From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932937Ab0DHQ7m (ORCPT ); Thu, 8 Apr 2010 12:59:42 -0400 Received: from iolanthe.rowland.org ([192.131.102.54]:47194 "HELO iolanthe.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S932728Ab0DHQ7i (ORCPT ); Thu, 8 Apr 2010 12:59:38 -0400 Date: Thu, 8 Apr 2010 12:59:38 -0400 (EDT) From: Alan Stern X-X-Sender: stern@iolanthe.rowland.org To: Oliver Neukum cc: Daniel Mack , , Pedro Ribeiro , , Greg KH , , Subject: Re: USB transfer_buffer allocations on 64bit systems In-Reply-To: <201004080812.04419.oliver@neukum.org> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 8 Apr 2010, Oliver Neukum wrote: > Am Mittwoch, 7. April 2010 17:46:17 schrieb Alan Stern: > > Or alternatively, instead of allocating regular memory the routine > > could simply fail. Then the caller would be responsible for checking > > and using regular memory instead of dma-consistent memory. Of course, > > that would put an even larger burden on the caller than just forcing it > > to keep track of what flag to use. > > Then it would be sensible to pass it a filled URB, modify it or return > an error code. That would work, but it doesn't match the way existing drivers use the interface. For example, the audio driver allocates a 16-byte coherent buffer and then uses four bytes from it for each of four different URBs. Alan Stern From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alan Stern Subject: Re: USB transfer_buffer allocations on 64bit systems Date: Thu, 8 Apr 2010 12:59:38 -0400 (EDT) Message-ID: References: <201004080812.04419.oliver@neukum.org> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Return-path: In-Reply-To: <201004080812.04419.oliver-GvhC2dPhHPQdnm+yROfE0A@public.gmane.org> Sender: linux-usb-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Oliver Neukum Cc: Daniel Mack , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Pedro Ribeiro , akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org, Greg KH , alsa-devel-K7yf7f+aM1XWsZ/bQMPhNw@public.gmane.org, linux-usb-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: alsa-devel@alsa-project.org On Thu, 8 Apr 2010, Oliver Neukum wrote: > Am Mittwoch, 7. April 2010 17:46:17 schrieb Alan Stern: > > Or alternatively, instead of allocating regular memory the routine > > could simply fail. Then the caller would be responsible for checking > > and using regular memory instead of dma-consistent memory. Of course, > > that would put an even larger burden on the caller than just forcing it > > to keep track of what flag to use. > > Then it would be sensible to pass it a filled URB, modify it or return > an error code. That would work, but it doesn't match the way existing drivers use the interface. For example, the audio driver allocates a 16-byte coherent buffer and then uses four bytes from it for each of four different URBs. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html