[T10] Question about NCQ H2D transmission be postponed when receive X_RDY

Ralph Weber roweber at ieee.org
Fri Sep 30 12:15:58 PDT 2016

Dear Sir:

I doubt whether any of the SCSI experts who participate in this 
reflector would feel comfortable using this venue to comment upon the 
operation of another organization's specification.

Please consider posting this question to:

t13 at t13.org -- the T13 Technical Committee (ATA & ATAPI) reflector

or possibly

http://www.sata-io.org/contacts -- the SATA IO contact-us page

All the best,


On 9/30/2016 6:05 AM, Guojian (F) wrote:
> *发件人:*aidepei
> *发送时间:*2016年9月30日16:18
> *收件人:*Guojian (F)
> *主题:*Question about NCQ H2D transmission be postponed when receive X_RDY
> Hi,
> I have confusion about NCQ H2D tansmission.
> According to SATA spec 3.2(9.6.3 Link transmit state machine)
> LT1: HL_SendChkRdy state, this state is entered if a frame 
> transmission has been requested by the host Transport layer.
> If in this state, the Link layer transmits X_RDYp and waits for X_RDYp 
> or R_RDYp  from the Phy layer.
> NOTE 43 - It is possible that both the host and the device 
> simultaneously request frame transmission by transmitting X_RDYp . If 
> the host receives X_RDYp
> while transmitting X_RDYp , the host shall back off and enter the L_R 
> cvWaitFifo state, _postponing its desired frame transmission until the 
> device has completed its frame transmission and the bus is_
> _idle. _
> Transition LT1:1, if the host Link layer receives R_RDYp from the Phy 
> layer, the Link layer shall make a transition to the LT3: L_SendSOF 
> state.
> Transition LT1:2, if the host Link layer receives X_RDYp  from the Phy 
> layer, the Link layer shall make a transition to the LR 2: 
> L_RcvWaitFifo state.
> Consider following scenario:
> host adapter is sending X_RDYp for H2D(NCQ command) but receive X_RDYp 
> for DMA SETUP FIS. After complete reception of DMA SETUP FIS, link 
> layer retransmits H2D(NCQ command), it will result in SATA device 
> aborting the command(NCQ data phase interrupted by H2D).
> My question is :
> In this scenario,
> 1)the H2D(NCQ command) should be postponed in link layer until the 
> device completed its frame transmission or
> 2)link layer should reports error to transport layer because  X_RDY 
> conflicts
> which one is correct?
> Thanks for your help.
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