Re: [Uclinux-dist-devel] net/dsa
On Tue, Jul 20, 2010 at 11:54 PM, Lennert Buytenhek buyt...@wantstofly.org wrote: On Tue, Jul 20, 2010 at 11:28:19PM +0200, Karl Beldan wrote: I found the dsa code very handy to help manage a switch. Ah. What particular part are you using? The whole thing but the cascading stuff. I could even reuse a tagging format almost as is! I meant, which silicon part, i.e. which hardware/chips? Anything with available data sheets? Yes, Micrel - ksz8863. Yet I was surprised I had to tweak the code to simply use the phy layer state machine. You mean that net/dsa uses phy_attach() but not phy_start_machine() ? Have you seen problems arising from this? I did not mean that, but I do not think there would be a problem, since every in-tree driver provide their poll_link() to do the job of the phylib's state_queue, unless one does not provide its poll_link(), I guess this is what you had in mind. What I had in mind in fact was the re-use of the phylib's interrupt based code, in this situation poll_link() is not there, but there replacing phy_attach() with phy_start_machine is not enough. We cannot rely on the switch's interrupt pin being hooked up -- there are many boards out where it's not wired up at all. Therefore, polling for link state changes is the only reliable and portable way. Not rely on it of course, but let the code handle it. (Of course, interrupt support can always be added, and that used instead of polling if a load-time test shows that the interrupt pin actually works.) Those are not big changes, but the code seems to aim at such versatile behavior (and more), I can only imagine it would be useful for the plethora of boards embedding a switch. Although it supports Marvell chips only for now, net/dsa was written to be able to handle other models of switch chips as well. As I said, I would love to see support for other switch chips added to it. The blackfin tree has a dsa driver for ksz8893, it is the only out-of-tree one I have seen so far. CCed them, I hope it is the right ML. So I was wondering if there was anybody playing with this code, or having ideas about features to add (vlan/stp callbacks) ? As far as I know, the code currently in the kernel works well for what it intends to do (which is to just expose the switch ports), and I'm not aware of any bugs in it. That said, you're right in that there are several more features that the hardware supports that the software could be extended to handle. For one, I don't have access to any Marvell switch chip hardware anymore, so that limits my ability to play with this. Also, the relevant documentation is under a rather restrictive license, so the only way I can see net/dsa support for Marvell parts improving is if there's pressure from a large enough customer to make this happen. Now I understand, but still, I am surprised nobody else touched the code, with all those switches in the embedded business. Me too.. ..then again, embedded people tend to hack up stuff in private and ship whatever works -- they aren't exactly known for working with upstream. Yeah, ... I know it too much. -- Karl ___ Uclinux-dist-devel mailing list Uclinux-dist-devel@blackfin.uclinux.org https://blackfin.uclinux.org/mailman/listinfo/uclinux-dist-devel
Re: [Uclinux-dist-devel] net/dsa
On Wed, Jul 21, 2010 at 02:33, Karl Beldan wrote: On Tue, Jul 20, 2010 at 11:54 PM, Lennert Buytenhek wrote: On Tue, Jul 20, 2010 at 11:28:19PM +0200, Karl Beldan wrote: I found the dsa code very handy to help manage a switch. Ah. What particular part are you using? The whole thing but the cascading stuff. I could even reuse a tagging format almost as is! I meant, which silicon part, i.e. which hardware/chips? Anything with available data sheets? Yes, Micrel - ksz8863. Yet I was surprised I had to tweak the code to simply use the phy layer state machine. You mean that net/dsa uses phy_attach() but not phy_start_machine() ? Have you seen problems arising from this? I did not mean that, but I do not think there would be a problem, since every in-tree driver provide their poll_link() to do the job of the phylib's state_queue, unless one does not provide its poll_link(), I guess this is what you had in mind. What I had in mind in fact was the re-use of the phylib's interrupt based code, in this situation poll_link() is not there, but there replacing phy_attach() with phy_start_machine is not enough. We cannot rely on the switch's interrupt pin being hooked up -- there are many boards out where it's not wired up at all. Therefore, polling for link state changes is the only reliable and portable way. Not rely on it of course, but let the code handle it. (Of course, interrupt support can always be added, and that used instead of polling if a load-time test shows that the interrupt pin actually works.) Those are not big changes, but the code seems to aim at such versatile behavior (and more), I can only imagine it would be useful for the plethora of boards embedding a switch. Although it supports Marvell chips only for now, net/dsa was written to be able to handle other models of switch chips as well. As I said, I would love to see support for other switch chips added to it. The blackfin tree has a dsa driver for ksz8893, it is the only out-of-tree one I have seen so far. CCed them, I hope it is the right ML. i had asked the guy who wrote the drivers in our tree about the status of these to see if they were pushable, but i guess he never got back to me. they are: net: dsa: introduce STPID switch tagging handling code http://git.kernel.org/?p=linux/kernel/git/vapier/blackfin.git;a=commit;h=315dac3e2172117de23b629a22af145238254f14 net: dsa: introduce MICREL KSZ8893MQL/BL ethernet switch chip support http://git.kernel.org/?p=linux/kernel/git/vapier/blackfin.git;a=commit;h=5e1196270de86a93f6e0548f732d832dc62f8ae9 since the guy who wrote it is no longer with us, i'll just post it and see what happens -mike ___ Uclinux-dist-devel mailing list Uclinux-dist-devel@blackfin.uclinux.org https://blackfin.uclinux.org/mailman/listinfo/uclinux-dist-devel
Re: [Uclinux-dist-devel] net/dsa
On Wed, Jul 21, 2010 at 08:57:11AM -0400, Mike Frysinger wrote: Although it supports Marvell chips only for now, net/dsa was written to be able to handle other models of switch chips as well. As I said, I would love to see support for other switch chips added to it. The blackfin tree has a dsa driver for ksz8893, it is the only out-of-tree one I have seen so far. CCed them, I hope it is the right ML. i had asked the guy who wrote the drivers in our tree about the status of these to see if they were pushable, but i guess he never got back to me. they are: net: dsa: introduce STPID switch tagging handling code http://git.kernel.org/?p=linux/kernel/git/vapier/blackfin.git;a=commit;h=315dac3e2172117de23b629a22af145238254f14 net: dsa: introduce MICREL KSZ8893MQL/BL ethernet switch chip support http://git.kernel.org/?p=linux/kernel/git/vapier/blackfin.git;a=commit;h=5e1196270de86a93f6e0548f732d832dc62f8ae9 since the guy who wrote it is no longer with us, i'll just post it and see what happens Looks mostly alright, needs some minor changes -- post the patches to netdev@ and CC me and I'll do a review there. thanks, Lennert ___ Uclinux-dist-devel mailing list Uclinux-dist-devel@blackfin.uclinux.org https://blackfin.uclinux.org/mailman/listinfo/uclinux-dist-devel
