Hi Jon and Ge, I switched my driver code by using kfifo (using code on linux-next), now what I see is: using generic-buffer application, I catch every sample independently by the value of buffer length, is that what you tell me by "Kfifo has a more conventional poll and will fire off userspace whenever any data is in the buffer."? To catch data only when the buffer is full, I must catch a particular signal event in /dev/iio:deviceX? Thanks Denis 2012/9/26 Jonathan Cameron <jic23@xxxxxxxxxxxxxxxxxxxxx>: > On 26/09/12 02:32, Ge Gao wrote: >> >> To use KFIFO, you need Jonanthan's KFIFO poll patch, > > That's in staging-next now and will merge into mainline in the > next merge window (about 1 to 2 weeks time). > >> you probably also >> need a patch from me that fixed the industrial-buffer.c. But that buffer >> is not well tested and is only used by me. > > There are a lot of drivers using kfifo. It's hidden in many of them as they > use it via the industrialio-triggered-buffer helper functions that > deal with the most common use cases. > > With that I count 9 in drivers/iio and 6 in drivers/staging/iio vs 10 > in total for sw_ring most of which will go away once someone has a spare > couple of hours. > > Basically any driver that has come along since we moved to kfifo is the > preferred choice and any that anyone has touched since then. > > >> The original KFIFO does not >> have poll functionality and has some other minor bug. > > If I've missed any patches from you on this (or just forgotten them ;) > please do keep pestering me. > >> >> Ge >> >> >> -----Original Message----- >> From: linux-iio-owner@xxxxxxxxxxxxxxx >> [mailto:linux-iio-owner@xxxxxxxxxxxxxxx] On Behalf Of Denis Ciocca >> Sent: Tuesday, September 25, 2012 2:35 PM >> To: jic23@xxxxxxxxxxxxxxxxxxxxx >> Cc: linux-iio@xxxxxxxxxxxxxxx >> Subject: iio_buffer length >> >> Hi Jon, >> >>> Firstly please confirm you are using a kfifo buffer? >> >> >> No, I use sw-ring. >> >> >>> Swring is deprecated but will do precisely what you are seeing I think. >> >> It uses a half full watershead to decide to signal userspace. If you wait >> till the buffer is full, unless your sampling is very slow you will have >> data coming in before userspace has read the whole buffer out. Hence you >> will loose data. >> >> You are right. I saw exatly what you said. >> >> >>> Kfifo has a more conventional poll and will fire off userspace >>> whenever >> >> any data is in the buffer. Hence kfifo will work for your usecase. I >> would like to have a fill level capable buffer again in the future as they >> are very useful in high speed uses where latency doesn't matter. >> >> Ok, I will change my sw-ring buffer to kfifo! >> >> Thanks, >> Denis >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-iio" in >> the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at >> http://vger.kernel.org/majordomo-info.html >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-iio" in >> the body of a message to majordomo@xxxxxxxxxxxxxxx >> More majordomo info at http://vger.kernel.org/majordomo-info.html >> > -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
