On 11/7/2018 9:40 AM, Al Cooper wrote: > On 11/7/18 12:29 PM, Florian Fainelli wrote: >> On 11/7/18 8:27 AM, Alan Stern wrote: >>> On Wed, 7 Nov 2018, Al Cooper wrote: >>> >>>> On 11/7/18 10:23 AM, Alan Stern wrote: >>>>> On Tue, 6 Nov 2018, Florian Fainelli wrote: >>>>> >>>>>> On 11/6/18 1:40 PM, Al Cooper wrote: >>>>>>> On 11/6/18 11:08 AM, Alan Stern wrote: >>>>>>>> On Mon, 5 Nov 2018, Al Cooper wrote: >>>>>>>> >>>>>>>>> Add support for Broadcom STB SoC's to the ohci platform driver. >>>>>>>>> >>>>>>>>> Signed-off-by: Al Cooper <alcooperx@xxxxxxxxx> >>>>>>>>> --- >>>>>>>> >>>>>>>>> @@ -177,6 +189,8 @@ static int ohci_platform_probe(struct >>>>>>>>> platform_device *dev) >>>>>>>>> ohci->flags |= OHCI_QUIRK_FRAME_NO; >>>>>>>>> if (pdata->num_ports) >>>>>>>>> ohci->num_ports = pdata->num_ports; >>>>>>>>> + if (pdata->suspend_without_phy_exit) >>>>>>>>> + hcd->suspend_without_phy_exit = 1; >>>>>>>> >>>>>>>> Sorry if I missed this in the earlier discussions... Is there any >>>>>>>> possibility of adding a DT binding that could express this >>>>>>>> requirement, >>>>>>>> instead of putting it in the platform data? >>>>>>>> >>>>>>>> Alan Stern >>>>>>>> >>>>>>> >>>>>>> Alan, >>>>>>> >>>>>>> That was my original approach but internal review suggested that >>>>>>> I use >>>>>>> pdata instead. Below is my original patch for: >>>>>> >>>>>> And the reason for that suggestion was really because it was >>>>>> percevied >>>>>> as encoding a driver behavior as a Device Tree property as opposed to >>>>>> describing something that was inherently and strictly a hardware >>>>>> behavior (therefore suitable for Device Tree). >>>>> >>>>> Right. The best way to approach this problem is to identify and >>>>> characterize the hardware behavior which makes this override >>>>> necessary. >>>>> Then _that_ can be added to DT, since it will be a property of the >>>>> hardware rather than of the driver. >>>>> >>>>>>> Add the ability to skip calling the PHY's exit routine on suspend >>>>>>> and the PHY's init routine on resume. This is to handle a USB PHY >>>>>>> that should have it's power_off function called on suspend but >>>>>>> cannot >>>>>>> have it's exit function called because on exit it will disable the >>>>>>> PHY to the point where register accesses to the Host Controllers >>>>>>> using the PHY will be disabled and the host drivers will crash. >>>>> >>>>> What's special about this PHY? Why does the exit function mess the >>>>> PHY >>>>> up? Or to put it another way, why doesn't the exit function mess up >>>>> other PHYs in the same way? >>>>> >>>>> For that matter, can we change the code so that suspend doesn't call >>>>> the exit function for _any_ PHY? Will just calling the power_off >>>>> function be good enough? If not, then why not? >>>>> >>>>> Alan Stern >>>>> >>>> >>>> In our USB hardware the USB PHY supplies a clock for the EHCI/OHCI and >>>> XHCI host controllers and if the PHY is totally shut down the EHCI, >>>> OHCI >>>> and XHCI registers will cause an exception if accessed and cause the >>>> EHCI, OHCI and XHCI drivers to crash. There is always talk of fixing >>>> this in the hardware by adding an aux clock that will takeover when the >>>> PHY clock is shut down, but this hasn't happened yet. It seems like >>>> "exit on suspend" still makes sense on systems that don't have this >>>> problem (additional power savings?) so removing the exit on suspend for >>>> all systems is not a good idea. >>> >>> Then in theory you should be able to add a Device Tree property which >>> says that the PHY provides a clock for the USB host controller. That >>> is strictly a property of the hardware; it has nothing to do with the >>> driver. Therefore it is appropriate for DT. >> >> The very compatible string that is being allocated/defined for this >> controller carries that information already, that is, if you probe a >> "brcm,bcm7445-ohci" compatible then that means the controller has a >> dependency on the PHY to supply its clock. >> >> Adding a property vs. keying on the compatible string makes sense if you >> know there is at least a second consumer of that property (unless we >> make it a broadcom specific property, in which case, it really is >> redundant with the compatible string). >> >> Anyway, my grudge with that property was the name chosen initially, >> which included an action to be performed by an implementation as opposed >> to something purely descriptive. E.g: 'phy-supplies-clock' might be okay. >> >>> >>> Wouldn't this solve your issue? >> >> It would not change much except that there is no need to much with >> ohci-platform.c anymore, but ultimately that property needs to be read >> by ohci-hcd.c and acted on, which would likely lead to the same amount >> of changes as those present in patch #2 currently. >> > We also need this functionality in the EHCI and XHCI drivers and it's > not the ohci-hcd.c module that needs to know, it's the core/phy.c module > called from core/hcd.c. So in that regard the Device Tree property would actually scale a bit better in that you would no longer need to modify the various *hci-plat*.c files, if that is the way to go, then sure. -- Florian
