> -----Original Message----- > From: Martin Kepplinger <martin.kepplinger@xxxxxxx> > Sent: 2020年2月20日 19:44 > To: Jun Li <jun.li@xxxxxxx>; Peter Chen <peter.chen@xxxxxxx>; > mathias.nyman@xxxxxxxxx > Cc: linux-usb@xxxxxxxxxxxxxxx; dl-linux-imx <linux-imx@xxxxxxx>; Anson Huang > <anson.huang@xxxxxxx>; shawnguo@xxxxxxxxxx; kernel@xxxxxxxxxxxxxx > Subject: Re: [PATCH] usb: host: xhci-plat: add XHCI_MISSING_CAS quirk > > On 20.02.20 07:31, Jun Li wrote: > >> -----Original Message----- > >> From: Martin Kepplinger <martin.kepplinger@xxxxxxx> > >> Sent: 2020年2月20日 1:37 > >> To: Jun Li <jun.li@xxxxxxx>; Peter Chen <peter.chen@xxxxxxx>; > >> mathias.nyman@xxxxxxxxx > >> Cc: linux-usb@xxxxxxxxxxxxxxx; dl-linux-imx <linux-imx@xxxxxxx>; > >> Anson Huang <anson.huang@xxxxxxx>; shawnguo@xxxxxxxxxx; > >> kernel@xxxxxxxxxxxxxx > >> Subject: [PATCH] usb: host: xhci-plat: add XHCI_MISSING_CAS quirk > >> > >> From: Li Jun <jun.li@xxxxxxx> > >> > >> i.MX8MQ USB3 host needs XHCI_MISSING_CAS quirk to warm reset the port > >> to enum the > >> USB3 device plugged in while system sleep, as the port state is stuck > >> in polling mode after resume. > >> > >> Signed-off-by: Li Jun <jun.li@xxxxxxx> > >> Acked-by: Peter Chen <peter.chen@xxxxxxx> > >> --- > >> > >> Hi, > >> > >> Because resume from S3 suspend is broken for me on imx8mq, I stumbled > >> upon this patch in NXP's linux tree. (Please note that I'm not the > >> author and I've not yet put my SoB tag under it). This is just a > >> question: > >> > >> This patch (and the docs) clearly is missing in mainline Linux > >> because the imx8mq devicetree description includes it (which does nothing now). > >> > >> I've tested this and this particular addition doesn't fix my problem: > >> > >> [ 84.257538] imx8mq-usb-phy 381f0040.usb-phy: bus resume > >> [ 84.263195] imx8mq-usb-phy 382f0040.usb-phy: bus resume > >> [ 84.268898] dwc3 38100000.usb: driver resume > >> > >> during resume from S3 suspend, here it still hangs. > > > > Is your problem a system hang? If yes, this may another issue, where > > the hang happens? dwc3_resume_common()? > > exactly! I followed to the point it hangs once again and it's > > dwc3_core_init() called from dwc3_resume_common()'s "OTG" case. > > Specifically, dwc3_writel() is what I don't get past: > https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Felixir.bootl > in.com%2Flinux%2Fv5.6-rc2%2Fsource%2Fdrivers%2Fusb%2Fdwc3%2Fcore.c%23L934& > data=02%7C01%7Cjun.li%40nxp.com%7C130cd29875c44792d1a908d7b5fa2516%7C686ea1d3b > c2b4c6fa92cd99c5c301635%7C0%7C0%7C637177958284696041&sdata=mqh9MH6ESLVxKvW > vvMq4vwt2dcTuvNopgGVdXEbbMwk%3D&reserved=0 So while dwc3 resume, the first register access cause hang. Looks like some required clocks or power domain of USB0 is not on. > > do you have an idea why this writel() hangs? I never encounter such hang on my iMX8MQ EVK board using upstream kernel(5.x) + changes of enable USB0 port, but I didn't try latest 5.6 kernel. I will enable the first port based on Linux-next to give a try on my NXP iMX8MQ EVK board, do you think I can reproduce your problem? Li Jun > > > > > The question patch is to give a warm reset for connected USB device if > > the link state is not connect/CAS after system resume, otherwise host > > will wait 2s for device appear: > > > > [ 44.834831] usb 2-1: Waited 2000ms for CONNECT > > ... > > [ 45.055718] PM: resume devices took 3.132 seconds > > > > I will post this patch and doc(to be updated) to upstream later. > > > > ok, good, thanks, > > martin
