**** BEGIN LOGGING AT Mon May 26 03:00:00 2014
May 26 04:19:19 <ds2> Abhishek_: it is a long wknd for the US
May 26 04:20:35 <mranostay> every weekend should be 3 days
May 26 04:33:30 <Abhishek_> I see
May 26 04:34:33 <Abhishek_> But no weekend is long enough ;)
May 26 04:50:21 <praveendath92> av500:
May 26 04:50:23 <praveendath92> ping
May 26 04:52:25 <praveendath92> I have difficulty finding the control endpoint of my usb device.
May 26 04:52:37 <praveendath92> Anyone any thoughts?
May 26 04:55:20 <Abhishek_> praveendath92:  libusb_control_transfer?
May 26 04:55:39 <praveendath92> Abhishek_: No libusb.
May 26 04:56:12 <praveendath92> Ideally a piece of code that can do what libusb_control_transfer does.
May 26 04:56:53 <Abhishek_> Is it for the kernel module?
May 26 04:57:27 <praveendath92> Yeah.
May 26 04:59:39 <praveendath92> Abhishek_: From line 41 here, https://github.com/praveendath92/bard-linux/blob/master/adk-driver.c
May 26 05:00:06 <praveendath92> I'm not able to find  a control endpoint. Nor is it listed in libusb -v
May 26 05:18:57 <Abhishek_> This happens after you switch the device to adk mode?
May 26 09:07:11 <praveendath92> vvu: ping
May 26 09:09:28 <karki> panto : ping!
May 26 09:29:13 <vvu> praveendath92: pong
May 26 09:34:30 <panto> karki, pong
May 26 09:39:09 * vvu likes how we are playing ping pong over here :)
May 26 09:41:57 <karki> panto : I'm reading up on sysfs. I wrote a sample driver yesterday that supported read, write, open and close. used "register_chrdev" and "mknod". That works for char drivers, but I'm wondering how to get a /dev entry for a platform drivers! (I haven't read platform drivers completely, so I could be missing out on an obvious way)
May 26 09:42:48 <panto> ls /sys/devices/platform/
May 26 09:43:08 <panto> you don't need a /dev/ entry
May 26 09:44:47 <karki> how do I support mmap? can I mmap a sysfs entry?
May 26 09:45:21 <karki> panto : currently  I have seen only show and store ....
May 26 09:46:39 <karki> anyway I'll check it out and get back to you in a while.
May 26 10:05:58 <karki> praveendath92 : vvu had ponged you while you were away.
May 26 10:06:19 <vvu> here
May 26 10:07:16 <Abhishek_> Hey panto
May 26 10:07:23 <panto> hey
May 26 10:11:15 * Abhishek_ hopes that panto did find time to review the code
May 26 10:15:00 <panto> took a look
May 26 10:15:04 <panto> seems fine
May 26 10:15:26 <panto> hope you now are aware about what the performance limits are in modern systems
May 26 10:15:41 <panto> it's not CPU processing, it's data movement and I/O
May 26 10:16:20 <panto> so you can stream data fast enough in DRAM, but then you can't really move them around easily, or process them
May 26 10:16:30 <panto> the UIO buffers are uncached too
May 26 10:17:10 <Abhishek_> So is that the reason for memcpy being slow?
May 26 10:17:13 <panto> mranostay mentioned that 25MHz is probably the fastest sampling rate you can do with the bone without some kind of special buffering
May 26 10:17:27 <panto> you're running out of memory bandwidth
May 26 10:17:45 <panto> when you have gobs of data, you better try not to move them around
May 26 10:17:54 <Abhishek_> Yep, saw that. I could add a LLT buffer if necessary.
May 26 10:18:10 <Abhishek_> Hardware is not an issue for me
May 26 10:18:43 <panto> performance of uncached memory is unsurprisingly bad for the main CPU
May 26 10:19:04 <Abhishek_> Can you suggest some head start for a 'zero copy' approach?
May 26 10:20:12 <panto> that's the scatter gather user-space access method we discussed
May 26 10:20:15 <panto> remember, the one with the many steps
May 26 10:24:19 <Abhishek_> panto: So how could I get into that? I think the first step would be to get a physical handle to a malloced buffer that I could give to the PRUs, right?
May 26 10:25:08 <panto> that's the problem
May 26 10:25:17 <panto> it's not a simple pointer
May 26 10:25:52 <panto> each malloced area in user-space is an array of scatter gather entries
May 26 10:26:07 <panto> and then you'll have to perform manual cache management
May 26 10:26:23 <Abhishek_> So how to get the underlying scatter-gather entries?
May 26 10:29:38 <Abhishek_> panto: Could you suggest something to start with in this case? Some application where I can see it action?
May 26 10:30:15 <panto> that's what virtio does basically
May 26 10:30:21 <panto> look at that
May 26 10:38:20 <Abhishek_> k, would it be worth to take the implementation to kernel space?
May 26 10:44:21 <praveendath92> vvu: karki: Sorry. I missed.
May 26 10:44:34 <praveendath92> vvu: Are you still around?
May 26 11:03:40 <karki> vvu : when are your exams ending?
May 26 11:05:43 <karki> panto : I can mmap a sysfs entry using bin_attribute s
May 26 11:08:39 <panto> yes
May 26 11:08:46 <karki> panto : I'll be working full time on this today and tomorrow. I hope you are free day after for some discussions on the different components of the probe function in your rproc driver. [I want to accomplish this much by end of wednesday]
May 26 11:09:01 <panto> probably
May 26 11:09:08 <panto> no guarantees, I'm pretty busy myself
May 26 11:09:21 <panto> ping me and if I'm around I'll answer
May 26 11:09:49 <karki> I know. It's okay. I'll try to figure you as much as I can, so that I don't waste much of your time ;)
May 26 11:09:55 <karki> :)
May 26 11:37:04 <vvu> karki: 2morrow
May 26 11:40:11 <karki> :)
May 26 11:40:28 <karki> the last day is always the most frustrating ;)
May 26 11:41:36 <karki> vvu : which subject?
May 26 11:47:41 <praveendath92> vvu: ping again.
May 26 11:47:53 <praveendath92> Network issue.
May 26 11:51:43 <Abhishek_> panto: Will I have to go into the kernel to get the scatter/gather lists, or can it be done from userspace?
May 26 11:53:02 <panto> kernel only
May 26 11:58:27 <Abhishek_> panto: Does that mean your remoteproc driver, or I can write a workaround (maybe an extra function) in the UIO to get me the scatter/gather lists for a large buffer?
May 26 12:07:52 <praveendath92> vvu: Can you check this lsusb log once you are back? https://gist.github.com/praveendath92/7d123d1f15733b23fb37
May 26 12:16:17 <vvu> karki: today distributed systems and tomorrow operating systems
May 26 12:16:41 <vvu> praveendath92: will look 2morrow, a bit busy. need to hack on my n7 to see how the interfaces are. sorry for being out of sync here
May 26 12:16:44 <Abhishek_> good luck vvu :)
May 26 12:16:57 <karki> vvu : atleast you have interesting subjects :)
May 26 12:17:06 <praveendath92> vvu: That's fine/
May 26 12:17:34 <praveendath92> I have enough work to keep me occupied during this time :)
May 26 12:46:04 <vvu> praveendath92: try and enumerate the interfaces you have using libusb
May 26 12:46:09 <vvu> and check each endpoint
May 26 12:46:43 <praveendath92> Will do that.
May 26 12:47:10 <vvu> praveendath92: http://www.dreamincode.net/forums/topic/148707-introduction-to-using-libusb-10/
May 26 12:47:32 <vvu> it is cpp code but it has there a print_dev function that takes a *libusb_dev item i think so and says everything about it
May 26 12:47:35 <praveendath92> Does the log I sent you look fine?
May 26 12:48:10 <vvu> did not fully look through it, but when in doubt use this function, at least helped me a lot last year
May 26 12:48:39 <praveendath92> I will try this now.
May 26 12:49:40 <panto> Abhishek_, it might be possible to extend UIO
May 26 12:49:46 <panto> but it's not going to be an easy thing
May 26 12:51:44 <Abhishek_> panto: as in implementation of cache coherency as well?
May 26 12:52:37 <panto> yeah
May 26 12:52:54 <panto> I doubt it makes much sense at this point
May 26 12:53:02 <panto> just go on with your app at 25MHz
May 26 12:53:14 <Abhishek_> Ok
May 26 12:56:33 <Abhishek_> But I would like to come back and improve it at some point
May 26 12:56:43 <panto> certainly
May 26 12:57:01 <panto> I still think we should do remote proc at some point
May 26 12:57:22 <panto> so structure your application in such a way that this might be possible
May 26 12:57:30 <panto> and when we have time we can go back
May 26 12:58:17 <Abhishek_> Can it be done through mmap?
May 26 12:58:32 <panto> we'll see :)
May 26 12:58:41 <panto> focus on the next task at hand
May 26 12:59:06 <panto> you always have something next to do
May 26 13:00:03 <Abhishek_> Okay. Would it be a good idea to bring it up in Wednesday's meeting? (ds2, mranostay)
May 26 13:15:42 <karki> panto : Is there some way I can simulate device_create_file? In your driver you get the required "struct device *" in the probe function via the "platform_device" structure. Any way I can just make a dummy driver with sysfs not bothering about probe as of now??
May 26 13:16:35 <karki> panto : the first sentence did not come out correctly. but hope you get the idea....
May 26 13:17:59 <panto> struct device *dev = &pdev->dev;
May 26 13:18:19 <panto> you cannot just hack around
May 26 13:18:27 <panto> create a normal platform device
May 26 13:18:56 <karki> okay. I was hoping there was some way to try sysfs before platform.
May 26 13:19:03 <panto> no
May 26 13:19:39 <karki> fine. back to work again :P
May 26 13:21:03 <karki> panto : just that I got comfortable with sysfs, and yet not ready with platform drivers. But I'll try to whip up something by tonite :)
May 26 13:23:28 <panto> it's not a big deal really
May 26 13:23:39 <panto> you get all that almost for free
May 26 13:25:57 <karki> I end up messing things up when I have't really read through well ( I'm a person who cross questions himself 100 times before trying out something that could break stuff :-( )
May 26 13:27:01 * karki remembers the day he shorted a whole block of his school :'(
May 26 13:32:41 <karki> Abhishek_ : I think it would be a good idea to keep your code remote proc friendly. We could end up helping each other. My driver will have sysfs,  mmap functionality which you could use and I could use your code for high speed PRU --> ARM  functionality for PRU Speak :)
May 26 15:28:34 * Abhishek_ adds more NOPs to drop the sample rate to 25 MHz
May 26 15:29:46 <panto> Abhishek_, you can even tweak the PRU frequency if you're feeling lazy :)
May 26 15:30:20 <Abhishek_> cool, would be a good idea to bring down the sample rate more
May 26 15:30:49 <Abhishek_> I was going to compile different firmware for [100, 50, 25, 10, 5, 1, 0.5] MHz
May 26 15:31:08 <Abhishek_> wondered how many NOPs I could insert.
May 26 15:31:09 <panto> single function device :)
May 26 15:31:39 <panto> if you can do that on runtime, it's a very elegant solution
May 26 15:32:03 <Abhishek_> panto: Can using the timer on the PRU lead up to something?
May 26 15:32:04 <panto> you can do really accurate frequencies
May 26 15:32:18 <panto> not at such high rates
May 26 15:35:57 <karki> could some one explain why my BBB (192.168.7.2 )refuses to connect to the internet. I'm able to ssh to it via my comp (192.168.7.9). gateway (192.168.7.1 ) and mask  are set properly. but even ping to the default gateway fails!
May 26 15:36:06 <Abhishek_> iptables?
May 26 15:37:08 <karki> no. directly connected to the network via ethernet
May 26 15:47:08 <Abhishek_> I don't know how to do it in this case, but I configured my BBB to share the PC's internet via the same USB cable using iptables.
May 26 15:51:21 <karki> This is something I have never faced before. I'm quite sure my network settings is correct....
May 26 15:52:50 <Abhishek_> does your PC ping the gateway when configured with the same settings?
May 26 15:56:10 <karki> yes
May 26 15:58:57 <karki> I'm talking on IRC, so I believe that this pc is making it through the default gateway ;)
May 26 15:59:40 <karki> Abhishek_ : even the route command gives me expected and comparable results for both PC and BBB.
May 26 15:59:58 <karki> never had this problem before :/
May 26 16:07:29 <Abhishek_> panto: Reducing the sample rate to 25 MHz gives me a *very* narrow margin, interrupts seem to arrive at the right time but how can I be sure that data hasn't been overwritten while memcpying and all samples are intact?
May 26 16:08:50 <Abhishek_> memcpy takes me 150ms while data arrives at 160ms intervals
May 26 16:10:54 <panto> increase the buffer size then
May 26 16:11:15 <panto> and that what your overflow detection method is there for
May 26 16:11:46 <Abhishek_> The byte counter is off by 8388608 bytes
May 26 16:11:57 <Abhishek_> I suppose I have it then
May 26 16:12:31 <panto> that where you can use external function generators
May 26 16:12:43 <panto> feed the pins some kind of regular input waveform
May 26 16:12:54 <panto> and have some code that verifies it's valid
May 26 16:14:01 <Abhishek_> hmm, maybe I could do something in my PRU firmware to insert a count instead, and then check the pattern on reception
May 26 16:14:12 <panto> that would do too
May 26 16:14:27 <vvu> karki: 21 page final exam for distributed systems, call that interesting topic?
May 26 16:15:00 <karki> vvu : I said the topic is, not the exam ;)
May 26 16:15:18 <vvu> they go glued together
May 26 16:32:15 <Abhishek_> mranostay: If you've seen the previous messages, I am falling short by around 10ms between interrupt and memcpy when I bring the rate down
May 26 16:44:41 * karki thinks it is best to configure iptable on his PC
May 26 17:25:24 <vvu> praveendath92: so you asked last time what about the control transfer right ?
May 26 17:25:42 <praveendath92> Yep.
May 26 17:25:49 <vvu> ok https://gist.github.com/praveendath92/9641145#file-simplectrl-modified-c-L145
May 26 17:26:00 <vvu> look there it uses the handle to send things to
May 26 17:26:11 <praveendath92> I didn't find a control end with that libusb code you sent.
May 26 17:26:25 <vvu> so you do a request type, value and stuff like that. you do not need an endpoint for it
May 26 17:26:44 <praveendath92> I just figured that a while ago.
May 26 17:27:01 <vvu> the same should work in the kernel as well
May 26 17:27:04 <praveendath92> http://libusb.sourceforge.net/api-1.0/group__syncio.html#gadb11f7a761bd12fc77a07f4568d56f38
May 26 17:27:18 <praveendath92> I was out for a while and just back.
May 26 17:27:29 <vvu> yep
May 26 17:27:42 <praveendath92> Looking at how to do this in kernel module now.
May 26 17:27:52 <praveendath92> av500: You around?
May 26 17:28:18 <vvu> praveendath92: https://www.kernel.org/doc/htmldocs/usb/API-usb-control-msg.html
May 26 17:28:41 <vvu> the link i ave you in the email about the led example has control transfer in it
May 26 17:29:11 <praveendath92> Wow. That's awesome.
May 26 17:29:49 <praveendath92> I mean this new link.
May 26 17:30:23 <praveendath92> I will look at that too.
May 26 17:31:54 <vvu> yep, just do it as greg does it there, expose some sysfs so you can change to adk from userspace just to have this set up
May 26 17:34:04 <vvu> any other issues ?
May 26 17:34:29 <praveendath92> About exposing it to userspace for setting to adk mode,
May 26 17:34:37 <vvu> also do you have some documentation about adk mode ?
May 26 17:34:45 <vvu> like what the values in the ctl transfer mean /
May 26 17:35:17 <praveendath92> I'm think that I will just send the control commands in the probe function and release the interface so, it will attach with new pid later.
May 26 17:35:39 <vvu> i think you should have the same driver for both modes
May 26 17:35:42 <vvu> adk and non adk
May 26 17:35:51 <praveendath92> Nope. Nothing in particular. Just the official adk and aoa page.
May 26 17:35:58 <praveendath92> Yes. yes.
May 26 17:36:11 <vvu> because you can declare multiple vid/pid(s)
May 26 17:36:20 <praveendath92> The same probe function checks if the connection is in adk mode already.
May 26 17:36:24 <vvu> and just handle them in the probe function
May 26 17:36:25 <vvu> yep
May 26 17:36:53 <praveendath92> If not, set it - this is just a few cntrl transfers as we have seen.
May 26 17:37:10 <praveendath92> And once it goes to adk-mode, a new story starts.
May 26 17:37:38 <praveendath92> Sorry, I have to ping even for very basic stuff.
May 26 17:37:38 <vvu> ok we should have really robust the change to adk code
May 26 17:37:44 <vvu> np
May 26 17:38:03 <vvu> anyway from next week i will move to TI office in Munich so I will be around all day in front of the pc
May 26 17:38:19 <praveendath92> That's nice.
May 26 17:38:23 <praveendath92> :)
May 26 17:38:28 <Abhishek_> :)
May 26 17:38:51 <praveendath92> How is your prep. going? vvu
May 26 17:38:51 <vvu> we should find out what those values mean
May 26 17:38:56 <vvu> prep regarding ?
May 26 17:39:11 <praveendath92> exam.
May 26 17:39:22 <praveendath92> You have the last one tomorrow. Don't you?
May 26 17:39:26 <vvu> yep
May 26 17:39:42 <vvu> need to start reading about memory management, pages, page tables and stuffz like that
May 26 17:39:57 <praveendath92> I never remembered my exams so well ;-)
May 26 17:40:20 <vvu> but until 2morrow 2PM there are 3 more days, tonight, all nighter and 2morrow morning
May 26 17:40:25 <praveendath92> Oh. Sounds like interesting stuff to me.
May 26 17:40:43 <praveendath92> Haha.
May 26 17:40:59 <praveendath92> Engineer
May 26 17:41:02 <praveendath92> talk
May 26 17:41:06 <praveendath92> ;)
May 26 17:41:44 <vvu> after i finish my exam need to start packing my room to move it :)
May 26 17:41:55 * vvu needs to take all his beagles in a small trip 
May 26 17:42:18 <praveendath92> That's like the most boring job.
May 26 17:42:20 <praveendath92> Packing :/
May 26 17:43:15 <vvu> from next week i will help you test some more
May 26 17:43:40 <vvu> now i'm working on an ARM chromebook don't even have linux headers for it installed
May 26 17:44:50 <praveendath92> Sure :)
May 26 17:46:08 <praveendath92> I may not be available for most of next week but after that all the time.
May 26 17:47:30 <vvu> anybody here has a clue how to install kernel headers that are not available via apt-get install ?
May 26 17:48:26 <karki> copy paste ;)
May 26 17:48:58 <vvu> don't really wanna screw up with the kernel on the chromebook
May 26 17:49:23 <karki> atleast someone has a chromebook :'(
May 26 17:49:36 <karki> vvu what hacking do you plan to do on the CB?
May 26 17:50:09 <vvu> just to test praveendath92 kernel module
May 26 17:50:12 <vvu> nothing much
May 26 17:50:20 <vvu> too slow for some major league hacking
May 26 17:50:42 <vvu> i mainly do all my work on a vps somewhere at digitalocean but that i cannot test there
May 26 19:37:23 <Abhishek_> panto: Charles Steinkuehler just gave me the idea of "isolating" a chunk of memory at boot time.
**** ENDING LOGGING AT Tue May 27 02:59:58 2014