> -----Original Message----- > From: David Brownell [mailto:[EMAIL PROTECTED] > Sent: Friday, April 20, 2007 12:53 PM > To: Li Yang-r58472 > Cc: linux-usb-devel@lists.sourceforge.net; [EMAIL PROTECTED]; Schmid > Bruce-R62923 > Subject: Re: [linux-usb-devel] [PATCH 1/3]USB: add Freescale high-speed USB > SOC > device controller driver > > On Thursday 19 April 2007 8:56 pm, Li Yang-r58472 wrote: > > > > > > > On Thursday 19 April 2007 2:53 am, Li Yang wrote: > > > > > > +static void *fsl_alloc_buffer(struct usb_ep *_ep, unsigned bytes, > > > > > > + dma_addr_t *dma, gfp_t gfp_flags) > > > > > > +{... > > > > > > +} > > > > > > > > > > You still need to fix this to use dma_alloc_coherent(), and its > > > > > sibling function to use dma_free_coherent(). > > > > > > > > > > This particular code assumes !CONFIG_NOT_COHERENT_CACHE ... which > > > > > ISTR you've said is not true on all the relevant PPC platforms, and > > > > > is certainly not true on the versions found (already?) in Freescale > > > > > ARM products. > > > > > > > > This buffer is synced using dma_sync_single_*/dma_(un)map_single when > > > > the request is queued and when the transmission is complete. To > > > > > > No. See <linux/usb_gadget.h> for the definition of usb_ep_alloc_buffer(); > > > it says explicitly that such mapping calls are not required. > > > > > > The only portable way to guarantee that is to allocate coherent memory. > > > > Then I can remove the dma_sync_single calls from ep_queue() and done()? > > Not a good idea. There are two ways that a DMA address gets > provided to the lower level code: (a) coherent buffer allocation, > as above, and (b) mapping done by driver, and re-used. The former > doesn't need dma_sync_single(). The latter does.
Do you mean that the buf of a usb_request could be allocated other than calling usb_ep_alloc_buffer()? If not, the buf would be guaranteed to be coherent buffer. And will usb_ep_alloc_buffer() be used to allocate buffer other than buffer to be queued with ep_queue()? I mean if usb_ep_alloc_buffer() is required and only used in allocating buffer to be processed by ep_queue() and done(). We can choose to use one of the ways you mentioned above, not both. In this case, I preferred to choose the second way for better performance. - Leo ------------------------------------------------------------------------- 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/ _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
