From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755354AbdLOLkh (ORCPT ); Fri, 15 Dec 2017 06:40:37 -0500 Received: from mail-wm0-f65.google.com ([74.125.82.65]:43864 "EHLO mail-wm0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754344AbdLOLka (ORCPT ); Fri, 15 Dec 2017 06:40:30 -0500 X-Google-Smtp-Source: ACJfBotSLHX/C31cAcYLlE9arUMfzt4fNrOjrQZ5uKrvZvtaS0/LPNsFG7h+pkjgukzYnfN71J6+Pg== Date: Fri, 15 Dec 2017 11:40:25 +0000 From: Daniel Thompson To: Robert Jarzmik Cc: Lee Jones , Jingoo Han , Bartlomiej Zolnierkiewicz , linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 1/3] backlight: tdo24m: fix the spi cs between transfers Message-ID: <20171215114025.4nmuz44xdecpzqt3@oak.lan> References: <20171013194250.9001-1-robert.jarzmik@free.fr> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20171013194250.9001-1-robert.jarzmik@free.fr> User-Agent: NeoMutt/20170113 (1.7.2) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Oct 13, 2017 at 09:42:47PM +0200, Robert Jarzmik wrote: > 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 Didn't I already ack this one? Daniel. > --- > Since v1: added 2 other panels > --- > 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, > }; > > -- > 2.11.0 >