From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AIpwx49KhqSS3M/kk+zVjbWDCpfKa2IVao18sDoK4IKV9k+ctonqbNvXo3302p44CNXomUy7JjhM ARC-Seal: i=1; a=rsa-sha256; t=1523399341; cv=none; d=google.com; s=arc-20160816; b=uS/C92QgINPnzcgcleRUymweG7AAYwhYINQ8cRZycZmFFryzGRZOdu74YXm3q3TZT3 X6EIdOUoWbLF0A5fRCyBxUJSqPwPZmEEI2xRUrHkxtxmLmwmvC3n0LdQCgkSI50/5F3S QDxDsSM644+EThhXMzZ7l26tPCKXgbikCHdULOLXu+DLvoSGGobJ0maBWHBqfdW+bz2e KuI6FXfIDMwgozdOYMCs1H6oNhr2mxXJ8cPQsXEBSu8WmyqhbrtJyUcs645SlYdYLLid 0EObd1UxR9zTFk0oV9j0sYhf+QH10vQ27gx2RA5AVTNLSD+gSBhMGIJQb5jFTGc8vvC2 cRYg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=mime-version:user-agent:references:in-reply-to:message-id:date :subject:cc:to:from:arc-authentication-results; bh=CaTtowvVAZ+XDgPwcWH4QuEeXw57ZPbDGff2pb/e8t8=; b=p6CHPnUk0b6eWxI2qlsHL/irC5s5VVWfB2K6Y+WmJpZKRY5xf0SC90o3D8+YUwn7UB zadZ4m4WC7moWMbZytAyvGzH1TyGuW9M3Fn8dIqsoxjRIW5pB/3ok4EhPByCw6PCufuY GexAXUfsXyqXAKEthYt/+Wg2DajDd1ZP8Z8JYmFU98QFjKiRfxy82ni9qVTAl9srDZN9 aMh/g4dAEw5vpSkQoZChh2wRHOafd6ZdIliG6Ku0utP2tykXevjrNkhA6/PoEs4+u/sg Tv0aVRZD0Le87AIt8BT/4l/IFycNgqZ1DnfKPc1D3yCiHqnvR+LqlC4ulb0QeEH2c3rK GGXg== ARC-Authentication-Results: i=1; mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 90.92.61.202 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org Authentication-Results: mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 90.92.61.202 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Andrea Adami , Robert Jarzmik , Daniel Thompson , Lee Jones , Sasha Levin Subject: [PATCH 4.15 054/168] backlight: tdo24m: Fix the SPI CS between transfers Date: Wed, 11 Apr 2018 00:23:16 +0200 Message-Id: <20180410212802.508966761@linuxfoundation.org> X-Mailer: git-send-email 2.17.0 In-Reply-To: <20180410212800.144079021@linuxfoundation.org> References: <20180410212800.144079021@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-LABELS: =?utf-8?b?IlxcU2VudCI=?= X-GMAIL-THRID: =?utf-8?q?1597399987909827945?= X-GMAIL-MSGID: =?utf-8?q?1597399987909827945?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 4.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Robert Jarzmik [ Upstream commit 2023b0524a6310e9ea80daf085f51c71bff9289f ] 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 Signed-off-by: Lee Jones Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- 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(-) --- 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 c struct spi_message msg; struct spi_transfer xfer = { .len = 1, - .cs_change = 1, + .cs_change = 0, .tx_buf = lcd->buf, }; --- a/drivers/video/backlight/tdo24m.c +++ b/drivers/video/backlight/tdo24m.c @@ -369,7 +369,7 @@ static int tdo24m_probe(struct spi_devic spi_message_init(m); - x->cs_change = 1; + x->cs_change = 0; x->tx_buf = &lcd->buf[0]; spi_message_add_tail(x, m); --- 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_devic struct spi_message msg; struct spi_transfer xfer = { .len = 1, - .cs_change = 1, + .cs_change = 0, .tx_buf = buf, };