From: Clemens Gruber <clemens.gruber@pqgruber.com>
To: Peter Chen <hzpeterchen@gmail.com>
Cc: linux-usb@vger.kernel.org,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
linux-kernel@vger.kernel.org
Subject: Re: chipidea: udc: kernel panic in isr_setup_status_phase
Date: Fri, 2 Sep 2016 18:42:43 +0200 [thread overview]
Message-ID: <20160902164243.GA4549@archie.localdomain> (raw)
In-Reply-To: <20160902015552.GE11262@shlinux2>
On Fri, Sep 02, 2016 at 09:55:52AM +0800, Peter Chen wrote:
> Do you have other 5V to USB_H1_VBUS? USB PHY needs 5V input voltage
> as the source for USB LDO (3.0v), either from OTG or Host 1. I suspect
> the lower vbus voltage causes the USB LDO voltage less than 3.0v, then
> cause the unstable for USB PHY. If possible, you can connect MAIN 5V
> (if it exists) directly to USB_H1_VBUS to see if this problem is fixed.
Yes, USB_H1_VBUS is supplied from internal 5V and it is accurate (+/-
0.03V). The USB_H_EN signal enables USB_H1_VBUS through a MIC2026-1.
The USB_OTG_VBUS signal from the picture with 4.69V came from the host
PC and is not under our control.
I read in the ReferenceManual that the USBPHY defaults to USB_H1_VBUS if
both USB_OTG_VBUS and USB_H1_VBUS are available.
If we imagine the following situation: USB OTG cable is plugged-in, the
board is powered on, USB_OTG_VBUS is supplied externally and USBPHY uses
it because USB_H1_EN is not high yet and did not enable USB_H1_VBUS.
If the USBPHY started out being supplied by USB_OTG_VBUS and later on,
USB_H1_VBUS comes up, will the USBPHY switch to USB_H1_VBUS immediately
or stay at being supplied by USB_OTG_VBUS as long as that is available?
> Great. Can you see the sudden lower for vbus again? If it still exists, it may
> be GND issue.
Yes it is still visible. Does not seem to be a problem though.
> Avoid NULL pointer deference is necessary. Patch is welcome :)
Yes, but should we also stop the gadget driver and print an error
message? Or just return from the isr and neither report nor stop?
Regards,
Clemens
next prev parent reply other threads:[~2016-09-02 16:42 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-23 0:36 Clemens Gruber
2016-08-24 8:11 ` Peter Chen
2016-08-25 23:47 ` Clemens Gruber
2016-08-26 17:21 ` Peter Chen
2016-08-28 18:15 ` Clemens Gruber
2016-08-29 10:24 ` Peter Chen
2016-08-30 17:20 ` Clemens Gruber
2016-09-02 1:55 ` Peter Chen
2016-09-02 16:42 ` Clemens Gruber [this message]
2016-09-05 3:10 ` Peter Chen
2016-09-05 17:24 ` Clemens Gruber
2016-08-26 17:22 ` Peter Chen
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