Hi, Rob, > -----Original Message----- > From: Rob Herring [mailto:r...@kernel.org] > Sent: Wednesday, January 04, 2017 5:24 AM > To: Jerry Huang <jerry.hu...@nxp.com> > Cc: ba...@kernel.org; mark.rutl...@arm.com; catalin.mari...@arm.com; > will.dea...@arm.com; li...@armlinux.org.uk; devicet...@vger.kernel.org; > linux-...@vger.kernel.org; linux-kernel@vger.kernel.org; linux-arm- > ker...@lists.infradead.org > Subject: Re: [PATCH v3 2/3] USB3/DWC3: Add property "snps, incr-burst- > type-adjustment" for INCR burst type > > On Thu, Dec 22, 2016 at 8:52 PM, Jerry Huang <jerry.hu...@nxp.com> wrote: > > Hi, Rob, > >> -----Original Message----- > >> From: Rob Herring [mailto:r...@kernel.org] > >> Sent: Friday, December 23, 2016 2:45 AM > >> To: Jerry Huang <jerry.hu...@nxp.com> > >> Cc: ba...@kernel.org; mark.rutl...@arm.com; catalin.mari...@arm.com; > >> will.dea...@arm.com; li...@armlinux.org.uk; > >> devicet...@vger.kernel.org; linux-...@vger.kernel.org; > >> linux-kernel@vger.kernel.org; linux-arm- ker...@lists.infradead.org > >> Subject: Re: [PATCH v3 2/3] USB3/DWC3: Add property "snps, > >> incr-burst- type-adjustment" for INCR burst type > >> > >> On Mon, Dec 19, 2016 at 05:25:53PM +0800, Changming Huang wrote: > >> > New property "snps,incr-burst-type-adjustment = <x>, <y>" for > >> > USB3.0 > >> DWC3. > >> > Field "x": 1/0 - undefined length INCR burst type enable or not; > >> > Field > >> > "y": INCR4/INCR8/INCR16/INCR32/INCR64/INCR128/INCR256 burst type. > >> > > >> > While enabling undefined length INCR burst type and INCR16 burst > >> > type, get better write performance on NXP Layerscape platform: > >> > around 3% improvement (from 364MB/s to 375MB/s). > >> > > >> > Signed-off-by: Changming Huang <jerry.hu...@nxp.com> > >> > --- > >> > Changes in v3: > >> > - add new property for INCR burst in usb node. > >> > > >> > Documentation/devicetree/bindings/usb/dwc3.txt | 5 +++++ > >> > arch/arm/boot/dts/ls1021a.dtsi | 1 + > >> > arch/arm64/boot/dts/freescale/fsl-ls1043a.dtsi | 3 +++ > >> > arch/arm64/boot/dts/freescale/fsl-ls2080a.dtsi | 2 ++ > >> > 4 files changed, 11 insertions(+) > >> > > >> > diff --git a/Documentation/devicetree/bindings/usb/dwc3.txt > >> > b/Documentation/devicetree/bindings/usb/dwc3.txt > >> > index e3e6983..8c405a3 100644 > >> > --- a/Documentation/devicetree/bindings/usb/dwc3.txt > >> > +++ b/Documentation/devicetree/bindings/usb/dwc3.txt > >> > @@ -55,6 +55,10 @@ Optional properties: > >> > fladj_30mhz_sdbnd signal is invalid or incorrect. > >> > > >> > - <DEPRECATED> tx-fifo-resize: determines if the FIFO *has* to be > >> reallocated. > >> > + - snps,incr-burst-type-adjustment: Value for INCR burst type of > >> GSBUSCFG0 > >> > + register, undefined length INCR burst type enable and INCRx type. > >> > + First field is for undefined length INCR burst type enable or not. > >> > + Second field is for largest INCRx type enabled. > >> > >> Why do you need the first field? Is the 2nd field used if the 1st is 0? > >> If not, then just use the presence of the property to enable or not. > > The first field is one switch. > > When it is 1, means undefined length INCR burst type enabled, we can use > any length less than or equal to the largest-enabled burst length of > INCR4/8/16/32/64/128/256. > > When it is zero, means INCRx burst mode enabled, we can use one fixed > burst length of 1/4/8/16/32/64/128/256 byte. > > So, the 2nd field is used if the 1st is 0, we need to select one largest > > burst > length the USB controller can support. > > If we don't want to change the value of this register (use the default > > value), > we don't need to add this property to usb node. > > Just make this a single value with 0 meaning INCR and 4/8/16/etc being INCRx. Maybe, I didn't describe it clearly. According to DWC3 spec, the value "0" of field INCRBrstEna means INCRx burst mode, 1 means INCR burst mode. Regardless of the value of INCRBrstEna [bit0], we need to modify the other field bit[1,2,3,4,5,6,7] to one INCR burst type for the platform supported. Ad you mentioned, if we just use a single value with 0 meaning INCR and 4/8/16/etc being INCRx. I understand totally that when it is none-zero, we can use it for INCR burst mode. Then, when it is 0, how to select the INCRx value?
So, I think we still need two vaue to specify INCRBrstEna and INCRx burst type.
