Date: Sat, 31 Dec 2011 08:01:22 -0800 From: Adrian Chadd <adrian@freebsd.org> To: Stefan Bethke <stb@lassitu.de> Cc: Aleksandr Rybalko <ray@ddteam.net>, freebsd-mips@freebsd.org Subject: Re: arge problem on MR3420 Message-ID: <CAJ-VmoncaNavvGns9dM_Kc_BiuKNbNpmNijiYKAOh13bQ967Rw@mail.gmail.com> In-Reply-To: <2A05E0AA-5AA5-47FD-90EA-BD6B23A01EFE@lassitu.de> References: <B40E8E4D-115F-46EF-A51F-52E562EF166E@lassitu.de> <CAJ-VmokWLzfjd%2B=_=tSt7ukc=gK2kd9H5s7sH-7bbzSpzBFUcQ@mail.gmail.com> <20111231000638.d257448c.ray@ddteam.net> <98BA8EF5-E808-43F8-92A8-68B14CAF998F@lassitu.de> <2A05E0AA-5AA5-47FD-90EA-BD6B23A01EFE@lassitu.de>
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On 31 December 2011 04:36, Stefan Bethke <stb@lassitu.de> wrote: > Am 30.12.2011 um 23:49 schrieb Stefan Bethke: > >> OK, trying to pull in everyone. =A0There seems to be a problem with if_a= rge on certain chips/platforms. =A0I've encountered it on TL-MR3420 and WRT= -160NL. =A0I'm currently working off Adrians gitorious repo. > > The problem is limited to BOOTP; if I mount a USB stick as root, I can br= ing up arge1 without issue. > > On the AR7241, arge0 is connected to a phy and the blue WAN port, arge1 i= s connected to the built-in switch. =A0The port speeds are fixed (1000 for = the switch, 100 for the phy). > > With BOOTP enabled, I'm getting an interrupt storm on intr 3. =A0I've ena= bled debugging for arge, and it seems there is a TX underrun that is not be= ing cleared in that case. =A0I'm not fully understanding the code, so I'm n= ot sure why the TX underrun is not being cleared, or keeps reoccurring. Is the bootp code somehow tickling the interface setup in a way that isn't the same as the userland-driven config? Ie, a tx underrun should only occur if it runs out of TX descriptor slots. That's fine, it just means that it go to the end of the descriptor list. It's not _necessarily_ an error condition. And it should only _keep_ occuring if someone/something keeps tickling the DMA_TX_CONTROL_EN bit. So when the underrun occurs, what's the state of the TX ring head/tail poin= ters? The code in arge_intr() should be self explanatory. If any frames were sent, call arge_start_locked(). The call to arge_encap() throws something into the TX ring and then sets DMA_TX_CONTROL_EN. How about adding a printf() to arge_start_locked() and arge_encap(), see if they're constantly being called. Adrian
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