Hi Peppe,
Às 8:10 AM de 6/9/2017, Giuseppe CAVALLARO escreveu:
> Hi Joao
>
> On 6/8/2017 8:02 PM, Joao Pinto wrote:
>> This patch fixes the description of the DT AVB parameters and gives
>> an accurate example. It was also included the base values that were
>> used to get the example' CBS paremeter values.
>>
>> Signed-off-by: Joao Pinto <jpi...@synopsys.com>
>> ---
>> Documentation/devicetree/bindings/net/stmmac.txt | 24
>> ++++++++++++++++--------
>> 1 file changed, 16 insertions(+), 8 deletions(-)
>>
>> diff --git a/Documentation/devicetree/bindings/net/stmmac.txt
>> b/Documentation/devicetree/bindings/net/stmmac.txt
>> index c3a7be6..707426d 100644
>> --- a/Documentation/devicetree/bindings/net/stmmac.txt
>> +++ b/Documentation/devicetree/bindings/net/stmmac.txt
>> @@ -109,10 +109,10 @@ Optional properties:
>> [Attention] Queue 0 is reserved for legacy traffic
>> and so no AVB is available in this queue.
>> - Configure Credit Base Shaper (if AVB Mode selected):
>> - - snps,send_slope: enable Low Power Interface
>> - - snps,idle_slope: unlock on WoL
>> - - snps,high_credit: max write outstanding req. limit
>> - - snps,low_credit: max read outstanding req. limit
>> + - snps,send_slope: Send Slope Credit value
>> + - snps,idle_slope: Idle Slope Credit value
>> + - snps,high_credit: High Credit value
>> + - snps,low_credit: Low Credit value
>> - snps,priority: TX queue priority (Range: 0x0 to 0xF)
>> Examples:
>> @@ -143,10 +143,18 @@ Examples:
>> queue1 {
>> snps,avb-algorithm;
>> - snps,send_slope = <0x1000>;
>> - snps,idle_slope = <0x1000>;
>> - snps,high_credit = <0x3E800>;
>> - snps,low_credit = <0xFFC18000>;
>> + /*
>> + * Example AVB parameters based on:
>> + * Allocated Bandwidth: 40%
>> + * Maximum Frame size: 1000 bytes
>> + * Maximum Interference size: 1500 bytes
>> + * Port Transmit Rate: 8
>> + * Scaling Factor: 1024
>> + */
>> + snps,idle_slope = <0xCCC>;
>> + snps,send_slope = <0x1333>;
>> + snps,high_credit = <0x4B0000>;
>
> Thanks for having taken care about this changes, please, as required, add a
> cover-letter
> and give more information about these values that can be tuned by user and,
> for
> example,
> the snps,high_credit could be as default = 0xbe4000 that is a reasonable value
> because
> comes from 1522 * 8 * 1024 and LOW credit is the two complement.
> ^^^^^
> frame size ---> maximum is 16
I calculate the hi credit this way:
HiCredit = BW / 100 * MaxInterferenceSize * 8 * Scaling
Can I assume that you are considering 100% bandwidth for this example channel?
If so, it is not correct, since the maximum bandwidth should be 75%, leaving at
least 25% for default channel 0 (I think this is assured in the hardware).
Thanks,
Joao
>
> Regards
> Peppe
>
>> + snps,low_credit = <0xFFB50000>;
>> snps,priority = <0x1>;
>> };
>> };
>
>
