);
> + }
> + /* Change interrupt handler and
> + * Enable WoL IRQ on queue 0
> + */
> + if (macb_is_gem(bp)) {
> + devm_free_irq(dev, bp->queues[0].irq, bp->queues);
> + err = devm_request_irq(dev, bp->queues[0].irq, gem_wol_interrupt,
> + IRQF_SHARED, netdev->name, bp->queues);
> + if (err) {
> + dev_err(dev,
> + "Unable to request IRQ %d (error %d)\n",
> + bp->queues[0].irq, err);
> + return err;
> + }
> + queue_writel(bp->queues, IER, GEM_BIT(WOL));
> + gem_writel(bp, WOL, MACB_BIT(MAG));
> + } else {
> + queue_writel(bp->queues, IER, MACB_BIT(WOL));
> + macb_writel(bp, WOL, MACB_BIT(MAG));
> + }
> + spin_unlock_irqrestore(&bp->lock, flags);
> +
> + enable_irq_wake(bp->queues[0].irq);
> + }
> +
> + netif_device_detach(netdev);
> + for (q = 0, queue = bp->queues; q < bp->num_queues;
> + ++q, ++queue)
> + napi_disable(&queue->napi);
> +
> + if (!(bp->wol & MACB_WOL_ENABLED)) {
> + phy_stop(netdev->phydev);
> + phy_suspend(netdev->phydev);

Bug here: you must read:

rtnl_lock();
phylink_stop(bp->phylink);
rtnl_unlock();

Instead of the 2 previous lines. I'll correct in v2.

Sorry for the regression.


> spin_lock_irqsave(&bp->lock, flags);
> macb_reset_hw(bp);
> spin_unlock_irqrestore(&bp->lock, flags);
> @@ -4575,20 +4638,48 @@ static int __maybe_unused macb_resume(struct device *dev)

[..]
BTW: I have issue having a real resume event from the phy with this
series. I'm investigating that but didn't find anything for now.

Observation #1: when the WoL is not enabled, I don't have link issue.
But the path in suspend/resume is far more intrusive in phy state.

Observation #2: when WoL is enabled, I need to do a full ifdown/ifup
sequence for gain access again to the link:

ip link show eth0
2: eth0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast
state DOWN mode DEFAULT group default qlen 1000
link/ether 54:10:ec:be:50:b0 brd ff:ff:ff:ff:ff:ff

ifdown eth0 && ifup eth0

ip link show eth0
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast
state UP mode DEFAULT group default qlen 1000
link/ether 54:10:ec:be:50:b0 brd ff:ff:ff:ff:ff:ff

Observation #3: I didn't experience this behavior while playing with the
WoL on my 4.19 kernel before porting to Mainline.

Best regards,
--
Nicolas Ferre

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