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From: Justin Lai <justinlai0215@realtek.com>
To: Ratheesh Kannoth <rkannoth@marvell.com>
CC: "kuba@kernel.org" <kuba@kernel.org>,
        "davem@davemloft.net"
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        "jiri@resnulli.us" <jiri@resnulli.us>,
        "horms@kernel.org" <horms@kernel.org>,
        Ping-Ke Shih <pkshih@realtek.com>, Larry Chiu <larry.chiu@realtek.com>
Subject: RE: [PATCH net-next v20 06/13] rtase: Implement .ndo_start_xmit function
Thread-Topic: [PATCH net-next v20 06/13] rtase: Implement .ndo_start_xmit
 function
Thread-Index: AQHauLdmYuDGRjyaP0maBwRhxExTNLG77l8AgAefqjA=
Date: Wed, 12 Jun 2024 04:20:29 +0000
Message-ID: <4a894465ea0747d08c96282602bcdf6b@realtek.com>
References: <20240607084321.7254-1-justinlai0215@realtek.com>
 <20240607084321.7254-7-justinlai0215@realtek.com>
 <20240607155420.GA3743392@maili.marvell.com>
In-Reply-To: <20240607155420.GA3743392@maili.marvell.com>
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> On 2024-06-07 at 14:13:14, Justin Lai (justinlai0215@realtek.com) wrote:
> > Implement .ndo_start_xmit function to fill the information of the
> > packet to be transmitted into the tx descriptor, and then the hardware
> > will transmit the packet using the information in the tx descriptor.
> > In addition, we also implemented the tx_handler function to enable the
> > tx descriptor to be reused.
> >
> > Signed-off-by: Justin Lai <justinlai0215@realtek.com>
> > ---
> >  .../net/ethernet/realtek/rtase/rtase_main.c   | 285 ++++++++++++++++++
> >  1 file changed, 285 insertions(+)
> >
> > diff --git a/drivers/net/ethernet/realtek/rtase/rtase_main.c
> > b/drivers/net/ethernet/realtek/rtase/rtase_main.c
> > index 23406c195cff..6bdb4edbfbc1 100644
> > --- a/drivers/net/ethernet/realtek/rtase/rtase_main.c
> > +++ b/drivers/net/ethernet/realtek/rtase/rtase_main.c
> > @@ -256,6 +256,68 @@ static void rtase_mark_to_asic(union rtase_rx_desc
> *desc, u32 rx_buf_sz)
> >                  cpu_to_le32(RTASE_DESC_OWN | eor | rx_buf_sz));  }
> >
> > +static u32 rtase_tx_avail(struct rtase_ring *ring) {
> > +     return READ_ONCE(ring->dirty_idx) + RTASE_NUM_DESC -
> > +            READ_ONCE(ring->cur_idx); }
> dirty_idx and cur_idx wont wrap ? its 32bit in size.
>=20
> >
cur_idx and dirty_idx may wrap, but all we want is the difference between
them, so this won't have any effect. In addition, the difference between
the two will not exceed RTASE_NUM_DESC, and dirty_idx will not exceed
cur_idx, so the calculation won't go wrong.