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Tue, 17 Sep 2019 09:38:30 +0000 (UTC) Subject: Re: [PATCH 4/8] drm/ttm: factor out ttm_bo_mmap_vma_setup To: Gerd Hoffmann Cc: David Airlie , Daniel Vetter , open list , dri-devel@lists.freedesktop.org, Huang Rui , Christian Koenig References: <20190913122908.784-1-kraxel@redhat.com> <20190913122908.784-5-kraxel@redhat.com> <88d5a253-ef9e-c998-6353-5ba8680129f2@suse.de> <20190917083425.kwwqyn463gn3mghf@sirius.home.kraxel.org> From: Thomas Zimmermann Openpgp: preference=signencrypt Autocrypt: addr=tzimmermann@suse.de; keydata= xsBNBFs50uABCADEHPidWt974CaxBVbrIBwqcq/WURinJ3+2WlIrKWspiP83vfZKaXhFYsdg XH47fDVbPPj+d6tQrw5lPQCyqjwrCPYnq3WlIBnGPJ4/jreTL6V+qfKRDlGLWFjZcsrPJGE0 BeB5BbqP5erN1qylK9i3gPoQjXGhpBpQYwRrEyQyjuvk+Ev0K1Jc5tVDeJAuau3TGNgah4Yc hdHm3bkPjz9EErV85RwvImQ1dptvx6s7xzwXTgGAsaYZsL8WCwDaTuqFa1d1jjlaxg6+tZsB 9GluwvIhSezPgnEmimZDkGnZRRSFiGP8yjqTjjWuf0bSj5rUnTGiyLyRZRNGcXmu6hjlABEB AAHNKFRob21hcyBaaW1tZXJtYW5uIDx0emltbWVybWFubkBzdXNlLmNvbT7CwJQEEwEIAD4W IQRyF/usjOnPY0ShaOVoDcEdUwt6IwUCWznTtgIbAwUJA8JnAAULCQgHAgYVCgkICwIEFgID AQIeAQIXgAAKCRBoDcEdUwt6I7D7CACBK42XW+7mCiK8ioXMEy1NzGbXC51RzGea8N83oEJS 1KVUtQxrkDxgrW/WLSl/TfqHFsJpdEFOv1XubWbleun3uKPy0e5vZCd5UjZPkeNjnqfCYTDy hVVsdOuFbtWDppJyJrThLqr9AgSFmoCNNUt1SVpYEEOLNE6C32BhlnSq21VLC+YXTgO/ZHTa YXkq54hHj63jwrcjkBSCkXLh37kHeqnl++GHpN+3R+o3w2OpwHAlvVjdKPT27v1tVkiydsFG 65Vd0n3m/ft+IOrGgxQM1C20uqKvsZGB4r3OGR50ekAybO7sjEJJ1Obl4ge/6RRqcvKz4LMb tGs85D6tPIeFzsBNBFs50uABCADGJj+DP1fk+UWOWrf4O61HTbC4Vr9QD2K4fUUHnzg2B6zU R1BPXqLGG0+lzK8kfYU/F5RjmEcClsIkAaFkg4kzKP14tvY1J5+AV3yNqcdg018HNtiyrSwI E0Yz/qm1Ot2NMZ0DdvVBg22IMsiudQ1tx9CH9mtyTbIXgACvl3PW2o9CxiHPE/bohFhwZwh/ kXYYAE51lhinQ3oFEeQZA3w4OTvxSEspiQR8dg8qJJb+YOAc5IKk6sJmmM7JfFMWSr22satM 23oQ3WvJb4RV6HTRTAIEyyZS7g2DhiytgMG60t0qdABG5KXSQW+OKlZRpuWwKWaLh3if/p/u 69dvpanbABEBAAHCwHwEGAEIACYWIQRyF/usjOnPY0ShaOVoDcEdUwt6IwUCWznS4AIbDAUJ A8JnAAAKCRBoDcEdUwt6I6X3CACJ8D+TpXBCqJE5xwog08+Dp8uBpx0T9n1wE0GQisZruACW NofYn8PTX9k4wmegDLwt7YQDdKxQ4+eTfZeLNQqWg6OCftH5Kx7sjWnJ09tOgniVdROzWJ7c VJ/i0okazncsJ+nq48UYvRGE1Swh3A4QRIyphWX4OADOBmTFl9ZYNPnh23eaC9WrNvFr7yP7 iGjMlfEW8l6Lda//EC5VpXVNza0xeae0zFNst2R9pn+bLkihwDLWxOIyifGRxTqNxoS4I1aw VhxPSVztPMSpIA/sOr/N/p6JrBLn+gui2K6mP7bGb8hF+szfArYqz3T1rv1VzUWAJf5Wre5U iNx9uqqx Message-ID: <8b8ce387-1b3c-0a9c-3aaf-6294b3b81018@suse.de> Date: Tue, 17 Sep 2019 11:38:25 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20190917083425.kwwqyn463gn3mghf@sirius.home.kraxel.org> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="xcBYZojvDfoFex0FuyRwVGgUIB7FAb0EG" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --xcBYZojvDfoFex0FuyRwVGgUIB7FAb0EG Content-Type: multipart/mixed; boundary="z8LzN3XfT59kzP8u0OVSCtdI40idw3XEd"; protected-headers="v1" From: Thomas Zimmermann To: Gerd Hoffmann Cc: David Airlie , Daniel Vetter , open list , dri-devel@lists.freedesktop.org, Huang Rui , Christian Koenig Message-ID: <8b8ce387-1b3c-0a9c-3aaf-6294b3b81018@suse.de> Subject: Re: [PATCH 4/8] drm/ttm: factor out ttm_bo_mmap_vma_setup References: <20190913122908.784-1-kraxel@redhat.com> <20190913122908.784-5-kraxel@redhat.com> <88d5a253-ef9e-c998-6353-5ba8680129f2@suse.de> <20190917083425.kwwqyn463gn3mghf@sirius.home.kraxel.org> In-Reply-To: <20190917083425.kwwqyn463gn3mghf@sirius.home.kraxel.org> --z8LzN3XfT59kzP8u0OVSCtdI40idw3XEd Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable Hi Gerd Am 17.09.19 um 10:34 schrieb Gerd Hoffmann: > On Fri, Sep 13, 2019 at 03:05:34PM +0200, Thomas Zimmermann wrote: >=20 >>> +void ttm_bo_mmap_vma_setup(struct ttm_buffer_object *bo, struct vm_a= rea_struct *vma) >>> +{ >>> + vma->vm_ops =3D &ttm_bo_vm_ops; >>> + >>> + /* >>> + * Note: We're transferring the bo reference to >>> + * vma->vm_private_data here. >>> + */ >>> + >>> + vma->vm_private_data =3D bo; >>> + >>> + /* >>> + * We'd like to use VM_PFNMAP on shared mappings, where >>> + * (vma->vm_flags & VM_SHARED) !=3D 0, for performance reasons, >>> + * but for some reason VM_PFNMAP + x86 PAT + write-combine is very >>> + * bad for performance. Until that has been sorted out, use >>> + * VM_MIXEDMAP on all mappings. See freedesktop.org bug #75719 >>> + */ >>> + vma->vm_flags |=3D VM_MIXEDMAP; >>> + vma->vm_flags |=3D VM_IO | VM_DONTEXPAND | VM_DONTDUMP; >>> +} >>> +EXPORT_SYMBOL(ttm_bo_mmap_vma_setup); >> >> To me, this function looks like an internal helper that should rather >> remain internal. >=20 > Well, I'm moving that to a helper exactly to avoid drm gem ttm helpers > messing with ttm internals. To not them initialize vm_flags for > example, and to avoid exporting ttm_bo_vm_ops. Also to make sure ttm b= o > vma's are initialized the same way no matter which code path was taken > to mmap the object. It may not be worth blocking on this, so Acked-by: Thomas Zimmermann But I still think it's not a good interface because it exposes internal details. Please consider another idea: how about splitting off the ttm_bo_get() and vma-flags setup of ttm_fbdev_mmap() into a separate function, like th= is: void ttm_bo_mmap_refed(vma, bo) { ttm_bo_get(bo) ttm_bo_mmap_vma_setup(vma); } EXPORT_SYMBOL(ttm_bo_mmap_refed) int ttm_fbdev_mmap(vma, bo) { if (vma->vm_pgoff !=3D 0) return -EACCES; ttm_bo_mmap_refed(vma, bo); return 0; } That would allow to keep _vma_setup() an internal function. ttm_fbdev_mmap() sounds like it is only for fbdev and the only user is amdgpu. Can it be moved out of ttm entirely? Best regards Thomas >> As mentioned in my reply to patch 5, maybe re-using >> ttm_fbdev_mmap() could help. >=20 > No, the check in that function prevents that from working. >=20 > cheers, > Gerd >=20 > _______________________________________________ > dri-devel mailing list > dri-devel@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/dri-devel >=20 --=20 Thomas Zimmermann Graphics Driver Developer SUSE Linux GmbH, Maxfeldstrasse 5, 90409 Nuernberg, Germany GF: Felix Imend=C3=B6rffer, Mary Higgins, Sri Rasiah HRB 21284 (AG N=C3=BCrnberg) --z8LzN3XfT59kzP8u0OVSCtdI40idw3XEd-- --xcBYZojvDfoFex0FuyRwVGgUIB7FAb0EG Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEchf7rIzpz2NEoWjlaA3BHVMLeiMFAl2AqZEACgkQaA3BHVML eiPJ0ggAnM+WlLYkjAcYW6bwUEv+i+YP7J0X/Ffdu3OiWGM4+Mbh71BejKrlbmfG mKrWR2TBAu/UZTctmqwKNwP/yjmc7d/pjfcGUpKw17aDCwwT6ZYr2PEjgi1yOyym wpYfG/yldlsvbutl8PfNZFlmS5QLyaeJeG/q4l9x7Fe83loNIa62zSW8RhU2Ar0U sNgG+/gU7UL2VPxfhWiIDznB9NL+oCZD/Ec4PWU/jXj5/mQT/dfHYAU3RtreDHcB PzRG4T8fvVHnoYcjuhE2vUVgKPlEc6w8a6G6syRpeydwAr/T3sJgE9SzyIswbTqG rugdli0jsXAQhqQ4s+xuVxDuxpIl0w== =jKnm -----END PGP SIGNATURE----- --xcBYZojvDfoFex0FuyRwVGgUIB7FAb0EG--