On Wed, Apr 07, 2010 at 11:55:19AM -0400, Alan Stern wrote:
On Wed, 7 Apr 2010, Greg KH wrote:
Alan, any objection to just using usb_buffer_alloc() for every driver? Or is that too much overhead?
I don't know what the overhead is. But usb_buffer_alloc() requires the caller to keep track of the buffer's DMA address, so it's not a simple plug-in replacement. In addition, the consistent memory that usb_buffer_alloc() provides is a scarce resource on some platforms.
Writing new functions is the way to go.
Ok, I'll write some dummies for usb_malloc() and usb_zalloc() which will just call kmalloc() with GFP_DMA32 for now. And while at it, usb_alloc_buffer() will be renamed to usb_alloc_consistent(). Then I'll try to clean up all existing drivers to use this new interface and follow the changes.
In a next step, we should fine-tune when GFP_DMA32 is really needed. And I'll leave all occurances of usb_alloc_consistent() as they are now.
Does that sound ok?
Thanks, Daniel