On Wed, 7 Jun 2006 15:40:13 -0700 Greg KH <[EMAIL PROTECTED]> wrote: | On Wed, Jun 07, 2006 at 04:53:33PM -0300, Luiz Fernando N. Capitulino wrote: | > | > Hi Sergei, | > | > On Wed, 07 Jun 2006 21:54:16 +0400 | > Sergei Organov <[EMAIL PROTECTED]> wrote: | > | > | Would it be a welcome contribution if I try to split the "generic" into, | > | say, usb-serial-core and usb-serial-generic, the latter being really | > | tiny at the beginning, and then improve it for speed? I've actually done | > | it (speed improvement for bulk transfers) one time for 2.4.x, but at | > | that time interface to the tty layer was not suitable for high-speed | > | transfers and therefore my code had quite a few ugly kludges and finally | > | I wasn't able to match raw USB bulk speeds anyway. Now, AFAIK, the tty | > | layer interface has been improved and I hope to have better experience. | > | > Yes, it was. | > | > Considering the current design, one thing I'd like to have is the generic | > code completely decoupled from the usbserial module, ie, a real | > usbserial-generic module. | > | > This would also force us to kill the fix_up_generic() function. | > I don't like the way it works, IMHO, it's C black magic, and it | > can lead to trouble. | | How? It works like other kernel functions, if you don't define your own | function pointer, it defaults to the "generic" one.
My theoretical trouble may happen when you're new to the usbserial layer and are hacking a new driver and forget to assign, let's say, open(). Then you run the driver, and realizes that a magical function ran. After some time debugging it, you discover fixup_generic(). Okay, I exaggerated a bit. Maybe it's just a matter of taste. | I created the fix_up_generic() function to make it easier than doing the | check on every test for the different function pointers. One test at | module load time is better than a test for every time write() is called | :) Sure, and that's really good. But I'd check whether it's NULL, if so, I wouldn't load the driver and would print a message, something like "open() not assigned". | > Would be better to have usbserial-generic only exporting the | > generic methods, then driver authors would assign by hand the methods | > he (or she) wants to use (yes, nothing automatic). | | What happens if they don't set up the proper functions? We should | default back to the "generic" ones then, otherwise bad things can | happen. | | Think of it as inheriting from a base C++ class, and it will become more | comfortable :) :) -- Luiz Fernando N. Capitulino _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
