Re: [patch/rfc 2.6.22-rc7] usb/dma doc updates
Oliver Neukum <[email protected]>
| Newsgroups | gmane.linux.usb.devel |
|---|---|
| Message-ID | <[email protected]> |
Am Montag, 2. Juli 2007 schrieb David Brownell: > + Most drivers should *NOT* be using these primitives. On most systems > + the memory returned will be uncached, so it's a bit more expensive to > + access than what kmalloc() returns. This is somewhat hard to understand. If we use this memory as a real working space it makes sense. But if we do a memcpy() into the buffer, why do we care? The data has to hit RAM for DMA to work. So why not do the work at once, at least in the write path? We are as an advantage sure to get memory we can do DMA to. Regards Oliver ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/ _______________________________________________ [email protected] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel