From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thierry Reding Subject: Re: [PATCH v2 27/27] drm/tegra: Add Tegra114 gr2d support Date: Mon, 14 Oct 2013 16:00:11 +0200 Message-ID: <20131014140010.GC16302@ulmo.nvidia.com> References: <1381134884-5816-1-git-send-email-treding@nvidia.com> <1381134884-5816-28-git-send-email-treding@nvidia.com> <52587F2D.9070007@wwwdotorg.org> <525B880A.7090802@nvidia.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="raC6veAxrt5nqIoY" Return-path: Content-Disposition: inline In-Reply-To: <525B880A.7090802-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org> Sender: linux-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Terje =?utf-8?Q?Bergstr=C3=B6m?= Cc: Stephen Warren , "dri-devel-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org" , "linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" List-Id: devicetree@vger.kernel.org --raC6veAxrt5nqIoY Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Oct 14, 2013 at 08:58:34AM +0300, Terje Bergstr=C3=B6m wrote: > On 12.10.2013 01:43, Stephen Warren wrote: > > On 10/07/2013 02:34 AM, Thierry Reding wrote: > >> The gr2d hardware in Tegra114 is compatible with that of Tegra20 and > >> Tegra30. No functionaly changes are required. > > Similarly here, if the HW is 100% backwards-compatible, there's no need > > to add compatible values to the driver. >=20 > We've used this mechanism for attaching a per-hw-version data structure > in match table to accomodate differences in how the hardware is power > gated, reset, booted, some per-soc performance related changes etc. It's > also used in staging features for new chips, such as disabling power > features when they're not working/verified yet. >=20 > Upstream driver is not yet in a state where that is relevant. >=20 > With this, would we still be able to do that with match table? It sounds > like we could, because we can still (even with multiple compatible > properties) add separate entries in match table and I guess the > compatible properties matched in order. Yes, as long as the device tree files includes the most specific value in the compatible this should still be possible. So we'd have this: gr2d@54140000 { compatible =3D "nvida,tegra114-gr2d", "nvidia,tegra20-gr2d"; ... }; and the driver will match on "nvidia,tegra20-gr2d" if the more specific "nvidia,tegra114-gr2d" is not there. When the driver is updated to support Tegra114 specific functionality, then a more specific entry can be added to the compatible table to handle it. Thierry --raC6veAxrt5nqIoY Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.22 (GNU/Linux) iQIcBAEBAgAGBQJSW/jqAAoJEN0jrNd/PrOhbH4QALU3En3mTdoarh9KS6uc9tXo +EzQPnugO8f4/5CdYHk8/2Zy/VR0wIROG8HK4kMGn8MYocs5AF09FqeCbNLTvNCK KGd//Bp8eTIw7q4OHczdmK1obx939KdQPwMc/Z88kqfGSrk4qeXkU3PTiYjp38MB rqLwzaOmo7aPayNjs0C2cbpmqa277mbDvgvYZwI3G5hSR+SVCqdnXRRRlsykImre usEtC/wx/7x0cVNaNaKQTl56djIfkb4NXbvxT506kZgLGKwtCFR4q2KryeHX0Jg2 RMI7fzaXPWKjEAxnf3pIP57accESv00LXeliE4xpT5oThn5uhPwS12AqkJ0ANr8v LvtwUkWVKXFUyQpYTuogX+0y68c+SkAP5Jud3DMSF8wrdwDdh6e2PGcMaCoDig1c 4KNhBe/EaHMjUyVvapP+rm8/NV54SW9ZKsOQZemsB8J9SyOpJC3qj37DemaTeGp3 Zu+DOYFYWoi1++dO8gjkdjfE9+3k4rG0swJRg2uniasZVWFU5S/rggIjpdIuHQrI sjApAQNWENyfcN6Mnn1wHwwX8/4A7XhibqZyeY3IJYVOa+Oas6fEmcyrzYUUzGCS bKtfBr+dI4gdPey2RxKeQzKNo/KaGHzxXj++lTecq0q0ZBzUOkpUU+hZjDjDu9Hb x28+9JUT/B9CAmatFI7S =aj9q -----END PGP SIGNATURE----- --raC6veAxrt5nqIoY--