Date: Tue, 18 Dec 2012 09:22:22 +0100 From: Hans Petter Selasky <hselasky@c2i.net> To: Andrew Turner <andrew@fubar.geek.nz> Cc: Oleksandr Tymoshenko <gonzo@freebsd.org>, freebsd-usb@freebsd.org Subject: Re: EHCI on armv6 with Write-Back caches Message-ID: <201212180922.22217.hselasky@c2i.net> In-Reply-To: <20121218204931.5322922d@fubar.geek.nz> References: <20121218204931.5322922d@fubar.geek.nz>
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On Tuesday 18 December 2012 08:49:31 Andrew Turner wrote: > Hello, > > Oleksandr and myself have been looking into why when we enable the > write-back cache on the PandaBoard there are kernel panics with USB. We > have tracked it down to an issue appending the ehci_qh_t to the list at > the end of ehci_setup_standard_chain(). > > I have a patch at [1] that allows me to run sha256 on a 40MB file over > NSF using the built in smsc USB ethernet chip. The problem is I have > had to place a call to DELAY before EHCI_APPEND_QH. This is obviously > not the correct solution. > > Is anyone able to help me narrow down what is missing? It appears to be > a missing cache invalidate or flush somewhere but I haven't been able > to track down what cache function the DELAY is working around. > > Andrew > > [1] http://fubar.geek.nz/files/freebsd/ehci_4.diff Hi, Can you dump the DMA tag belonging to the QH via and check wether it is mapped coherent or not. Thes QH- and TD- structures should not be cache mapped. Else cache has not been disabled on those pages. qh->page_cache->tag --HPS
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