Hi Knud,
I haven't reviewed or tested the whole patch yet, but I like the idea in concept. One thing that made me pause though is the way that the check_mbox flag is handled. You have it protected by a semaphore (implying you're expecting it to get used concurrently), but you have non-atomic test-and-then-set actions which will mean that if concurrent access is attempted multiple users might call prepare_check and check_mbox_set (causing some of them to be "lost", which may or may not be a problem), and then on failure one might call check_mbox_clear while another is still waiting for a check to occur (which seems like it would be a problem). Again, I haven't followed the logic all the way through yet so possibly this isn't a real problem, but it bothers me. J If the intent is to have only one concurrent state machine trigger a check datagram at a time (which it seems like it is), then you should probably be using an atomic test-and-set operation instead. Additionally it doesn't look like you have any protection against concurrent CoE access (which TBH I'm not entirely sure whether this occurs, but Frank's patch 27 suggests it does), and I'm definitely not a fan of allocating/deallocating memory on each mailbox transfer, which is what it looks like you're doing. Regards, Gavin Lambert From: etherlab-dev-boun...@etherlab.org [mailto:etherlab-dev-boun...@etherlab.org] On Behalf Of Knud Baastrup Sent: Wednesday, 25 June 2014 01:13 To: etherlab-dev@etherlab.org Subject: Re: [etherlab-dev] Support for multiple mailbox protocols Hi ! I just discovered that the provided patch included a hardcoded mailbox size that I have now replaced with a dynamic allocated buffer. I have attached a new patch (ethercat_152_stable_mailbox_1.patch) that fully replaces the prior patch (ethercat_152_stable_mailbox.patch). Thanks, Knud Baastrup From: etherlab-dev-boun...@etherlab.org [mailto:etherlab-dev-boun...@etherlab.org] On Behalf Of Knud Baastrup Sent: 23. juni 2014 14:27 To: etherlab-dev@etherlab.org Subject: [etherlab-dev] Support for multiple mailbox protocols Hello Florian, Gavin, Frank (and others facing the lack of support for multiple mailbox protocols) I have like Frank Heckenbach and Gavin also struggled with the lack of support for multiple mailbox protocols and came up with an alternative solution to the one provided by Frank in patch 9-10-11. I have attached the patch that is based on the stable-1.5 branch. The patch should support all the mailbox protocols, but has only been tested with CoE, EoE and FoE. I will in few lines try to summarize the patch: In this patch I accept that a mailbox read request (e.g. FP-RD) for a given mailbox protocol can return data from any other mailbox protocol running at the same time. The data returned by a read datagram is therefore stored in a separate buffer for each mailbox protocol instead of the datagram data buffer. The mailbox state machines will check and fetch the data from their own buffer instead of the datagram buffer (that is no longer used for mailbox read data). A check_mbox flag is introduced to track when a given slave has an ongoing mailbox read request. In normal case the mailbox state machine will run as previously if no mailbox read request is ongoing, but if a mailbox read-request is ongoing (check_mbox flag is set) it will check its own mailbox buffer (as the ongoing mailbox read request might have returned its data) and otherwise wait until the read request is done and it gets the opportunity to reserve the mailbox for its own read request. Venlig hilsen / Best regards, Knud Baastrup DEIF Wind Power Technology SW Developer Direct.: +45 9614 8458 E-mail: <mailto:k...@deif.com> k...@deif.com --------------------------------------------------------------- Retrofit your Vestas COTAS controller and optimize availability that will improve your annual energy generation, reduce service cost and extend the lifetime of your turbine. V27 V39 V44 V47 <http://www.deifwindpower.com/retrofit.aspx?utm_source=Retrofit&utm_medium=e mail%20signatur&utm_term=Retrofit%2BVestas%2BCOTAS&utm_content=textlink&utm_ campaign=Retrofit> Read more about DEIF's solutions to retrofit your turbines on our website
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