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net: socionext: clear rx irq correctly 

commit 63ae7949e9 ("net: socionext: Use descriptor info instead of MMIO reads on Rx")
removed constant mmio reads from the driver and started using a descriptor
field to check if packet should be processed.
This lead the napi rx handler being constantly called while no packets
needed processing and ksoftirq getting 100% cpu usage. Issue one mmio read
to clear the irq correcty after processing packets

Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Reported-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Tested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Ilias Apalodimas 2018-10-11 15:28:26 +03:00 committed by David S. Miller
parent 2645060834
commit 2a1e89df78
1 changed files with 4 additions and 1 deletions
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5
drivers/net/ethernet/socionext/netsec.c
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@ -735,8 +735,11 @@ static int netsec_process_rx(struct netsec_priv *priv, int budget)
u16 idx = dring->tail;
struct netsec_de *de = dring->vaddr + (DESC_SZ * idx);
if (de->attr & (1U << NETSEC_RX_PKT_OWN_FIELD))
if (de->attr & (1U << NETSEC_RX_PKT_OWN_FIELD)) {
/* reading the register clears the irq */
netsec_read(priv, NETSEC_REG_NRM_RX_PKTCNT);
break;
}
/* This barrier is needed to keep us from reading
* any other fields out of the netsec_de until we have