[Skiboot] [PATCH 2/2] npu2-hw-procedures.c: Correct phy lane mapping

[Andrew Donnellan]

On 25/01/18 04:18, Frederic Barrat wrote:
> 
> 
> Le 24/01/2018 à 04:44, Alistair Popple a écrit :
>> Each nvlink device is associated with a particular group of OBUS lanes 
>> via
>> a lane mask which is read from HDAT via the device-tree. However 
>> Skiboot's
>> interpretation of lane mask was different to what is exported from the
>> HDAT.
>>
>> Specifically the lane mask bits in the HDAT are encoded in IBM bit 
>> ordering
>> for a 24-bit wide value. So for example in normal bit ordering lane-0 is
>> represented by having lane-mask bit 23 set and lane-23 is represented by
>> lane-mask bit 0. This patch alters the Skiboot interpretation to match 
>> what
>> is passed from HDAT.
>>
>> Signed-off-by: Alistair Popple <alistair at popple.id.au>
>> ---
> 
> Thanks for the heads up!
> 
> Reviewed-by: Frederic Barrat <fbarrat at linux.vnet.ibm.com>
> 
> Andrew: please confirm you're seeing this. It obviously will have an 
> impact when you merge it with your patchset (and I can see troubles 
> ahead for our custom device tree on ZZ).

Reviewed-by: Andrew Donnellan <andrew.donnellan at au1.ibm.com>

I'll apply this on my opencapi branch and fix things up accordingly.

> 
>    Fred
> 
>>   hw/npu2-hw-procedures.c | 6 +++---
>>   1 file changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/hw/npu2-hw-procedures.c b/hw/npu2-hw-procedures.c
>> index a43952d7..b21c399d 100644
>> --- a/hw/npu2-hw-procedures.c
>> +++ b/hw/npu2-hw-procedures.c
>> @@ -102,12 +102,12 @@ struct npu2_phy_reg 
>> NPU2_PHY_RX_CTL_DATASM_CLKDIST_PDWN = {0x2e0, 60, 1};
>>   #define NPU2_PHY_REG(scom_base, reg, lane)                    \
>>       SETFIELD(PPC_BITMASK(27, 31), ((reg)->offset << 42) | scom_base, 
>> lane)
>>
>> -#define NPU2_MAX_PHY_LANES            24
>> +#define NPU2_MAX_PHY_LANE            23
>>
>>   /* This is a bit of a gross hack but it does the job */
>>   #define FOR_EACH_LANE(ndev, lane) \
>> -    for (lane = 0; lane < NPU2_MAX_PHY_LANES; lane++)    \
>> -        if (!(ndev->lane_mask & (1 << lane)))        \
>> +    for (lane = 0; lane <= NPU2_MAX_PHY_LANE; lane++)    \
>> +        if (!(ndev->lane_mask & (1 << (NPU2_MAX_PHY_LANE - lane)))) \
>>               continue;                \
>>           else
>>

-- 
Andrew Donnellan              OzLabs, ADL Canberra
andrew.donnellan at au1.ibm.com  IBM Australia Limited