From mboxrd@z Thu Jan 1 00:00:00 1970 From: Maxime Ripard Subject: Re: [PATCH] ARM: dts: sun7i: Add Goodix GT911 nodes for Wexler TAB7200 Date: Tue, 14 Apr 2015 18:32:32 +0200 Message-ID: <20150414163232.GD15807@lukather> References: <1427789897-4085-1-git-send-email-mamlinav@gmail.com> <20150331144338.GG23664@lukather> <20150331221420.3b65d2540c7dbe1d12611e12@gmail.com> <20150402092259.GK23664@lukather> <20150411191816.cdc5ec802b01028eb2913906@gmail.com> <20150413160951.GJ29832@lukather> <20150413220100.8666a3d121fce581ba836fe6@gmail.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="9crTWz/Z+Zyzu20v" Return-path: Content-Disposition: inline In-Reply-To: <20150413220100.8666a3d121fce581ba836fe6-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Aleksei Mamlin Cc: devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org List-Id: devicetree@vger.kernel.org --9crTWz/Z+Zyzu20v Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Apr 13, 2015 at 10:01:00PM +0300, Aleksei Mamlin wrote: > On Mon, 13 Apr 2015 18:09:51 +0200 > Maxime Ripard wrote: >=20 > > On Sat, Apr 11, 2015 at 07:18:16PM +0300, Aleksei Mamlin wrote: > > > On Thu, 2 Apr 2015 11:22:59 +0200 > > > Maxime Ripard wrote: > > >=20 > > > > On Tue, Mar 31, 2015 at 10:14:20PM +0300, Aleksei Mamlin wrote: > > > > > On Tue, 31 Mar 2015 07:43:38 -0700 > > > > > Maxime Ripard wrote: > > > > >=20 > > > > > > Hi, > > > > > >=20 > > > > > > On Tue, Mar 31, 2015 at 11:18:17AM +0300, Aleksei Mamlin wrote: > > > > > > > This patch adds nodes for the Goodix GT911 touchscreen contro= ller found > > > > > > > on the Wexler TAB7200 tablet. Controller uses one of followin= g I2C > > > > > > > addresses: 0x5d or 0x14, so just add two nodes. > > > > > >=20 > > > > > > In which case are these different addresses encountered? Differ= ent > > > > > > revisions of the same board? > > > > > > > > > > According to the datasheet it is a feature of the controller.=20 > > > > > The address(0x5d or 0x14) can be configured using a reset sequenc= e, > > > > > which has not yet been implemented in the driver. > > > >=20 > > > > Which address is set up by the bootloader then? > > > > > > I assume that bootloader(u-boot) didn't sets up any address, but touc= hscreen > > > controller usually uses 0x5d. Sometimes, after hard reset, it uses 0x= 14. > > > For this we need nodes on both adresses. > >=20 > > I'm confused, who changes that address then? > >=20 > > The controller itself? > >=20 > If I understood correctly, when device starts it sets reset pin (PB13) to > high level and int pin(PH21) to low level. After this int pin sets up as > external interrupt. This sequence triggers controller to use 0x5d address. >=20 > After hard reset both pins may be hight level and it triggers controller > to use 0x14 address. >=20 > Please see datasheets at pages 8-10. >=20 > https://drive.google.com/file/d/0BxCVOQS3ZymGdEE0cHI3bnp5WVE > https://drive.google.com/file/d/0BxCVOQS3ZymGbDAzVnZwZ2lOZ1E If so, then the driver should be fixed to handle that power sequence correctly and make sure that the device is using the 0x5d address, whatever the previous state was. Maxime --=20 Maxime Ripard, Free Electrons Embedded Linux, Kernel and Android engineering http://free-electrons.com --9crTWz/Z+Zyzu20v Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQIcBAEBAgAGBQJVLUEgAAoJEBx+YmzsjxAg9xoP/itnxBZrQWgv2+p2EWVxkisG darXo4ZO1id85qnlbVa0irImfUXhYDKyebRpod/gDOAS5yVVj7NKj6WeGmnUFQTE x28ai6BiPkNgXnrngNxZ/4QcaWzO4KwRnoBCred5EroS5NYg0bMXPsOrUvNHKIfP aFe7Y8x4NJ2szzssupjBc8Bz1ySEwjO0JfUsYaHz3Ax8vBXcczy/pLmedFElmDCC 3iyllBKRXtzuXF41ssmIZLGy0jLbCDe8vhLHWJcgvTIHrqpnsbUsEx5FiG6P5Ff7 tL9H25sGIK3a1m2S10MhdN/BkcYsqUjFCVPzyGKjZlxzXeHNf6joR6W3xNcGs3XY kU0YKRdl+3nHDsIZE5NMMTwTw5ce9pC2w0SekIU0fQ4OMk8SDOFHWGFxAZdNKNwK cWqW8aum+TKgTpHA7C7Obe+Gx28y6osEi4hB2hqq0l/2K5Dgv44vmMZZhneF7Xlx yToSCkBl42sP1TqHryZBn8xtmt6KhzeEOEQLw8beFyGYvIxoQs0edRafQgx2wTsq fAcrmYA3OpD0Q8fEOTnA4XxAqcjqYuaahOKPlArlN8FmZBgMY5p4BrMjcMUkOIEr o/wLyiQNct90wZ47aXgfziQtQNASilxyyMWi2DGXSFJUGnJV7+hZpUJ1A2CzF5wg D/SUvsGpMcdFWrXA0BVi =74Ct -----END PGP SIGNATURE----- --9crTWz/Z+Zyzu20v-- -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html