Hi On Mon, Apr 10, 2017 at 1:57 PM, Kishon Vijay Abraham I <kishon@xxxxxx> wrote: > Hi, > > On Monday 10 April 2017 12:57 PM, Raviteja Garimella wrote: >> Hi, >> >> On Mon, Apr 10, 2017 at 10:55 AM, Kishon Vijay Abraham I <kishon@xxxxxx> wrote: >>> Hi, >>> >>> On Wednesday 05 April 2017 07:40 PM, Raviteja Garimella wrote: >>>> Hi Kishon, >>>> >>>> On Wed, Apr 5, 2017 at 7:04 PM, Kishon Vijay Abraham I <kishon@xxxxxx> wrote: >>>>> Hi Ravi, >>>>> >>>>> On Wednesday 05 April 2017 06:30 PM, Raviteja Garimella wrote: >>>>>> Hi Kishon, >>>>>> >>>>>> On Wed, Apr 5, 2017 at 4:30 PM, Kishon Vijay Abraham I <kishon@xxxxxx> wrote: >>>>>>> Hi, >>>>>>> >>>>>>> On Tuesday 28 March 2017 05:57 PM, Raviteja Garimella wrote: >>>>>>>> This is driver for USB DRD Phy used in Broadcom's Northstar2 >>>>>>>> SoC. The phy can be configured to be in Device mode or Host >>>>>>>> mode based on the type of cable connected to the port. The >>>>>>>> driver registers to extcon framework to get appropriate >>>>>>>> connect events for Host/Device cables connect/disconnect >>>>>>>> states based on VBUS and ID interrupts. >>>>>>> >>>>>>> $patch should be phy: phy-bcm-ns2-usbdrd: USB DRD Phy driver for Broadcoms >>>>>>> Northstar2. >>>>>>> >>>>>> >>>>>> Will do. >>>>>> >>>>>>> Sorry for not letting you know this earlier. But I feel the design of the >>>>>>> driver should be changed. Extcon shouldn't be used here. The extcon >>>>>>> notifications should be sent to the consumer driver and the consumer driver >>>>>>> should be responsible for invoking the phy ops. >>>>>>> >>>>>> >>>>>> The consumer drivers here would be a UDC driver (USB device >>>>>> controller), EHCI and OHCI host controller drivers. >>>>>> I was already suggested in UDC driver review to deal with extcon in Phy driver. >>>>>> >>>>>> This phy connects to 2 host controllers, and one device controller. >>>>>> That's the design in Broadcom Northstar2 >>>>>> platform. The values of the VBUS and ID pins of this port are >>>>>> determined based on the type of the cable (device cable >>>>>> or host cable). And. phy has to be configured accordingly. >>>>>> >>>>>>> The phy ops being invoked during extcon events doesn't look right. >>>>>> >>>>>> Could you please elaborate on the concern, so that we can think of >>>>>> mitigating those issues in this driver? >>>>>> Since we are dealing with phy init/shutdown in this driver itself, are >>>>>> you okay with moving the extcon handling code >>>>>> out of phy ops ? >>>>> >>>>> yeah, For e.g., ns2_drd_phy_init is part of phy_ops and is being invoked from >>>>> extcon events too. Can a phy which is initialized by a phy consumer (say your >>>>> UDC invokes phy_init) can be shutdown by an extcon event? >>>>> >>>>> Maybe a clear explanation of when phy_ops here will be invoked and when it will >>>>> set using extcon events might help. >>>>> >>>> >>>> Say, we have a USB pendrive which is connected to the DRD port through >>>> a host cable. >>>> Now the PHY will be initialized to be in host mode. >>>> When the pendrive is unplugged, and we now connect the NS2 device to >>>> some linux PC, >>>> now the PHY has to be shutdown, and re-initialized to be in Device mode. >>>> >>>> On unplug event, it is set neither to Host nor Device mode (basically >>>> shutdown). Next time which ever cable is connected, the PHY is >>>> initialized to the respective >>>> mode. >>>> >>>> Please let me know if it's fine to do these initializations outside >>>> phy ops, because those will >>>> be irrelevant for phy consumers (the controllers) as it's anyways >>>> dealt in the phy driver through >>>> extcon. >>> >>> How does the consumer get to know whether they have to operate in host mode or >>> device mode? >>> >> In NS2, we have host controllers and device controller (not OTG/other >> that can switch >> between host and device mode). It's only phy that can be in host/device mode. >> Since both Host Controllers and Device Controller are connected to the same PHY, >> it is based on the extcon logic (the type of cable connected) that PHY >> will be in one >> of the modes host/device and the respective controller will operate. > > So at a point of time either the host controller or the device controller will > be active? and the PHY decides which of them should be active? Is that right? > Yes Thanks, Ravi > Thanks > Kishon -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
