From patchwork Thu Dec 28 08:27:41 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Robert Jarzmik X-Patchwork-Id: 10134465 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 83F1E60318 for ; Thu, 28 Dec 2017 08:28:05 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 6A8E02B846 for ; Thu, 28 Dec 2017 08:28:05 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 5EF372C33A; Thu, 28 Dec 2017 08:28:05 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,FREEMAIL_FROM, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 4C1A32B846 for ; Thu, 28 Dec 2017 08:28:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751556AbdL1I2D (ORCPT ); Thu, 28 Dec 2017 03:28:03 -0500 Received: from smtp08.smtpout.orange.fr ([80.12.242.130]:59452 "EHLO smtp.smtpout.orange.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751458AbdL1I2C (ORCPT ); Thu, 28 Dec 2017 03:28:02 -0500 Received: from belgarion.home ([86.201.132.185]) by mwinf5d15 with ME id rLTm1w00D409fna03LTwKP; Thu, 28 Dec 2017 09:28:01 +0100 X-ME-Helo: belgarion.home X-ME-Auth: amFyem1pay5yb2JlcnRAb3JhbmdlLmZy X-ME-Date: Thu, 28 Dec 2017 09:28:01 +0100 X-ME-IP: 86.201.132.185 From: Robert Jarzmik To: Lee Jones , Daniel Thompson , Jingoo Han , Bartlomiej Zolnierkiewicz Cc: dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org, Robert Jarzmik Subject: [PATCH v3] backlight: tdo24m: fix the spi cs between transfers Date: Thu, 28 Dec 2017 09:27:41 +0100 Message-Id: <20171228082742.13415-1-robert.jarzmik@free.fr> X-Mailer: git-send-email 2.11.0 Sender: linux-fbdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fbdev@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Currently the LCD display (TD035S) on the cm-x300 platform is broken and remains blank. The TD0245S specification requires that the chipselect is toggled between commands sent to the panel. This was also the purpose of the former patch of commit f64dcac0b124 ("backlight: tdo24m: ensure chip select changes between transfers"). Unfortunately, the "cs_change" field of a SPI transfer is misleading. Its true meaning is that for a SPI message holding multiple transfers, the chip select is toggled between each transfer, but for the last transfer it remains asserted. In this driver, all the SPI messages contain exactly one transfer, which means that each transfer is the last of its message, and as a consequence the chip select is never toggled. Actually, there was a second bug hidding the first one, hence the problem was not seen until v4.6. This problem was fixed by commit a52db659c79c ("spi: pxa2xx: Fix cs_change management") for PXA based boards. This fix makes the TD035S work again on a cm-x300 board. The same applies to other PXA boards, ie. corgi and tosa. Fixes: a52db659c79c ("spi: pxa2xx: Fix cs_change management") Reported-by: Andrea Adami Signed-off-by: Robert Jarzmik Acked-by: Daniel Thompson --- Since v1: added 2 other panels Since v2: added Daniel's ack --- drivers/video/backlight/corgi_lcd.c | 2 +- drivers/video/backlight/tdo24m.c | 2 +- drivers/video/backlight/tosa_lcd.c | 2 +- 3 files changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/video/backlight/corgi_lcd.c b/drivers/video/backlight/corgi_lcd.c index d7c239ea3d09..f5574060f9c8 100644 --- a/drivers/video/backlight/corgi_lcd.c +++ b/drivers/video/backlight/corgi_lcd.c @@ -177,7 +177,7 @@ static int corgi_ssp_lcdtg_send(struct corgi_lcd *lcd, int adrs, uint8_t data) struct spi_message msg; struct spi_transfer xfer = { .len = 1, - .cs_change = 1, + .cs_change = 0, .tx_buf = lcd->buf, }; diff --git a/drivers/video/backlight/tdo24m.c b/drivers/video/backlight/tdo24m.c index eab1f842f9c0..e4bd63e9db6b 100644 --- a/drivers/video/backlight/tdo24m.c +++ b/drivers/video/backlight/tdo24m.c @@ -369,7 +369,7 @@ static int tdo24m_probe(struct spi_device *spi) spi_message_init(m); - x->cs_change = 1; + x->cs_change = 0; x->tx_buf = &lcd->buf[0]; spi_message_add_tail(x, m); diff --git a/drivers/video/backlight/tosa_lcd.c b/drivers/video/backlight/tosa_lcd.c index 6a41ea92737a..4dc5ee8debeb 100644 --- a/drivers/video/backlight/tosa_lcd.c +++ b/drivers/video/backlight/tosa_lcd.c @@ -49,7 +49,7 @@ static int tosa_tg_send(struct spi_device *spi, int adrs, uint8_t data) struct spi_message msg; struct spi_transfer xfer = { .len = 1, - .cs_change = 1, + .cs_change = 0, .tx_buf = buf, };