Hi, John Stultz wrote: > On Fri, Jan 8, 2021 at 4:26 AM Felipe Balbi <balbi@xxxxxxxxxx> wrote: >> >> Hi, >> >> John Stultz <john.stultz@xxxxxxxxxx> writes: >>> From: Yu Chen <chenyu56@xxxxxxxxxx> >>> >>> Just resending this, as discussion died out a bit and I'm not >>> sure how to make further progress. See here for debug data that >>> was requested last time around: >>> https://urldefense.com/v3/__https://lore.kernel.org/lkml/CALAqxLXdnaUfJKx0aN9xWwtfWVjMWigPpy2aqsNj56yvnbU80g@xxxxxxxxxxxxxx/__;!!A4F2R9G_pg!LNzuprAeg-O80SgolYkIkW4-ne-M-yLWCDUY9MygAIrQC398Z6gRJ9wnsnlqd3w$ >>> >>> With the current dwc3 code on the HiKey960 we often see the >>> COREIDLE flag get stuck off in __dwc3_gadget_start(), which >>> seems to prevent the reset irq and causes the USB gadget to >>> fail to initialize. >>> >>> We had seen occasional initialization failures with older >>> kernels but with recent 5.x era kernels it seemed to be becoming >>> much more common, so I dug back through some older trees and >>> realized I dropped this quirk from Yu Chen during upstreaming >>> as I couldn't provide a proper rational for it and it didn't >>> seem to be necessary. I now realize I was wrong. >>> >>> After resubmitting the quirk, Thinh Nguyen pointed out that it >>> shouldn't be a quirk at all and it is actually mentioned in the >>> programming guide that it should be done when switching modes >>> in DRD. >>> >>> So, to avoid these !COREIDLE lockups seen on HiKey960, this >>> patch issues GCTL soft reset when switching modes if the >>> controller is in DRD mode. >>> >>> Cc: Felipe Balbi <balbi@xxxxxxxxxx> >>> Cc: Tejas Joglekar <tejas.joglekar@xxxxxxxxxxxx> >>> Cc: Yang Fei <fei.yang@xxxxxxxxx> >>> Cc: YongQin Liu <yongqin.liu@xxxxxxxxxx> >>> Cc: Andrzej Pietrasiewicz <andrzej.p@xxxxxxxxxxxxx> >>> Cc: Thinh Nguyen <thinhn@xxxxxxxxxxxx> >>> Cc: Jun Li <lijun.kernel@xxxxxxxxx> >>> Cc: Mauro Carvalho Chehab <mchehab+huawei@xxxxxxxxxx> >>> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> >>> Cc: linux-usb@xxxxxxxxxxxxxxx >>> Signed-off-by: Yu Chen <chenyu56@xxxxxxxxxx> >>> Signed-off-by: John Stultz <john.stultz@xxxxxxxxxx> >>> --- >>> v2: >>> * Rework to always call the GCTL soft reset in DRD mode, >>> rather then using a quirk as suggested by Thinh Nguyen >>> >>> v3: >>> * Move GCTL soft reset under the spinlock as suggested by >>> Thinh Nguyen >> Because this is such an invasive change, I would prefer that we get >> Tested-By tags from a good fraction of the users before applying these >> two changes. > I'm happy to reach out to folks to try to get that. Though I'm > wondering if it would be better to put it behind a dts quirk flag, as > originally proposed? > https://urldefense.com/v3/__https://lore.kernel.org/lkml/20201021181803.79650-1-john.stultz@xxxxxxxxxx/__;!!A4F2R9G_pg!LNzuprAeg-O80SgolYkIkW4-ne-M-yLWCDUY9MygAIrQC398Z6gRJ9wnRWITZfc$ > > That way folks can enable it for devices as they need? > > Again, I'm not trying to force this in as-is, just mostly sending it > out again for discussion to understand what other approach might work. > > thanks > -john A quirk would imply something is broken/diverged from the design right? But it's not the case here, and at least this is needed for HiKey960. Also, I think Rob will be ok with not adding 1 more quirk to the dwc3 devicetree. :) BR, Thinh
