Subject: Re: [PATCH]: Third (final?) release of Sun Neptune driver

From: Matheos Worku <[email-masked]>
Date: Fri, 05 Oct 2007 10:45:43 -0700

Ingo Oeser wrote:
> Hi David,
>
> some minor nits.
>
> Could this driver be split into more files. 8k lines per file
> is quite a lot. Although GCC might optimize it best this way :-)
>   

Ingo,

Some r info on  Neptune HW  to explains some of the constants ...
Regards
Matheos

>> +	ctrl_val = (ENET_SERDES_CTRL_SDET_0 |
>> +		    ENET_SERDES_CTRL_SDET_1 |
>> +		    ENET_SERDES_CTRL_SDET_2 |
>> +		    ENET_SERDES_CTRL_SDET_3 |
>> +		    (0x5 << ENET_SERDES_CTRL_EMPH_0_SHIFT) |
>> +		    (0x5 << ENET_SERDES_CTRL_EMPH_1_SHIFT) |
>> +		    (0x5 << ENET_SERDES_CTRL_EMPH_2_SHIFT) |
>> +		    (0x5 << ENET_SERDES_CTRL_EMPH_3_SHIFT) |
>> +		    (0x1 << ENET_SERDES_CTRL_LADJ_0_SHIFT) |
>> +		    (0x1 << ENET_SERDES_CTRL_LADJ_1_SHIFT) |
>> +		    (0x1 << ENET_SERDES_CTRL_LADJ_2_SHIFT) |
>> +		    (0x1 << ENET_SERDES_CTRL_LADJ_3_SHIFT));
>> +	test_cfg_val = 0;
>> +
>> +	if (lp->loopback_mode == LOOPBACK_PHY) {
>> +		test_cfg_val |= ((ENET_TEST_MD_PAD_LOOPBACK <<
>> +				  ENET_SERDES_TEST_MD_0_SHIFT) |
>> +				 (ENET_TEST_MD_PAD_LOOPBACK <<
>> +				  ENET_SERDES_TEST_MD_1_SHIFT) |
>> +				 (ENET_TEST_MD_PAD_LOOPBACK <<
>> +				  ENET_SERDES_TEST_MD_2_SHIFT) |
>> +				 (ENET_TEST_MD_PAD_LOOPBACK <<
>> +				  ENET_SERDES_TEST_MD_3_SHIFT));
>> +	}
>> +
>> +	nw64(ctrl_reg, ctrl_val);
>> +	nw64(test_cfg_reg, test_cfg_val);
>> +
>> +	for (i = 0; i < 4; i++) {
>>     
>
> why 4? (magic number)
>   
The MAC HW has 4 SERDES lanes. Need to configure each lane
>   
>   
>> +static void niu_set_max_burst(struct niu *np, struct tx_ring_info *rp)
>> +{
>> +	int mtu = np->dev->mtu;
>> +
>> +	rp->max_burst = mtu + 32;
>> +	if (rp->max_burst > 4096)
>> +		rp->max_burst = 4096;
>>     
>
> Why 32 and 4096? (Magic values)
>   
These values were recommended by the HW designers for fair utilization 
of DRR  feature among TX/RX rings.
>   
>> +}
>> +
>>     
>
> ... ok, I stop here, since this drivers is damn big :-)
>
> Best Regards
>
> Ingo Oeser
>