Re: [PATCH 04/15] net: hbl_cn: QP state machine

[Omer Shpigelman]

On 6/18/24 12:00, Leon Romanovsky wrote:
> On Tue, Jun 18, 2024 at 07:58:55AM +0000, Omer Shpigelman wrote:
>> On 6/18/24 10:08, Leon Romanovsky wrote:
>>> On Tue, Jun 18, 2024 at 05:50:15AM +0000, Omer Shpigelman wrote:
>>>> On 6/17/24 16:18, Leon Romanovsky wrote:
>>>>> [Some people who received this message don't often get email from leon@xxxxxxxxxx. Learn why this is important at https://aka.ms/LearnAboutSenderIdentification ]
>>>>>
>>>>> On Thu, Jun 13, 2024 at 11:21:57AM +0300, Omer Shpigelman wrote:
>>>>>> Add a common QP state machine which handles the moving for a QP from one
>>>>>> state to another including performing necessary checks, draining
>>>>>> in-flight transactions, invalidating caches and error reporting.
>>>>>>
>>>>>> Signed-off-by: Omer Shpigelman <oshpigelman@xxxxxxxxx>
>>>>>> Co-developed-by: Abhilash K V <kvabhilash@xxxxxxxxx>
>>>>>> Signed-off-by: Abhilash K V <kvabhilash@xxxxxxxxx>
>>>>>> Co-developed-by: Andrey Agranovich <aagranovich@xxxxxxxxx>
>>>>>> Signed-off-by: Andrey Agranovich <aagranovich@xxxxxxxxx>
>>>>>> Co-developed-by: Bharat Jauhari <bjauhari@xxxxxxxxx>
>>>>>> Signed-off-by: Bharat Jauhari <bjauhari@xxxxxxxxx>
>>>>>> Co-developed-by: David Meriin <dmeriin@xxxxxxxxx>
>>>>>> Signed-off-by: David Meriin <dmeriin@xxxxxxxxx>
>>>>>> Co-developed-by: Sagiv Ozeri <sozeri@xxxxxxxxx>
>>>>>> Signed-off-by: Sagiv Ozeri <sozeri@xxxxxxxxx>
>>>>>> Co-developed-by: Zvika Yehudai <zyehudai@xxxxxxxxx>
>>>>>> Signed-off-by: Zvika Yehudai <zyehudai@xxxxxxxxx>
>>>>>> ---
>>>>>>  .../ethernet/intel/hbl_cn/common/hbl_cn_qp.c  | 480 +++++++++++++++++-
>>>>>>  1 file changed, 479 insertions(+), 1 deletion(-)
>>>>>>
>>>>>> diff --git a/drivers/net/ethernet/intel/hbl_cn/common/hbl_cn_qp.c b/drivers/net/ethernet/intel/hbl_cn/common/hbl_cn_qp.c
>>>>>> index 9ddc23bf8194..26ebdf448193 100644
>>>>>> --- a/drivers/net/ethernet/intel/hbl_cn/common/hbl_cn_qp.c
>>>>>> +++ b/drivers/net/ethernet/intel/hbl_cn/common/hbl_cn_qp.c
>>>>>> @@ -6,8 +6,486 @@
>>>>>
>>>>> <...>
>>>>>
>>>>>> +/* The following table represents the (valid) operations that can be performed on
>>>>>> + * a QP in order to move it from one state to another
>>>>>> + * For example: a QP in RTR state can be moved to RTS state using the CN_QP_OP_RTR_2RTS
>>>>>> + * operation.
>>>>>> + */
>>>>>> +static const enum hbl_cn_qp_state_op qp_valid_state_op[CN_QP_NUM_STATE][CN_QP_NUM_STATE] = {
>>>>>> +     [CN_QP_STATE_RESET] = {
>>>>>> +             [CN_QP_STATE_RESET]     = CN_QP_OP_2RESET,
>>>>>> +             [CN_QP_STATE_INIT]      = CN_QP_OP_RST_2INIT,
>>>>>> +             [CN_QP_STATE_SQD]       = CN_QP_OP_NOP,
>>>>>> +             [CN_QP_STATE_QPD]       = CN_QP_OP_NOP,
>>>>>> +     },
>>>>>> +     [CN_QP_STATE_INIT] = {
>>>>>> +             [CN_QP_STATE_RESET]     = CN_QP_OP_2RESET,
>>>>>> +             [CN_QP_STATE_ERR]       = CN_QP_OP_2ERR,
>>>>>> +             [CN_QP_STATE_INIT]      = CN_QP_OP_NOP,
>>>>>> +             [CN_QP_STATE_RTR]       = CN_QP_OP_INIT_2RTR,
>>>>>> +             [CN_QP_STATE_SQD]       = CN_QP_OP_NOP,
>>>>>> +             [CN_QP_STATE_QPD]       = CN_QP_OP_NOP,
>>>>>> +     },
>>>>>> +     [CN_QP_STATE_RTR] = {
>>>>>> +             [CN_QP_STATE_RESET]     = CN_QP_OP_2RESET,
>>>>>> +             [CN_QP_STATE_ERR]       = CN_QP_OP_2ERR,
>>>>>> +             [CN_QP_STATE_RTR]       = CN_QP_OP_RTR_2RTR,
>>>>>> +             [CN_QP_STATE_RTS]       = CN_QP_OP_RTR_2RTS,
>>>>>> +             [CN_QP_STATE_SQD]       = CN_QP_OP_NOP,
>>>>>> +             [CN_QP_STATE_QPD]       = CN_QP_OP_RTR_2QPD,
>>>>>> +     },
>>>>>> +     [CN_QP_STATE_RTS] = {
>>>>>> +             [CN_QP_STATE_RESET]     = CN_QP_OP_2RESET,
>>>>>> +             [CN_QP_STATE_ERR]       = CN_QP_OP_2ERR,
>>>>>> +             [CN_QP_STATE_RTS]       = CN_QP_OP_RTS_2RTS,
>>>>>> +             [CN_QP_STATE_SQD]       = CN_QP_OP_RTS_2SQD,
>>>>>> +             [CN_QP_STATE_QPD]       = CN_QP_OP_RTS_2QPD,
>>>>>> +             [CN_QP_STATE_SQERR]     = CN_QP_OP_RTS_2SQERR,
>>>>>> +     },
>>>>>> +     [CN_QP_STATE_SQD] = {
>>>>>> +             [CN_QP_STATE_RESET]     = CN_QP_OP_2RESET,
>>>>>> +             [CN_QP_STATE_ERR]       = CN_QP_OP_2ERR,
>>>>>> +             [CN_QP_STATE_SQD]       = CN_QP_OP_SQD_2SQD,
>>>>>> +             [CN_QP_STATE_RTS]       = CN_QP_OP_SQD_2RTS,
>>>>>> +             [CN_QP_STATE_QPD]       = CN_QP_OP_SQD_2QPD,
>>>>>> +             [CN_QP_STATE_SQERR]     = CN_QP_OP_SQD_2SQ_ERR,
>>>>>> +     },
>>>>>> +     [CN_QP_STATE_QPD] = {
>>>>>> +             [CN_QP_STATE_RESET]     = CN_QP_OP_2RESET,
>>>>>> +             [CN_QP_STATE_ERR]       = CN_QP_OP_2ERR,
>>>>>> +             [CN_QP_STATE_SQD]       = CN_QP_OP_NOP,
>>>>>> +             [CN_QP_STATE_QPD]       = CN_QP_OP_NOP,
>>>>>> +             [CN_QP_STATE_RTR]       = CN_QP_OP_QPD_2RTR,
>>>>>> +     },
>>>>>> +     [CN_QP_STATE_SQERR] = {
>>>>>> +             [CN_QP_STATE_RESET]     = CN_QP_OP_2RESET,
>>>>>> +             [CN_QP_STATE_ERR]       = CN_QP_OP_2ERR,
>>>>>> +             [CN_QP_STATE_SQD]       = CN_QP_OP_SQ_ERR_2SQD,
>>>>>> +             [CN_QP_STATE_SQERR]     = CN_QP_OP_NOP,
>>>>>> +     },
>>>>>> +     [CN_QP_STATE_ERR] = {
>>>>>> +             [CN_QP_STATE_RESET]     = CN_QP_OP_2RESET,
>>>>>> +             [CN_QP_STATE_ERR]       = CN_QP_OP_2ERR,
>>>>>> +     }
>>>>>> +};
>>>>>
>>>>> I don't understand why IBTA QP state machine is declared in ETH driver
>>>>> and not in IB driver.
>>>>>
>>>>
>>>> Implementing the actual transitions between the states requires full
>>>> knowledge of the HW e.g. when to flush, cache invalidation, timeouts.
>>>> Our IB driver is agnostic to the ASIC type by design. Note that more ASIC
>>>> generations are planned to be added and the IB driver should not be aware
>>>> of these additional HWs.
>>>> Hence we implemeted the QP state machine in the CN driver which is aware
>>>> of the actual HW.
>>>
>>> Somehow ALL other IB drivers are able to implement this logic in the IB,
>>> while supporting multiple ASICs. I don't see a reason why you can't do
>>> the same.
>>>
>>
>> If we are referring to this actual table, then I can move it to the IB
>> driver and the CN driver will fetch the needed opcode via a function
>> pointer.
>> Is that ok?
> 
> This table spotted my attention, but right separation shouldn't be limited
> to only this table. The outcome of this conversation should be:
> "IB specific logic should be in IB driver, and CN driver should be able to
> handle only low-level operations".
> 
> Thanks

Ok, I'll check how we can move the IB specific logic to the IB driver.