From mboxrd@z Thu Jan 1 00:00:00 1970 From: Felipe Balbi Subject: Re: [PATCH 1/2] usb: dwc2: Option to disable dma descriptor mode Date: Tue, 6 May 2014 20:58:45 -0500 Message-ID: <20140507015845.GB20489@saruman.home> References: <1399328585-30949-1-git-send-email-dinguyen@altera.com> <20140506183630.GA31117@saruman.home> Reply-To: Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="K8nIJk4ghYZn606h" Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-usb-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Paul Zimmerman Cc: "balbi-l0cyMroinI0@public.gmane.org" , "dinguyen-EIB2kfCEclfQT0dZR+AlfA@public.gmane.org" , "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 --K8nIJk4ghYZn606h Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, May 06, 2014 at 08:11:34PM +0000, Paul Zimmerman wrote: > > From: Felipe Balbi [mailto:balbi-l0cyMroinI0@public.gmane.org] > > Sent: Tuesday, May 06, 2014 11:37 AM > >=20 > > On Tue, May 06, 2014 at 06:21:02PM +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 suppor= t SPLIT > > > > transactions in this mode. Since the driver can get the Descriptor = DMA mode > > > > support from hardware, the driver in its currently form cannot full= y support > > > > LS/FS devices connected to a HS Hub when Descriptor DMA mode is ena= bled in the > > > > driver. Thus, we give the option to disable Descriptor DMA from dev= ice tree. > > > > > > Hi Dinh, > > > > > > Instead of this patch, how about if we make the driver default to buf= fer > > > 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. > > > > > > The driver originally worked like that. I guess the default got chang= ed by > > > one of Matthijs' patches, and I didn't notice it. > >=20 > > if this is the case, I guess you could call it a regression - well, it > > _did_ break LS/FS use cases - and still merge it during the -rc cycle. >=20 > Well, the change from Matthijs went in on August 30th last year. So it's > not exactly a recent regression ;) damn :-) alright, then merge window possibly with a stable tag, so it gets backported ? cheers --=20 balbi --K8nIJk4ghYZn606h Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQIcBAEBAgAGBQJTaZNVAAoJEIaOsuA1yqRE9XwQAJrWFxCwHpXwp1KaI3Modprj m5+qXFIkNSoZnrroi3yU6cz1li4jdyJEGosCiBn1JbWkKIZoV6dMDskzFx8BqoQr 2VcAmkSh1I8edDL7Gndxs33kZPpPx7n5NA0jxcsdoMrfB0wJfbg2nR8LBDWbioP5 ARqghCi/SmwD3T/huitrIVvDkYFs62iXW8sCQCadWI/eSiM0po88Qtkona/xQJEu 8H9VJ/Ep+xLAljYUse3QI4wdKRHK8GSttIg2+f/lnz5Wb4uehO+rXHPsnJN7gF6e cCJ61mhnGIbL7l2ud5hApie/sVOO6WLDjDfIymp89zQz/B0vi/V8917lB2MVZfE/ M9wObWFmj5S1Bw27S5xKww7kQZRuxynmTBrZVjt7LluGD0TsnNCccYgWv5BbGY/a +JRw8nIw4l23WFEarYVL7J/Hr/rwZne+/aaJvVftBy13aMgPQ/qpLggI6idpa90h s67nJAMFRxiOC4gqkEhRQJ5tEiYggKInDkFv23VPj4JkkJ0cvDm/9aNtvmdRVq1o QTTYCaqfGK3tg+NOdYJIcPDrDaFCiDB26ZyWKAkx0KqfNqhln5QB2YYFxvkT3FTr ontK+Z0hYvr6QpJouhhKbDAbBg+w9ivj1tFq7pnM5jQY0qCC8l23MHy4DnV2BOM/ qd/1hNjhDft2IbUIjbiy =cuPa -----END PGP SIGNATURE----- --K8nIJk4ghYZn606h-- -- 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