Re: [PATCH for-next 2/2] RDMA/hns: Fix alignment problem of the doorbell

["Liuyixian (Eason)" <liuyixian-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>]

On 2017/12/28 1:40, Ruhl, Michael J wrote:
>> -----Original Message-----
>> From: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org [mailto:linux-rdma-
>> owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org] On Behalf Of Yixian Liu
>> Sent: Monday, December 25, 2017 8:37 AM
>> To: jgg-uk2M96/98Pc@public.gmane.org; leon-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org
>> Cc: dledford-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org; linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
>> Subject: [PATCH for-next 2/2] RDMA/hns: Fix alignment problem of the
>> doorbell
>>
>> The array defined for doorbell is not guaranteed to be 64 bit
>> aligned while we write it to the hardware with 64 bit
>> alignment required.
>>
>> This patch fixes this problem by defining a union for doorbell
>> to make sure it 64 bit alignment.
>>
>> Signed-off-by: Yixian Liu <liuyixian-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
>> Signed-off-by: Lijun Ou <oulijun-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
>> Signed-off-by: Wei Hu (Xavier) <xavier.huwei-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
>> ---
>>  drivers/infiniband/hw/hns/hns_roce_device.h |  5 +++++
>>  drivers/infiniband/hw/hns/hns_roce_hw_v2.c  | 16 ++++++++--------
>>  2 files changed, 13 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/infiniband/hw/hns/hns_roce_device.h
>> b/drivers/infiniband/hw/hns/hns_roce_device.h
>> index dde5178..defc4ee 100644
>> --- a/drivers/infiniband/hw/hns/hns_roce_device.h
>> +++ b/drivers/infiniband/hw/hns/hns_roce_device.h
>> @@ -569,6 +569,11 @@ struct hns_roce_eq_table {
>>  	void __iomem		**eqc_base; /* only for hw v1 */
>>  };
>>
>> +union hns_roce_db {
>> +	u64	doorbell64;
> 
> Are there any concerns with big endian/little ending for this value?
> 
> Mike
> 

I will consider this issue in patch v3, Mike, thank you!

>> +	u32	doorbell[2];
>> +};
>> +
>>  struct hns_roce_caps {
>>  	u8		num_ports;
>>  	int		gid_table_len[HNS_ROCE_MAX_PORTS];
>> diff --git a/drivers/infiniband/hw/hns/hns_roce_hw_v2.c
>> b/drivers/infiniband/hw/hns/hns_roce_hw_v2.c
>> index 7f393f6..ee26bbd 100644
>> --- a/drivers/infiniband/hw/hns/hns_roce_hw_v2.c
>> +++ b/drivers/infiniband/hw/hns/hns_roce_hw_v2.c
>> @@ -3172,33 +3172,33 @@ static int hns_roce_v2_modify_cq(struct ib_cq
>> *cq, u16 cq_count, u16 cq_period)
>>
>>  static void set_eq_cons_index_v2(struct hns_roce_eq *eq)
>>  {
>> -	u32 doorbell[2];
>> +	union hns_roce_db db;
>>
>> -	doorbell[0] = 0;
>> -	doorbell[1] = 0;
>> +	db.doorbell[0] = 0;
>> +	db.doorbell[1] = 0;
>>
>>  	if (eq->type_flag == HNS_ROCE_AEQ) {
>> -		roce_set_field(doorbell[0], HNS_ROCE_V2_EQ_DB_CMD_M,
>> +		roce_set_field(db.doorbell[0],
>> HNS_ROCE_V2_EQ_DB_CMD_M,
>>  			       HNS_ROCE_V2_EQ_DB_CMD_S,
>>  			       eq->arm_st ==
>> HNS_ROCE_V2_EQ_ALWAYS_ARMED ?
>>  			       HNS_ROCE_EQ_DB_CMD_AEQ :
>>  			       HNS_ROCE_EQ_DB_CMD_AEQ_ARMED);
>>  	} else {
>> -		roce_set_field(doorbell[0], HNS_ROCE_V2_EQ_DB_TAG_M,
>> +		roce_set_field(db.doorbell[0],
>> HNS_ROCE_V2_EQ_DB_TAG_M,
>>  			       HNS_ROCE_V2_EQ_DB_TAG_S, eq->eqn);
>>
>> -		roce_set_field(doorbell[0], HNS_ROCE_V2_EQ_DB_CMD_M,
>> +		roce_set_field(db.doorbell[0],
>> HNS_ROCE_V2_EQ_DB_CMD_M,
>>  			       HNS_ROCE_V2_EQ_DB_CMD_S,
>>  			       eq->arm_st ==
>> HNS_ROCE_V2_EQ_ALWAYS_ARMED ?
>>  			       HNS_ROCE_EQ_DB_CMD_CEQ :
>>  			       HNS_ROCE_EQ_DB_CMD_CEQ_ARMED);
>>  	}
>>
>> -	roce_set_field(doorbell[1], HNS_ROCE_V2_EQ_DB_PARA_M,
>> +	roce_set_field(db.doorbell[1], HNS_ROCE_V2_EQ_DB_PARA_M,
>>  		       HNS_ROCE_V2_EQ_DB_PARA_S,
>>  		       (eq->cons_index & HNS_ROCE_V2_CONS_IDX_M));
>>
>> -	hns_roce_write64_k(doorbell, eq->doorbell);
>> +	hns_roce_write64_k(db.doorbell, eq->doorbell);
>>
>>  	/* Make sure we update the consumer index of EQ before
>>  	 * accessing it later
>> --
>> 1.9.1
>>
>> --
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> 
> .
> 

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