On Tue, Nov 28, 2017 at 11:03:50AM +0200, Felipe Balbi wrote: > Ladislav Michl <ladis@xxxxxxxxxxxxxx> writes: > > On Tue, Nov 28, 2017 at 08:33:28AM +0100, Greg KH wrote: > >> On Mon, Nov 27, 2017 at 11:08:33PM +0100, Ladislav Michl wrote: > >> > Hi there, > >> > > >> > USB hosts do not discover any connected device on OMAP3 based board > >> > with CONFIG_PM=n. Just enabling this option is enough to restore working > >> > behaviour. Nothing unusual in log. Tested 4.14.2 and 4.15-rc1. I know > >> > a lot of stuff depends on CONFIG_PM, but is this expected behaviour? > >> > Neither EHCI nor MUSB is working without CONFIG_PM. > >> > >> What bus type is your controllers on? PCI? platform? Something else? > > > > Platform controllers inside OMAP3630 Soc. > > > >> And yes, perhaps this is to be expected, why would you not want > >> CONFIG_PM to be enabled? :) > > > > For a start, I know Linux is general purpose OS and I know I cannot expect > > low latency or low jitter when dealing with interrupts. > > > > Original problem is described here: > > https://www.spinics.net/lists/linux-omap/msg140081.html > > > > Shortly, with CONFIG_PM jitter of GPIO interrupt is about 350us which > > renders IR receiver unuseable - is cannot reliably decode IR protocol > > (gpio-ir-recv is used). With CONFIG_PM disabled, jitter is around 30us > > and that's enough to make IR decoders work. > > > > And as I was unable to fix it, nor anyone provided useful hint, I though > > I could work around problem from another side. And here we are... > > Isn't it enough to just set a huge timeout for GPIO's runtime_pm? You > can do that through sysfs. Just write a big number to the GPIO's > autosuspend_delay_ms file. This should help you: That does not help. And I already have Tony's hack in the patch stack: https://patchwork.kernel.org/patch/9643499/ So this part of SoC is not powered off at all. > modified drivers/gpio/gpio-omap.c > @@ -1238,6 +1238,8 @@ static int omap_gpio_probe(struct platform_device *pdev) > > platform_set_drvdata(pdev, bank); > > + pm_runtime_use_autosuspend(dev); > + pm_runtime_set_autosuspend_delay(dev, 60000); > pm_runtime_enable(dev); > pm_runtime_irq_safe(dev); > pm_runtime_get_sync(dev); > > > -- > balbi -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
