From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752029AbbJKOTv (ORCPT ); Sun, 11 Oct 2015 10:19:51 -0400 Received: from smtp.domeneshop.no ([194.63.252.55]:39887 "EHLO smtp.domeneshop.no" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751282AbbJKOTu (ORCPT ); Sun, 11 Oct 2015 10:19:50 -0400 Subject: Re: [PATCH 1/2] staging: fbtft: add support for ST7789V display controller To: Dennis Menschel , Thomas Petazzoni References: <15d2be7d8dae6c8f7c399478db405479b01b698d.1444159111.git.menschel-d@posteo.de> <5619307D.8080009@tronnes.org> <561A1037.80903@posteo.de> Cc: Greg Kroah-Hartman , linux-kernel@vger.kernel.org, devel@driverdev.osuosl.org From: =?UTF-8?Q?Noralf_Tr=c3=b8nnes?= Message-ID: <561A6FFF.6010603@tronnes.org> Date: Sun, 11 Oct 2015 16:19:43 +0200 User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 MIME-Version: 1.0 In-Reply-To: <561A1037.80903@posteo.de> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Den 11.10.2015 09:31, skrev Dennis Menschel: > Am 10.10.2015 um 17:36 schrieb Noralf Trønnes: >> Den 07.10.2015 22:15, skrev Dennis Menschel: >>> This patch adds support for the Sitronix ST7789V display controller. >>> The controller is intended for small color displays with a resolution >>> of up to 320x240 pixels. >>> >>> Signed-off-by: Dennis Menschel >>> --- ... >> (blank() is used on OLED controllers and set_gamma() will be obsolete with >> display drivers since gamma can be set in init()) ... > Thank you for your detailed explanation about the current state of fbtft > and the future plans for a possible successor framework. As suggested by > you, I'll make the following changes in the next patch: > > - Change the st7789v controller driver to a cberry28 display driver. > - If applicable, use the default fbtft implementation of set_addr_win(). > - Remove the blank() function as it is only intended for OLED displays. I want to expand a bit on blank(), it can be used by all drivers, but all the non-OLED displays I have tried turns off the pixels when it's blanked, so the backlight shines through, making it of no use (no power savings to speak of either). So these displays need the backlight to be turned off during blanking. The main reason blank() isn't implemented in the controller drivers, is that if it's used on a display without backlight control, the display would turn white during blanking. There's a bug in the fbtft backlight implementation that prevents it from turning off backlight on the first fb_blank. Subsequent blanks are ok. I haven't looked into it, because the fbtft backlight implementation should really be handled by the gpio-backlight driver. That's what I've done in my new work. Noralf.