Date: Wed, 8 Jul 2009 10:58:17 +0200 From: Rafal Jaworowski <raj@semihalf.com> To: Hans Petter Selasky <hselasky@c2i.net> Cc: thompsa@freebsd.org, freebsd-arm@freebsd.org, freebsd-usb@freebsd.org Subject: Re: CPU Cache and busdma usage in USB Message-ID: <37C51279-42D8-49DE-8249-0DA386EBB062@semihalf.com> In-Reply-To: <200907071846.42086.hselasky@c2i.net> References: <200906231035.43096.kosmo@semihalf.com> <200907051236.22783.hselasky@c2i.net> <200907071550.28781.kosmo@semihalf.com> <200907071846.42086.hselasky@c2i.net>
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On 2009-07-07, at 18:46, Hans Petter Selasky wrote: >> I had Checked USB behaviour on PowerPC without hardware cache >> coherency. >> The problem also exists here and patch helps. > > In my source code view the busdma sync function is empty for power- > pc. Your > patch should have no effect at all for sync operations? This was about the PPC4xx PowerPC port, not committed to the tree yet. Unlike most PowerPC this system has a de-coherent DMA and therefore its busdma sync is non empty, but needs to enforce coherency by software. The point is this is another platform on which USB stack (usb_pc_cpu_* functions) shows similar issues as reported for ARM and MIPS. Rafal
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