Jun Li wrote: > Hi > >> -----Original Message----- >> From: Thinh Nguyen <[email protected]> >> Sent: 2020年5月19日 14:46 >> To: Jun Li <[email protected]>; Felipe Balbi <[email protected]>; Jun Li >> <[email protected]> >> Cc: John Stultz <[email protected]>; lkml >> <[email protected]>; Yu >> Chen <[email protected]>; Greg Kroah-Hartman <[email protected]>; >> Rob >> Herring <[email protected]>; Mark Rutland <[email protected]>; ShuFan Lee >> <[email protected]>; Heikki Krogerus <[email protected]>; >> Suzuki K Poulose <[email protected]>; Chunfeng Yun >> <[email protected]>; Hans de Goede <[email protected]>; Andy >> Shevchenko >> <[email protected]>; Valentin Schneider <[email protected]>; >> Jack Pham <[email protected]>; Linux USB List >> <[email protected]>; open >> list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS >> <[email protected]>; >> Peter Chen <[email protected]> >> Subject: Re: [PATCH v4 3/9] usb: dwc3: Increase timeout for CmdAct cleared >> by device >> controller >> >> Thinh Nguyen wrote: >>> Jun Li wrote: >>>>> -----Original Message----- >>>>> From: Felipe Balbi <[email protected]> On Behalf Of Felipe Balbi >>>>> Sent: 2020年5月16日 19:57 >>>>> To: Jun Li <[email protected]>; Thinh Nguyen >>>>> <[email protected]>; Jun Li <[email protected]> >>>>> Cc: John Stultz <[email protected]>; lkml >>>>> <[email protected]>; Yu Chen <[email protected]>; Greg >>>>> Kroah-Hartman <[email protected]>; Rob Herring >>>>> <[email protected]>; Mark Rutland <[email protected]>; ShuFan >>>>> Lee <[email protected]>; Heikki Krogerus >>>>> <[email protected]>; >>>>> Suzuki K Poulose <[email protected]>; Chunfeng Yun >>>>> <[email protected]>; Hans de Goede <[email protected]>; >>>>> Andy Shevchenko <[email protected]>; Valentin Schneider >>>>> <[email protected]>; Jack Pham <[email protected]>; >>>>> Linux USB List <[email protected]>; open list:OPEN FIRMWARE >>>>> AND FLATTENED DEVICE TREE BINDINGS <[email protected]>; >>>>> Peter Chen <[email protected]>; Thinh Nguyen >>>>> <[email protected]> >>>>> Subject: RE: [PATCH v4 3/9] usb: dwc3: Increase timeout for CmdAct >>>>> cleared by device controller >>>>> >>>>> >>>>> Hi, >>>>> >>>>> Jun Li <[email protected]> writes: >>>>>>>>> Hi Thinh, could you comment this? >>>>>>>> You only need to wake up the usb2 phy when issuing the command >>>>>>>> while running in highspeed or below. If you're running in SS or >>>>>>>> higher, internally the controller does it for you for usb3 phy. >>>>>>>> In Jun's case, it seems like it takes longer for his phy to wake up. >>>>>>>> >>>>>>>> IMO, in this case, I think it's fine to increase the command timeout. >>>>>>> Is there an upper limit to this? Is 32k clock the slowest that can >>>>>>> be fed to the PHY as a suspend clock? >>>>>> Yes, 32K clock is the slowest, Per DWC3 document on Power Down >>>>>> Scale (bits 31:19 of GCTL): >>>>>> >>>>>> "Power Down Scale (PwrDnScale) >>>>>> The USB3 suspend_clk input replaces pipe3_rx_pclk as a clock source >>>>>> to a small part of the USB3 controller that operates when the SS >>>>>> PHY is in its lowest power (P3) state, and therefore does not provide a >>>>>> clock. >>>>>> The Power Down Scale field specifies how many suspend_clk periods >>>>>> fit into a 16 kHz clock period. When performing the division, round >>>>>> up the remainder. >>>>>> For example, when using an 8-bit/16-bit/32-bit PHY and 25-MHz >>>>>> Suspend clock, Power Down Scale = 25000 kHz/16 kHz = 13'd1563 >>>>>> (rounder up) >>>>>> Note: >>>>>> - Minimum Suspend clock frequency is 32 kHz >>>>>> - Maximum Suspend clock frequency is 125 MHz" >>>>> Cool, now do we have an upper bound for how many clock cycles it >>>>> takes to wake up the PHY? >>>> My understanding is this ep command does not wake up the SS PHY, the >>>> SS PHY still stays at P3 when execute this ep command. The time >>>> required here is to wait controller complete something for this ep >>>> command with 32K clock. >>> Sorry I made a mistake. You're right. Just checked with one of the RTL >>> engineers, and it doesn't need to wake up the phy. However, if it is >>> eSS speed, it may take longer time as the command may be completing >>> with the suspend clock. >>> >> What's the value for GCTL[7:6]? > 2'b00 > > Thanks > Li Jun
(Sorry for the delay reply) If it's 0, then the ram clock should be the same as the bus_clk, which is odd since you mentioned that the suspend_clk is used instead while in P3. Anyway, I was looking for a way maybe to improve the speed during issuing a command. One way is to set GUSB3PIPECTL[17]=0, and it should wakeup the phy anytime. I think Felipe suggested it. It's odd that it doesn't work for you. I don't have other ideas beside increasing the command timeout. Thanks, Thinh
