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From: =?utf-8?b?Smlhd2VuIFd1?= <jiawenwu@trustnetic.com>
To: "'Ferruh Yigit'" <ferruh.yigit@amd.com>,
	<dev@dpdk.org>
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References: <20230118060039.3074016-1-jiawenwu@trustnetic.com>
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In-Reply-To: <ee62c341-8221-0ca5-df15-5664d50ca80a@amd.com>
Subject: RE: [PATCH v2 01/10] net/ngbe: fix Rx buffer size in configure
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Date: Thu, 9 Feb 2023 17:00:13 +0800
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On Wednesday, February 8, 2023 6:28 PM, Ferruh Yigit wrote:
> On 2/2/2023 9:21 AM, Jiawen Wu wrote:
> > When buffer size is less than 1K, round down makes it 0, which is an
> > error value.
> >
> > Fixes: 62fc35e63d0e ("net/ngbe: support Rx queue start/stop")
> > Cc: stable@dpdk.org
> >
> > Signed-off-by: Jiawen Wu <jiawenwu@trustnetic.com>
> > ---
> >  drivers/net/ngbe/ngbe_rxtx.c | 5 ++++-
> >  1 file changed, 4 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/net/ngbe/ngbe_rxtx.c
> > b/drivers/net/ngbe/ngbe_rxtx.c index 9fd24fa444..9a646cb6a7 100644
> > --- a/drivers/net/ngbe/ngbe_rxtx.c
> > +++ b/drivers/net/ngbe/ngbe_rxtx.c
> > @@ -2944,7 +2944,10 @@ ngbe_dev_rx_init(struct rte_eth_dev *dev)
> >  		 */
> >  		buf_size =3D (uint16_t)(rte_pktmbuf_data_room_size(rxq->mb_pool) =
-
> >  			RTE_PKTMBUF_HEADROOM);
> > -		buf_size =3D ROUND_DOWN(buf_size, 0x1 << 10);
> > +		if (buf_size < 1024)
> > +			buf_size =3D ROUND_UP(buf_size, 0x1 << 10);
>=20
> Back to original problem statement in previous version, can't this =
cause HW to
> receive packets exceeding the buffer size?
>=20
> If HW accepts buffer size in multiple of 1K, does this mean any buffer =
size less than
> 1K is an error condition for this HW?
>=20

After rechecking the code, the minimum buffer size is limited to 1K by =
the txgbe/ngbe [1].
I think v1 patch for txgbe is enough.

[1]
static int
txgbe_dev_info_get(struct rte_eth_dev *dev, struct rte_eth_dev_info =
*dev_info)
{
	struct rte_pci_device *pci_dev =3D RTE_ETH_DEV_TO_PCI(dev);
	struct txgbe_hw *hw =3D TXGBE_DEV_HW(dev);

	dev_info->min_rx_bufsize =3D 1024;


> > +		else
> > +			buf_size =3D ROUND_DOWN(buf_size, 0x1 << 10);
> >  		srrctl |=3D NGBE_RXCFG_PKTLEN(buf_size);
> >
> >  		wr32(hw, NGBE_RXCFG(rxq->reg_idx), srrctl);
>=20
>=20