RE: [PATCH v2 01/10] net/ngbe: fix Rx buffer size in configure register

["Jiawen Wu" <jiawenwu@trustnetic.com>]

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 = (uint16_t)(rte_pktmbuf_data_room_size(rxq->mb_pool) -
> >  			RTE_PKTMBUF_HEADROOM);
> > -		buf_size = ROUND_DOWN(buf_size, 0x1 << 10);
> > +		if (buf_size < 1024)
> > +			buf_size = ROUND_UP(buf_size, 0x1 << 10);
> 
> Back to original problem statement in previous version, can't this cause HW to
> receive packets exceeding the buffer size?
> 
> 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?
> 

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 = RTE_ETH_DEV_TO_PCI(dev);
	struct txgbe_hw *hw = TXGBE_DEV_HW(dev);

	dev_info->min_rx_bufsize = 1024;


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