From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tomi Valkeinen Subject: Re: [RESEND PATCH 1/2] devicetree: mxsfb: add reset-active property Date: Tue, 12 Jan 2016 15:39:06 +0200 Message-ID: <569501FA.2060304@ti.com> References: <1452594141-26073-1-git-send-email-mans@mansr.com> <5694F51C.7040107@ti.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="Xef7RdBgTfRQcRS1LiGXW07UaemInVVR6" Return-path: In-Reply-To: Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: =?UTF-8?B?TcOlbnMgUnVsbGfDpXJk?= Cc: Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , Jean-Christophe Plagniol-Villard , devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-fbdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: devicetree@vger.kernel.org --Xef7RdBgTfRQcRS1LiGXW07UaemInVVR6 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On 12/01/16 15:10, M=C3=A5ns Rullg=C3=A5rd wrote: >> I don't see any sleeps related to reset in the code. If reset is >> asserted when the display is blanked, is it guaranteed that the reset >> stays asserted long enough until the display is enabled again? >=20 > In the datasheet for the panel I'm dealing with, there's some vague > mention of 10 us (I missed it last time I looked), and my patch indeed > fails to ensure this is met. Other panels will obviously have differen= t > requirements. To handle all cases properly, I suppose a configurable > delay after changing the reset pin should be added. Right. And then you need to ensure the powers are enabled in the right order, the pixel clock is started at the right time (some need pix clock before reset), and so on and so on =3D). > I could also take the lazy way out, pinmux this signal high and leave i= t > at that. I've seen panels that require a reset after powers have been off, or similar, but I hope those are minority. So yes, probably just making sure the reset is not asserted is the most generic and easy way forward. Tomi --Xef7RdBgTfRQcRS1LiGXW07UaemInVVR6 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQIcBAEBCAAGBQJWlQH6AAoJEPo9qoy8lh71sogP/3frrmFZkgzKymU1ki3l0KM4 fG7NlbfLUz+2666JEEyJUb9AEyg4UMqWfVF5O09A1UkKx50lKrNBmee1YpA40SpB uQ+O080o4OpafZ34sOej/eaG00+wwCDh8U8mDMtu5h+ckiEaHD4eZNih5mgaxBA9 ScsQRB7QBSBopePnNv15sB+AjheEeGF9dT9YCy7WrjwQleMnZAEXxRBaeBhXAaHZ WXiK7a5xOZ1nUQCiBMJP9fN+fHIpvCPdPgfZweBc2xyC5RGBKCCL0972Ddhoz3VB ODZEN+TRckBTIJW2RTeYbkwy5LYbcqlxjkqU69XIbpnTWD+iSTGuF1hHiolPR7LX urN2F5Cj4TqOcN9nb6611XzWOaOb6aimU7Wvh84dfqaHRQLsrboB+T2b4KN157t6 319MbXvx/vwRHmNPUx/3Ubk7wosVA5W+WGp+OeClSyP7N+LPHRwRy8mxKBryCIV/ fNk77ny4UFxYfauUFAUcDll8h0QFhbzZ9I6LTtJlC8ad0b/i5Hm5gMdZ04MA9AjH Pgk0VkxvwifNgp7KHpXB+ehqzxo3o897Z0usZJQA+92GGPuE5hTKbOFWjmUfLoK/ kwL5Wf5WSM52i3EUlmfxwZtBg46MDQRBt2Q7XUv7fZdcDrkH+qYEibyDN0Wqevb+ 0jkMi7TvX/ZRD3FXNbZV =vxC0 -----END PGP SIGNATURE----- --Xef7RdBgTfRQcRS1LiGXW07UaemInVVR6-- -- 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