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| author | Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com> | 2025-10-17 16:18:30 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-10-29 13:59:59 +0100 |
| commit | 14b68ab4f671855c2cc1c0094c139a32d33854be (patch) | |
| tree | 345a354bf72a72aed2b1e8d4d5cc1e5a7e046032 /drivers | |
| parent | a8749742e6dc46ee1419d757240173d4487ff9df (diff) | |
| download | linux-14b68ab4f671855c2cc1c0094c139a32d33854be.tar.gz linux-14b68ab4f671855c2cc1c0094c139a32d33854be.tar.bz2 linux-14b68ab4f671855c2cc1c0094c139a32d33854be.zip | |
net: ravb: Ensure memory write completes before ringing TX doorbell
commit 706136c5723626fcde8dd8f598a4dcd251e24927 upstream.
Add a final dma_wmb() barrier before triggering the transmit request
(TCCR_TSRQ) to ensure all descriptor and buffer writes are visible to
the DMA engine.
According to the hardware manual, a read-back operation is required
before writing to the doorbell register to guarantee completion of
previous writes. Instead of performing a dummy read, a dma_wmb() is
used to both enforce the same ordering semantics on the CPU side and
also to ensure completion of writes.
Fixes: c156633f1353 ("Renesas Ethernet AVB driver proper")
Cc: stable@vger.kernel.org
Co-developed-by: Fabrizio Castro <fabrizio.castro.jz@renesas.com>
Signed-off-by: Fabrizio Castro <fabrizio.castro.jz@renesas.com>
Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Link: https://patch.msgid.link/20251017151830.171062-5-prabhakar.mahadev-lad.rj@bp.renesas.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/net/ethernet/renesas/ravb_main.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c index 3cc312a526d9..c3b9281885e3 100644 --- a/drivers/net/ethernet/renesas/ravb_main.c +++ b/drivers/net/ethernet/renesas/ravb_main.c @@ -1602,6 +1602,14 @@ static netdev_tx_t ravb_start_xmit(struct sk_buff *skb, struct net_device *ndev) } else { desc->die_dt = DT_FSINGLE; } + + /* Before ringing the doorbell we need to make sure that the latest + * writes have been committed to memory, otherwise it could delay + * things until the doorbell is rang again. + * This is in replacement of the read operation mentioned in the HW + * manuals. + */ + dma_wmb(); ravb_modify(ndev, TCCR, TCCR_TSRQ0 << q, TCCR_TSRQ0 << q); priv->cur_tx[q] += num_tx_desc; |