On Monday 05 December 2016 10:17 PM, Bin Liu wrote: > On Fri, Dec 02, 2016 at 03:23:50PM +0100, Alexandre Bailon wrote: >> On 11/29/2016 06:56 PM, Bin Liu wrote: >>> On Tue, Nov 29, 2016 at 06:41:04PM +0100, Alexandre Bailon wrote: >>>> On 11/29/2016 05:16 PM, Bin Liu wrote: >>>>> Hi, >>>>> >>>>> On Mon, Nov 28, 2016 at 05:26:20PM +0100, Alexandre Bailon wrote: >>>>>> On da8xx, VBUS is not maintained during suspend when musb is in host >>>>>> mode. >>>>>> On resume, all the connected devices will be disconnected and then will >>>>>> be enumerated again. >>>>>> This happens because MUSB_DEVCTL is cleared during suspend. >>>>>> Add a quirk to preserve MUSB_DEVCTL during a suspend. >>>>> >>>>> Will preserving MUSB_DEVCTL prevent the device getting disconnected? >>>> Yes. Preserving MUSB_DEVCTL keeps VBUS on though the PHY is off during >>>> suspend. >>> >>> VBUS will be on, but does it prevent disconnecting the usb device on >>> resume? I don't have a DA8xx to test, but I doubt it, since the PHY is >>> off. >> Actually, the PHY is not really off. > > I guess the PHY should be off when the system is suspended for an > aggressive power saving. > > Sekhar, any comments?
No, nothing from my side. I haven't really played with this side of DA850 at all. For your reference, this is what chapter 10.11.1 referenced by Alexandre says: " The USB modules can be clock gated using the PSC; however, this does not power down/clock gate the PHY logic. You can put the USB2.0 PHY and OTG module in the lowest power state, when not in use, by writing to the USB0PHYPWDN and the USB0OTGPWRDN bits in the Chip Configuration 2 Register (CFGCHIP2) in the System Configuration (SYSCFG) Module chapter. " It is little bit ambiguous on if USB0PHYPWDN and USB0OTGPWRDN do really power down the PHY. I would just program the bits suggested by the manual and assume that the hardware reaches the safest low power state it can reach. Thanks, Sekhar -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
