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net: mvneta: fix handling of the Tx descriptor counter

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The mvneta controller provides a 8-bit register to update the pending
Tx descriptor counter. Then, a maximum of 255 Tx descriptors can be
added at once. In the current code the mvneta_txq_pend_desc_add function
assumes the caller takes care of this limit. But it is not the case. In
some situations (xmit_more flag), more than 255 descriptors are added.
When this happens, the Tx descriptor counter register is updated with a
wrong value, which breaks the whole Tx queue management.

This patch fixes the issue by allowing the mvneta_txq_pend_desc_add
function to process more than 255 Tx descriptors.

Fixes: 2a90f7e1d5d0 ("net: mvneta: add xmit_more support")
Cc: stable@vger.kernel.org # 4.11+
Signed-off-by: Simon Guinot <simon.guinot@sequanux.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Simon Guinot 2017-11-13 16:27:02 +01:00 committed by David S. Miller
parent 096d1dd0f0
commit 0d63785c6b
1 changed files with 8 additions and 5 deletions
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13
drivers/net/ethernet/marvell/mvneta.c
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@ -816,11 +816,14 @@ static void mvneta_txq_pend_desc_add(struct mvneta_port *pp,
{
u32 val;
/* Only 255 descriptors can be added at once ; Assume caller
* process TX desriptors in quanta less than 256
*/
val = pend_desc + txq->pending;
mvreg_write(pp, MVNETA_TXQ_UPDATE_REG(txq->id), val);
pend_desc += txq->pending;
/* Only 255 Tx descriptors can be added at once */
do {
val = min(pend_desc, 255);
mvreg_write(pp, MVNETA_TXQ_UPDATE_REG(txq->id), val);
pend_desc -= val;
} while (pend_desc > 0);
txq->pending = 0;
}