Re: This is where I'm going with fwcontrol

Dieter wrote:
> While looking at the code and wondering what "adjust_gap_count"
> had to do with cyclemaster mode, I noticed that -f was setting
> the 2nd argument to
> send_phy_config(int fd, int root_node, int gap_count)
> which is root_node, not gap_count.
>
> I also noticed that send_phy_config() does (root_node & 0x3f),
> so having the range check be 0x3f rather than INT32_MAX
> seems to make sense.
>
>   
Agreed, the root_node should be checked against 0x3f(or a define that is 
assigned the value of 0x3f ... whatever that really is).
> I haven't yet figured out exactly which 7 bits this stuff is
> actually setting.
>
>   
send_phy_config() is causing the /dev/fwX device to generate a PHY 
configuration Packet(IEEE 1394-1995 4.3.4.3)
<snippet from document>
It is possible to optimize Serial Bus performance for particular 
configurations in the following ways:
     a)   Setting the gap_count used by all nodes to a smaller value 
(appropriate to the actual worst-case number of
          hops between any two nodes)
     b)   Forcing a particular node to be the root after the next bus 
initialization (for example, in isochronous systems,
          the root shall be cycle-master capable)
Both of these actions shall be done for remote nodes using the PHY 
configuration packet shown in figure 4.20. (For the
local node, the PH_CONT.request service is used) The procedures for 
using this PHY packet are described in clause
7.3.5.2.1.
<end snippet>

So, I think you are correct adjust_gap_count should become set_root_node 
as that is what it does.

A PHY Config packet should look like this:
Message ID  Root ID  R T Gap Count
   00(2 bits)  (5 bits)    1 1    (6 bits)
 
So the Root ID(-f in fwcontrol) can't be set to a value greater than 
0x3f(63) and the Gap Count can't be greater than 0x7f(127).  An "R" 
value of 1 means that this is a message to set the root ID.  An "T" 
value of 1 means that this is a message to set the gap count for all 
nodes.  If "R" and "T" are both 0, then the message is ignored.



> So does the following look like an improvement (however minor)
> to anyone else, or just me?  :-)
>
>
> @@ -730,7 +730,7 @@
>         bool dump_phy_reg = false;
>  
>         int32_t priority_budget = -1;
> -       int32_t adjust_gap_count = -1;
> +       int32_t set_root_node = -1;
>         int32_t reset_gap_count = -1;
>         int32_t send_link_on = -1;
>         int32_t send_reset_start = -1;
> @@ -790,9 +790,9 @@
>                         display_board_only = false;
>                         break;
>                 case 'f':
> -                       adjust_gap_count = strtol(optarg, NULL, 0);
> -                       if ( (adjust_gap_count < 0) || (adjust_gap_count > INT32_MAX) )
> -                               err(EX_USAGE, "%s:adjust_gap_count out of range", __func__);
> +                       set_root_node = strtol(optarg, NULL, 0);
> +                       if ( (set_root_node < 0) || (set_root_node > 0x3f) )
> +                               err(EX_USAGE, "%s:set_root_node out of range", __func__);
>                         open_needed = true;
>                         command_set = true;
>                         display_board_only = false;
> @@ -961,8 +961,8 @@
>         /*
>          * Adjust the gap count for this card/bus to value "-f"
>          */
> -       if (adjust_gap_count >= 0)
> -               send_phy_config(fd, adjust_gap_count, -1);
> +       if (set_root_node >= 0)
> +               send_phy_config(fd, set_root_node, -1);
>  
>         /*
>          * Reset the gap count for this card/bus  "-g"
>   
I will chew on and implement this patch tomorrow I think.  It makes 
sense to me, it's just the code in send_phy_config() that is distracting.

I hope this clarifies what this crap means!  :)

-- 
Sean Bruno
MiraLink Corporation
6015 NE 80th Ave, Ste 100
Portland, OR 97218
Phone 503-621-5143
Fax 503-621-5199
MSN: [email protected]
Google:  [email protected]
Yahoo:  [email protected]

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