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. > >> 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. 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. > > 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
