| Message ID | 1386807659-5505-1-git-send-email-notasas@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, Dec 12, 2013 at 02:20:59AM +0200, Grazvydas Ignotas wrote: > This is a hard to reproduce problem which leads to non-functional > USB-OTG port in 0.1%-1% of all boots. Tracked it down to commit > e25bec160158abe86c "omap2+: save and restore OTG_INTERFSEL", > which introduces save/restore of OTG_INTERFSEL over suspend. > > Since the resume function is also called early in driver init, it uses a > non-initialized value (which is 0 and a non-supported setting in DM37xx > for INTERFSEL). Shortly after the correct value is set. Apparently this > works most time, but not always. > > Fix it by not writing the value on runtime resume if it is 0 > (0 should never be saved in the context as it's invalid value, > so we use it as an indicator that context hasn't been saved yet). > > This issue was originally found by Andreas Naumann: > http://marc.info/?l=linux-usb&m=138562574719654&w=2 > > Reported-and-bisected-by: Andreas Naumann <anaumann@ultratronik.de> > Signed-off-by: Grazvydas Ignotas <notasas@gmail.com> > Cc: <stable@vger.kernel.org> > --- > This is a regression from 3.2, so should go to -rc and stable, IMO. > It's really annoying issue if you want to have a stable OTG behavior, > I've burned quite a lot of time on it myself over a year ago and gave up > eventually. Good thing Andreas finally found it, many thanks to him! > > drivers/usb/musb/omap2430.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/usb/musb/omap2430.c b/drivers/usb/musb/omap2430.c > index 2a408cd..737b3da 100644 > --- a/drivers/usb/musb/omap2430.c > +++ b/drivers/usb/musb/omap2430.c > @@ -672,7 +672,8 @@ static int omap2430_runtime_resume(struct device *dev) > > if (musb) { > omap2430_low_level_init(musb); > - musb_writel(musb->mregs, OTG_INTERFSEL, > + if (musb->context.otg_interfsel != 0) You might want to write an inline comment explaining why you're checking otg_interfsel for 0 here (as you explained 0 is not a valid value to be found). Br, David > + musb_writel(musb->mregs, OTG_INTERFSEL, > musb->context.otg_interfsel); > phy_power_on(musb->phy); > } > -- > 1.7.9.5 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-usb" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/usb/musb/omap2430.c b/drivers/usb/musb/omap2430.c index 2a408cd..737b3da 100644 --- a/drivers/usb/musb/omap2430.c +++ b/drivers/usb/musb/omap2430.c @@ -672,7 +672,8 @@ static int omap2430_runtime_resume(struct device *dev) if (musb) { omap2430_low_level_init(musb); - musb_writel(musb->mregs, OTG_INTERFSEL, + if (musb->context.otg_interfsel != 0) + musb_writel(musb->mregs, OTG_INTERFSEL, musb->context.otg_interfsel); phy_power_on(musb->phy); }
This is a hard to reproduce problem which leads to non-functional USB-OTG port in 0.1%-1% of all boots. Tracked it down to commit e25bec160158abe86c "omap2+: save and restore OTG_INTERFSEL", which introduces save/restore of OTG_INTERFSEL over suspend. Since the resume function is also called early in driver init, it uses a non-initialized value (which is 0 and a non-supported setting in DM37xx for INTERFSEL). Shortly after the correct value is set. Apparently this works most time, but not always. Fix it by not writing the value on runtime resume if it is 0 (0 should never be saved in the context as it's invalid value, so we use it as an indicator that context hasn't been saved yet). This issue was originally found by Andreas Naumann: http://marc.info/?l=linux-usb&m=138562574719654&w=2 Reported-and-bisected-by: Andreas Naumann <anaumann@ultratronik.de> Signed-off-by: Grazvydas Ignotas <notasas@gmail.com> Cc: <stable@vger.kernel.org> --- This is a regression from 3.2, so should go to -rc and stable, IMO. It's really annoying issue if you want to have a stable OTG behavior, I've burned quite a lot of time on it myself over a year ago and gave up eventually. Good thing Andreas finally found it, many thanks to him! drivers/usb/musb/omap2430.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)