[dpdk-dev] [PATCH 02/53] net/sfc/base: do not use Tx desc push with TSO descriptors
Andrew Rybchenko
arybchenko at solarflare.com
Thu Nov 16 09:03:50 CET 2017
From: Mark Spender <mspender at solarflare.com>
Pushing TSO option descriptors is unsafe if pacer bypass is enabled,
so to make sure that doesn't happen never push TSO option descriptors.
Signed-off-by: Mark Spender <mspender at solarflare.com>
Signed-off-by: Andrew Rybchenko <arybchenko at solarflare.com>
---
drivers/net/sfc/base/ef10_tx.c | 56 ++++++++++++++++++++++++++++++++----------
1 file changed, 43 insertions(+), 13 deletions(-)
diff --git a/drivers/net/sfc/base/ef10_tx.c b/drivers/net/sfc/base/ef10_tx.c
index 211d265..2666943 100644
--- a/drivers/net/sfc/base/ef10_tx.c
+++ b/drivers/net/sfc/base/ef10_tx.c
@@ -473,9 +473,9 @@ ef10_tx_qpost(
}
/*
- * This improves performance by pushing a TX descriptor at the same time as the
- * doorbell. The descriptor must be added to the TXQ, so that can be used if the
- * hardware decides not to use the pushed descriptor.
+ * This improves performance by, when possible, pushing a TX descriptor at the
+ * same time as the doorbell. The descriptor must be added to the TXQ, so that
+ * can be used if the hardware decides not to use the pushed descriptor.
*/
void
ef10_tx_qpush(
@@ -495,16 +495,46 @@ ef10_tx_qpush(
offset = id * sizeof (efx_qword_t);
EFSYS_MEM_READQ(etp->et_esmp, offset, &desc);
- EFX_POPULATE_OWORD_3(oword,
- ERF_DZ_TX_DESC_WPTR, wptr,
- ERF_DZ_TX_DESC_HWORD, EFX_QWORD_FIELD(desc, EFX_DWORD_1),
- ERF_DZ_TX_DESC_LWORD, EFX_QWORD_FIELD(desc, EFX_DWORD_0));
-
- /* Guarantee ordering of memory (descriptors) and PIO (doorbell) */
- EFX_DMA_SYNC_QUEUE_FOR_DEVICE(etp->et_esmp, etp->et_mask + 1, wptr, id);
- EFSYS_PIO_WRITE_BARRIER();
- EFX_BAR_TBL_DOORBELL_WRITEO(enp, ER_DZ_TX_DESC_UPD_REG, etp->et_index,
- &oword);
+
+ /*
+ * Bug 65776: TSO option descriptors cannot be pushed if pacer bypass is
+ * enabled on the event queue this transmit queue is attached to.
+ *
+ * To ensure the code is safe, it is easiest to simply test the type of
+ * the descriptor to push, and only push it is if it not a TSO option
+ * descriptor.
+ */
+ if ((EFX_QWORD_FIELD(desc, ESF_DZ_TX_DESC_IS_OPT) != 1) ||
+ (EFX_QWORD_FIELD(desc, ESF_DZ_TX_OPTION_TYPE) !=
+ ESE_DZ_TX_OPTION_DESC_TSO)) {
+ /* Push the descriptor and update the wptr. */
+ EFX_POPULATE_OWORD_3(oword, ERF_DZ_TX_DESC_WPTR, wptr,
+ ERF_DZ_TX_DESC_HWORD, EFX_QWORD_FIELD(desc, EFX_DWORD_1),
+ ERF_DZ_TX_DESC_LWORD, EFX_QWORD_FIELD(desc, EFX_DWORD_0));
+
+ /* Ensure ordering of memory (descriptors) and PIO (doorbell) */
+ EFX_DMA_SYNC_QUEUE_FOR_DEVICE(etp->et_esmp, etp->et_mask + 1,
+ wptr, id);
+ EFSYS_PIO_WRITE_BARRIER();
+ EFX_BAR_TBL_DOORBELL_WRITEO(enp, ER_DZ_TX_DESC_UPD_REG,
+ etp->et_index, &oword);
+ } else {
+ efx_dword_t dword;
+
+ /*
+ * Only update the wptr. This is signalled to the hardware by
+ * only writing one DWORD of the doorbell register.
+ */
+ EFX_POPULATE_OWORD_1(oword, ERF_DZ_TX_DESC_WPTR, wptr);
+ dword = oword.eo_dword[2];
+
+ /* Ensure ordering of memory (descriptors) and PIO (doorbell) */
+ EFX_DMA_SYNC_QUEUE_FOR_DEVICE(etp->et_esmp, etp->et_mask + 1,
+ wptr, id);
+ EFSYS_PIO_WRITE_BARRIER();
+ EFX_BAR_TBL_WRITED2(enp, ER_DZ_TX_DESC_UPD_REG,
+ etp->et_index, &dword, B_FALSE);
+ }
}
__checkReturn efx_rc_t
--
2.7.4
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