Commit 41b7e4c3 authored by Steve Hodgson's avatar Steve Hodgson Committed by David S. Miller
Browse files

sfc: Extend the legacy interrupt workarounds 



Siena has two problems with legacy interrupts:
  1. There is no synchronisation between the ISR read completion,
     and the interrupt deassert message.
  2. A downstream read at the "wrong" moment can return 0, and
     suppress generating the next interrupt.

Falcon should suffer from both of these, and it appears it does.
Enable EFX_WORKAROUND_15783 on Falcon as well.

Also, when we see queues == 0, ensure we always schedule or rearm
every event queue.

Signed-off-by: default avatarBen Hutchings <bhutchings@solarflare.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent b7b40eeb

drivers/net/sfc/nic.c

+9 −14
Original line number Diff line number Diff line
@@ -1356,33 +1356,28 @@ static irqreturn_t efx_legacy_interrupt(int irq, void *dev_id) 
		}

		result = IRQ_HANDLED;



	} else if (EFX_WORKAROUND_15783(efx) &&

		   efx->irq_zero_count++ == 0) {

	} else if (EFX_WORKAROUND_15783(efx)) {

		efx_qword_t *event;



		/* Ensure we rearm all event queues */

		/* We can't return IRQ_HANDLED more than once on seeing ISR=0

		 * because this might be a shared interrupt. */

		if (efx->irq_zero_count++ == 0)

			result = IRQ_HANDLED;



		/* Ensure we schedule or rearm all event queues */

		efx_for_each_channel(channel, efx) {

			event = efx_event(channel, channel->eventq_read_ptr);

			if (efx_event_present(event))

				efx_schedule_channel(channel);

			else

				efx_nic_eventq_read_ack(channel);

		}



		result = IRQ_HANDLED;

	}



	if (result == IRQ_HANDLED) {

		efx->last_irq_cpu = raw_smp_processor_id();

		EFX_TRACE(efx, "IRQ %d on CPU %d status " EFX_DWORD_FMT "\n",

			  irq, raw_smp_processor_id(), EFX_DWORD_VAL(reg));

	} else if (EFX_WORKAROUND_15783(efx)) {

		/* We can't return IRQ_HANDLED more than once on seeing ISR0=0

		 * because this might be a shared interrupt, but we do need to

		 * check the channel every time and preemptively rearm it if

		 * it's idle. */

		efx_for_each_channel(channel, efx) {

			if (!channel->work_pending)

				efx_nic_eventq_read_ack(channel);

		}

	}



	return result;

drivers/net/sfc/workarounds.h

+1 −1
Original line number Diff line number Diff line
@@ -37,7 +37,7 @@ 
/* Truncated IPv4 packets can confuse the TX packet parser */

#define EFX_WORKAROUND_15592 EFX_WORKAROUND_FALCON_AB

/* Legacy ISR read can return zero once */

#define EFX_WORKAROUND_15783 EFX_WORKAROUND_SIENA

#define EFX_WORKAROUND_15783 EFX_WORKAROUND_ALWAYS

/* Legacy interrupt storm when interrupt fifo fills */

#define EFX_WORKAROUND_17213 EFX_WORKAROUND_SIENA

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