Ah, ok, I thought your host was a 0.96 host. I see that the xHCI driver does handle the TD size field differently, based on whether the host is a 1.0 host or not (see xhci_td_remainder and xhci_v1_0_td_remainder). I'll have to take a look at that code again to see if it's compliant with the xHCI 1.0 spec. Sarah Sharp In-Reply-To: <CAEro0YF+Ard65B7cysAcaicB4PaSEWkerevwTHXjJx1OvmtDUA@xxxxxxxxxxxxxx> On Fri, Oct 19, 2012 at 11:29:44AM +0530, Chintan Mehta wrote: > Hi Sarah, > > Thanks for the reply. > > Regarding section 4.11.2.4: > TD size is the number of bytes remaining, right shifted by 10. > This is as per the spec version 0.96 > As per spec 1.0 (which I believe is the latest one): > TD Size calculation is having two major changes - > 1. TDSize shows the remaining transfer size for TD including current TRB. > 2. TDSize calculation requires ROUNDUP( TD Transfer Size / Max Packet Size > ). > > Also it states that, > The value of the TD Size in the last Transfer TRB of a TD (TD Size (x)) > shall be cleared to '0' to > explicitly indicate that it is the last Transfer TRB of the TD. > > It seems like driver is still calculating TDSize as per old spec. > > Can you please, share your view on this? > > Thanks, > Chintan > > > On Fri, Oct 19, 2012 at 3:24 AM, Sarah Sharp > <sarah.a.sharp@xxxxxxxxxxxxxxx>wrote: > > > Since you both seem to be asking the same question: > > > > On Wed, Oct 17, 2012 at 10:34:39AM +0530, ankit patel wrote: > > > Thanks Sarah, > > > I just need to know that driver is doing reset when device is not > > > attached by writing HCRST to 1 in USB Command Register of xHC. Does > > > the host controller needs to propagate HOT/WARM reset to USB3 layer when > > > device is not attached ? If yes then when should we consider it to be > > > complete? > > > > Steve McGowan, the xHCI spec architect, is on sabbatical. He'll be back > > on Oct 30, and I'm sure he'll answer your questions then. > > > > Until that point, I suggest you fix your host controller bug for when > > the host gives a TRB pointer for the TRB *after* the TD that finished. > > > > On Wed, Oct 17, 2012 at 03:06:48PM +0530, Chintan Mehta wrote: > > > Hi Sarah, > > > > > > I have got your mail ID from http://gmane.org during my search regarding > > > USB3 xHCI Driver. > > > > > > We have some doubts about xHCI Host Spec. > > > > > > We tried to contact on xhcisupport@xxxxxxxxx, but we have not received > > any > > > reply yet. > > > > > > Can you please, help us to resolve our queries? > > > > > > One more question: > > > xHCI Driver seems to be doing HCRST on startup. > > > If device is not connected, xHCI should propagate Hot/Warm reset to USB3 > > > layer? > > > > I don't know. Ask Steve. More comments below. > > > > > On Fri, Sep 28, 2012 at 4:49 PM, Chintan Mehta < > > > chintan.mehta@xxxxxxxxxxxxxxxx> wrote: > > > > > > > Hi, > > > > > > > > We have some queries regarding TDSize in different TRBs. > > > > > > > > 1. In setup-data-status control transfer case: > > > > > > > > - Device is informed about the transfer length of data stage through > > > > wLength filed in setup stage. > > > > You should not rely on the transfer length in the setup stage. Section > > 4.11.2.2 says, "Note: Some (non-compliant) USB devices use the SETUP > > Data wLength field as a custom parameter for non-data control transfers. > > xHCI implementations should not tie a non-zero wLength value to the > > existence of a Data Stage TD in a control transfer to ensure > > compatibility with those devices." > > > > Don't use the setup stage. Instead, fetch the first data stage TRB, and > > use the TD size field. > > > > > > - Now, data stage may contain data stage trb followed by chained > > > > normal trbs to complete the data stage transfer. > > > > - Question is as below: > > > > - *Chained normal TRB should be placed only when the total data > > > > transfer is more than maxpacket size or data transfer can be > > broken into > > > > different TRBs?* > > > > Data transfers can be broken down into any number of TRBs. There is no > > requirement that they are broken into maxpacket sized chunks. Each TRB > > could have more or less bytes than maxpacket size. Your host will have > > to deal with both. > > > > > > - *If chained normal TRB can be placed without considering the > > > > maxpacket size rule, what should be the value of TDSize in data > > stage TRB? > > > > The number of bytes remaining in the TD, *including* this TRB. So > > TDSize will decrease on each TRB in the TD. (Or stay the same for > > several TDs, if this TD is bigger than what can be represented in the TD > > size field). > > > > > > * > > > > - To elaborate above question, If 9 Bytes are requested in setup > > > > stage. Driver may either put data stage trb with TRB transfer > > length 9 > > > > Bytes or may put a chained normal trb after data stage trb. > > > > Don't rely on the setup stage wLength. > > > > > > - Lets say driver is breaking transfer in two stages and puts data > > > > stage trb with TRB transfer length 8 Bytes, chain bit 1 and TDSize > > 0 - > > > > followed by Normal trb with TRB transfer size 1 Byte, Chain bit 0 > > and > > > > TDSize 0. > > > > - *Is this breaking is proper/valid from driver side?* > > > > See section 4.11.2.4. TD size is the number of bytes remaining, right > > shifted by 10. (8 >> 10) = 0. (1 >> 10) = 0. The TD size is just an > > estimation of the number of bytes remaining. You'll have to look at the > > chain bit to know whether you need to fetch more data for this TD. > > > > > > 2. For Bulk Endpoint: > > > > > > > > - *Driver can put a TD with total TD transfer size less than > > maxpacket > > > > size and more than 1 TRB?* > > > > - For example, Maxpacketsize is 1K. And TD contains 3 TRBs as below: > > > > - 1st trb with TRB transfer length 600 Bytes, chain bit 1 and > > > > TDSize 0 > > > > - 2nd trb with TRB transfer length 200 Bytes, chain bit 1 and > > > > TDSize 0 > > > > - 3rd trb with TRB transfer length 100 Bytes, chain bit 0 and > > > > TDSize 0 > > > > - *What should be the value of TDSize in above TRBs of TD?* > > > > Again, see section 4.11.2.4. > > > > TRB 1 600 (600 + 200 + 100) >> 10 = 0 > > TRB 2 200 (200 + 100) >> 10 = 0 > > TRB 3 100 (100) >> 10 = 0 > > > > Let me know if Steve disagrees. The xHCI driver works with many other > > host controllers, and that's how it implements TD size. > > > > Sarah Sharp > > -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
