From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thierry Reding Subject: Re: [RFC 4/4] drm: Add NVIDIA Tegra support Date: Thu, 12 Apr 2012 15:42:16 +0200 Message-ID: <20120412134216.GB15701@avionic-0098.adnet.avionic-design.de> References: <1334146230-1795-1-git-send-email-thierry.reding@avionic-design.de> <20120411133512.GL4296@phenom.ffwll.local> <20120411141108.GI27337@avionic-0098.adnet.avionic-design.de> <201204111518.41968.arnd@arndb.de> <20120412071816.GA18252@avionic-0098.mockup.avionic-design.de> <025f01cd1887$da56b6e0$8f0424a0$%szyprowski@samsung.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="l76fUT7nc3MelDdI" Return-path: Content-Disposition: inline In-Reply-To: <025f01cd1887$da56b6e0$8f0424a0$%szyprowski-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org> Sender: linux-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Marek Szyprowski Cc: 'Arnd Bergmann' , devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org, 'Daniel Vetter' , 'Joerg Roedel' , dri-devel-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org, 'Jon Mayo' , iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, 'Colin Cross' , linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, 'Hiroshi Doyu' , Tomasz Stanislawski List-Id: dri-devel@lists.freedesktop.org --l76fUT7nc3MelDdI Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable * Marek Szyprowski wrote: > Hi Thierry, >=20 > On Thursday, April 12, 2012 9:18 AM Thierry Reding wrote: > > Also this doesn't yet solve the vmap() problem that is needed for the k= ernel > > virtual mapping. I did try using dma_alloc_writecombine(), but that only > > works for chunks of 2 MB or smaller, unless I use init_consistent_dma_s= ize() > > during board setup, which isn't provided for in a DT setup. I couldn't = find > > a better alternative, but I admit I'm not very familiar with all the VM= APIs. > > Do you have any suggestions on how to solve this? Otherwise I'll try an= d dig > > in some more. >=20 > Yes, I'm aware of this issue I'm currently working on solving it. I hope = to use=20 > standard vmalloc range for all coherent/writecombine allocations and get = rid of > the custom 'consistent_dma' region at all. Does your work aim at removing the 2 MB limitation or at remapping non- contiguous memory to a virtually linear buffer? I have some trouble understanding how removing the 2 MB limit would help, because if all buffers can be allocated contiguously then there wouldn't be any need for the IOMMU, right? Thierry --l76fUT7nc3MelDdI Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.19 (GNU/Linux) iEYEARECAAYFAk+G27gACgkQZ+BJyKLjJp998ACdFuA0NERIMlxCc1SHhNhFmTxU cs4An2uoQh8SglkZlHbV/B4MZ7rF8QKW =+dKM -----END PGP SIGNATURE----- --l76fUT7nc3MelDdI--