> On Fri, 2009-06-12 at 07:05 -0700, Jean-Louis Dupond wrote:
>> Hello,
>>
>> I'm experiencing a problem with my "Broadcom Corporation NetXtreme
>> BCM5722 Gigabit Ethernet PCI Express" network card in my Dell R300
>> servers. When booting the server, the network card sometimes doesn't
>> advertise gigabit speeds, and so it auto-negotiates @ 10mbit. The speed
>> can then be set to gigabit with mii-tool, but its not a good solution!
>> On the other hand, sometimes when it boots, it just works perfectly, and
>> advertises gigabit speeds & auto-negotiates on gigabit!
>>
>> I tried to debug the driver a bit, and found some strange behavior
>> :) Only 2 values were different in the writephy function when it booted
>> @ 10mbit & gigabit.
>>
>> I found something obvious in the tg3_readphy & tg3_writephy methods.
>>
>>> 807 while (loops != 0) {
>>> 808 udelay(10);
>>> 809 frame_val = tr32(MAC_MI_COM);
>>> 810 if ((frame_val & MI_COM_BUSY) == 0) {
>>> 811 udelay(5);
>>> 812 frame_val = tr32(MAC_MI_COM);
>>> 813 break;
>>> 814 }
>>> 815 loops -= 1;
>>> 816 }
>
> This code was written like this to make sure we get the correct MDIO
> data. The data is supposed to be valid when the MI_COM_BUSY bit is
> cleared. But on some chips, the data may not be ready until some
> microseconds after the BUSY bit is cleared.
>
> When you see the "wrong" speed being established, please provide the mii
> register dump using mii-tool -vvv eth0. We'll then be able to see what
> we advertised and what the other side advertised.
>
> Thanks.
>
>> On line 809 frame_val is filled with a read (tr32) from the device.
>> On line 810 we check if its not 'MI_COM_BUSY'
>> If not then we have a delay of 5, and then we read it again ?!
>> I don't know why the value is read twice! I checked with some other
>> drivers (also broadcom) and there the read command was given some other
>> argument when reading the BUSY state, and then in the if, it was really
>> fetching the data. But in this case, we only have 2 times the same
>> argument!
>>
>> With the original code the server booted into 10mbit the half of the
>> boots! When I removed line 811 & 812, then it booted into 10mbit only
>> 1/20 times ! Which is way better ! But its still not fully fixed!
>>
>> ---------------------------------------------------------------------------
>>
>> Today I found the programmers documentation on the Broadcom website and it
>> mentions the following:
>>
>>> // Write value to MI communication register
>>> Mi_Communication_Register = Value32
>>> // Now read back MI Communication register until the start bit
>>> // has been cleared or we have timed out (>5000 reads)
>>> Loopcount = 5000
>>> While (LoopCount > 0)
>>> Begin
>>> Value32 = Mi_Communication_Register
>>> If (!(Value32 | 0x20000000)) then BREAK loop
>>> Else Loopcount--
>>> End
>> Here u can see its NOT needed to read the value twice.
>> Also there is no delay mentioned, so I removed it, and rebooted 20 times
>> without 1 time on 10mbit !
>>
>>
>> Feel free to give any other solutions / comments !
>>
>> Sincerely,
>> Jean-Louis Dupond
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