Re: [PATCH] mlx4_en: fix transmit of packages when blue frame is enabled

On Tue, 2011-10-04 at 17:26 -0300, Thadeu Lima de Souza Cascardo wrote:

        if (ring->bf_enabled && desc_size <= MAX_BF && !bounce &&
!vlan_tag) {
                *(u32 *) (&tx_desc->ctrl.vlan_tag) |=
ring->doorbell_qpn;

Could this have endianness problems ?

                op_own |= htonl((bf_index & 0xffff) << 8);

Probably better to use cpu_to_be/lexx() here. Also make sure your
descriptors are defined with the appropriate __beXX or __leXX types
so sparse can tell you when you get this wrong

                /* Ensure new descirptor hits memory
                * before setting ownership of this descriptor to HW */
                wmb();
                tx_desc->ctrl.owner_opcode = op_own;

                wmb();

                mlx4_bf_copy(ring->bf.reg + ring->bf.offset, (unsigned
long *) &tx_desc->ctrl,
                     desc_size);

What does the above do ?

                wmb();

                ring->bf.offset ^= ring->bf.buf_size;

Is this HW visible ? It's a bit odd, are you doing double bufferring and
trying to flip a bit ? If it's HW visible, is endian correct ?
 
        } else {

                /* Ensure new descirptor hits memory
                * before setting ownership of this descriptor to HW */
                wmb();
                tx_desc->ctrl.owner_opcode = op_own;
-               wmb();
-               writel(ring->doorbell_qpn, ring->bf.uar->map +
MLX4_SEND_DOORBELL);
        }

+       wmb();
+       writel(ring->doorbell_qpn, ring->bf.uar->map +
MLX4_SEND_DOORBELL);
+
---

Cheers,
Ben.