Hi, Jerry Huang <jerry.huang@xxxxxxx> writes: > Hi, Balbi, >> -----Original Message----- >> From: Felipe Balbi [mailto:balbi@xxxxxxxxxx] >> Sent: Friday, December 16, 2016 7:44 PM >> To: Jerry Huang <jerry.huang@xxxxxxx>; gregkh@xxxxxxxxxxxxxxxxxxx >> Cc: linux-usb@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Rajesh Bhagat >> <rajesh.bhagat@xxxxxxx> >> Subject: RE: [PATCH] USB3/DWC3: Enable undefined length INCR burst type >> >> >> Hi, >> >> Jerry Huang <jerry.huang@xxxxxxx> writes: >> >> there's no need for that. This patch is in good format. I do have a >> >> question, >> >> however: how do you know this will work for all users? Burst size is >> >> a function of how wide the interconnect where dwc3 is attached to, is. >> > So I need to generate one new property in usb node to identify my >> platform? >> >> Well, we probably need a property to be passed, yes. But let's go through it >> all first :-) > > I think "snps,quirk-frame-length-adjustment" is one good reference, > which can pass the required value to driver from DTS file. that's not for burst increment, though. >> >> You could very well be degrading performance for some users here. Can >> >> you send me the result of the following commands *without* this patch >> applied? >> >> >> >> # mkdir -p /d >> >> # mount -t debugfs none /d >> >> # cat /d/*dwc3*/regdump >> >> >> > Below is the regdump: >> > root@ls1043ardb:/d/3000000.usb3# cat regdump >> > GSBUSCFG0 = 0x00100080 >> >> so you already have INCR256 here. There's one note in the databook which >> just caught my attention. It states the following: >> >> "Undefined burst length has priority over all other burst lenghts." >> >> This means that setting both INCR16 and undefined INCR is unnecessary. > When bit0 = 1 (Undefined Length INCR Burst Type Enable), which means: > 1: INCR (undefined length) burst mode > - AHB configurations: HBURST uses SINGLE or INCR > of any length less than or equal to the largest-enabled > burst length of INCR4/8/16/32/64/128/256. > - AXI configurations: ARLEN/AWLEN uses any length > less than or equal to the largest-enabled burst length > of INCR4/8/16/32/64/128/256. interesting, it doesn't describe what happens to OCP or PCI. > So, after enable undefined length INCR burst and enable INCR16, > controller will use less than or equal to 16byte. > >> Only Undefined INCR will be taken into consideration. Can you check with >> your HW engineers what's the largest burst the interconnect is supposed to >> support? > I will check it with IP designer. cool, thanks :-) >> > GSBUSCFG1 = 0x00000700 >> >> 8 AXI pipelined requests >> >> > GSNPSID = 0x5533280a >> >> 2.80a cool :-) >> >> I'll check these settings on my platform as well and see if there's any setting >> which would improve transfer speed. This is a very good idea, btw, but we >> need to be careful about how to play with it. >> >> -- >> balbi > -- > 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 -- balbi -- 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
