Re: gadget file storage with variable maxpacket
Alan Stern <[email protected]>
| Newsgroups | gmane.linux.usb.devel |
|---|---|
| Message-ID | <[email protected]> |
On Mon, 19 Nov 2007, ilya wrote: > > We can fix the problem easily enough. Just take out the code in > > do_read() and do_write() that handles partial pages, and let the VFS or > > block layer worry about reorganizing the data. > > works like a charm; interesting enough, i've tried this before > but ended up crashing my system so i figured that code > was necessary. so why do you do all this page/block alignment > in the first place if VFS can take care of it? Well, in the first place it isn't really page/block alignment. (That is, it doesn't involve moving data so that the start address lies on a page boundary.) It's just reducing the size of a usb_request so that any additional data will automatically be aligned with no special effort. So this was nothing more than a slight optimization. It may not be worthwhile in the end -- if VFS is going to copy the data into block-cache pages anyway then the initial alignment won't matter. In fact, I don't know whether this partial-page stuff actually helps at all. So I don't mind getting rid of it. Alan Stern ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ [email protected] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel