From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dinh Nguyen Subject: RE: [PATCH 1/2] usb: dwc2: Option to disable dma descriptor mode Date: Tue, 6 May 2014 14:52:29 -0500 Message-ID: <1399405949.17981.0.camel@linux-builds1> References: <1399328585-30949-1-git-send-email-dinguyen@altera.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-usb-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Paul Zimmerman Cc: "robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org" , "pawel.moll-5wv7dgnIgG8@public.gmane.org" , "mark.rutland-5wv7dgnIgG8@public.gmane.org" , "ijc+devicetree-KcIKpvwj1kUDXYZnReoRVg@public.gmane.org" , "galak-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org" , "dinh.linux-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org" , "devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "linux-usb-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" List-Id: devicetree@vger.kernel.org On Tue, 2014-05-06 at 18:21 +0000, Paul Zimmerman wrote: > > From: dinguyen-EIB2kfCEclfQT0dZR+AlfA@public.gmane.org [mailto:dinguyen-EIB2kfCEclfQT0dZR+AlfA@public.gmane.org] > > Sent: Monday, May 05, 2014 3:23 PM > > > > Even though the IP supports Descriptor DMA mode, it does not support SPLIT > > transactions in this mode. Since the driver can get the Descriptor DMA mode > > support from hardware, the driver in its currently form cannot fully support > > LS/FS devices connected to a HS Hub when Descriptor DMA mode is enabled in the > > driver. Thus, we give the option to disable Descriptor DMA from device tree. > > Hi Dinh, > > Instead of this patch, how about if we make the driver default to buffer > DMA mode instead, and if anyone wants to use descriptor DMA mode, they > can add a DT property for that? I don't think anyone will want that, > since as you say it doesn't fully support LS/FS devices in that mode. Yes, I think that's a good idea. Let me spin up a patchset to do that. Dinh > > The driver originally worked like that. I guess the default got changed by > one of Matthijs' patches, and I didn't notice it. > -- 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