netdev - Re: [PATCH 03/25] mlx4_core: add multi-function communication channel

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Date:	Wed, 04 Nov 2009 10:04:59 -0800
From:	Roland Dreier <rdreier@...co.com>
To:	Yevgeny Petrilin <yevgenyp@...lanox.co.il>
Cc:	linux-rdma@...r.kernel.org, netdev@...r.kernel.org,
	liranl@...lanox.co.il, tziporet@...lanox.co.il
Subject: Re: [PATCH 03/25] mlx4_core: add multi-function communication channel


 > --- a/drivers/net/mlx4/cmd.c
 > +++ b/drivers/net/mlx4/cmd.c
 > @@ -41,6 +41,7 @@
 >  #include <asm/io.h>
 >  
 >  #include "mlx4.h"
 > +#include "en_port.h"

Why does core mlx4 command handling end up depending on stuff from en_port.h?

 > +	__be32 status = readl(&priv->mfunc.comm->slave_read);

This can't be endian-clean, can it?  What does sparse with
-D__CHECK_ENDIAN__ say?

 > +	queue_delayed_work(priv->mfunc.comm_wq, &priv->mfunc.comm_work,
 > +						polled ? HZ / 1000 : HZ / 10);

So this is always running at least 10 times a second?  That's a lot of
wakeups on an idle system.  Is there no way to make this event-driven?

And HZ/1000 is going to be 0 if HZ is less than 1000 ... so this is just
going to run continuously in the polling case.

 > +	/* Write command */
 > +	if (cmd == MLX4_COMM_CMD_RESET)
 > +		priv->cmd.comm_toggle = 0;
 > +	else if (++priv->cmd.comm_toggle > 2)
 > +		priv->cmd.comm_toggle = 1;

Is this right?  comm_toggle goes 0, 1, 2, 1, 2, ...?

 > +static struct mlx4_cmd_info {
 > +	u8 opcode;
 > +	u8 has_inbox;
 > +	u8 has_outbox;
 > +	u8 out_is_imm;
 > +	int (*verify)(struct mlx4_dev *dev, int slave, struct mlx4_vhcr *vhcr,
 > +					    struct mlx4_cmd_mailbox *inbox);
 > +	int (*wrapper)(struct mlx4_dev *dev, int slave, struct mlx4_vhcr *vhcr,
 > +					     struct mlx4_cmd_mailbox *inbox,
 > +					     struct mlx4_cmd_mailbox *outbox);
 > +} cmd_info[] = {
 > +	{MLX4_CMD_QUERY_FW,        0, 1, 0, NULL, NULL},
 > +	{MLX4_CMD_QUERY_ADAPTER,   0, 1, 0, NULL, NULL},

This big structure would be better with designated initializers.  Also
instead of u8 for the flags bool would be better probably.  Then it
becomes more self documenting, ie

	{ .opcode = MLX4_CMD_QUERY_FW, .has_outbox = true }, ...

 > +struct mlx4_vhcr {
 > +	u64 in_param;
 > +	u64 out_param;
 > +	u32 in_modifier;
 > +	u32 timeout;
 > +	u16 op;
 > +	u16 token;
 > +	u8 op_modifier;
 > +	int errno;
 > +};

trivial but can you use tabs to line up the structure field names the
way the rest of the mlx4 declarations do?

 - R.
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