From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S966247Ab3DRJkx (ORCPT ); Thu, 18 Apr 2013 05:40:53 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:39993 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756151Ab3DRJRT (ORCPT ); Thu, 18 Apr 2013 05:17:19 -0400 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Anatolij Gustschin , Mark Brown , Luis Henriques Subject: [PATCH 04/72] spi/mpc512x-psc: optionally keep PSC SS asserted across xfer segmensts Date: Thu, 18 Apr 2013 10:15:49 +0100 Message-Id: <1366276617-3553-5-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 1.8.1.2 In-Reply-To: <1366276617-3553-1-git-send-email-luis.henriques@canonical.com> References: <1366276617-3553-1-git-send-email-luis.henriques@canonical.com> X-Extended-Stable: 3.5 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.5.7.11 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Anatolij Gustschin commit 1ad849aee5f53353ed88d9cd3d68a51b03a7d44f upstream. Some SPI slave devices require asserted chip select signal across multiple transfer segments of an SPI message. Currently the driver always de-asserts the internal SS signal for every single transfer segment of the message and ignores the 'cs_change' flag of the transfer description. Disable the internal chip select (SS) only if this is needed and indicated by the 'cs_change' flag. Without this change, each partial transfer of a surrounding multi-part SPI transaction might erroneously change the SS signal, which might prevent slaves from answering the request that was sent in a previous transfer segment because the transaction could be considered aborted (SS was de-asserted before reading the response). Reported-by: Gerhard Sittig Signed-off-by: Anatolij Gustschin Signed-off-by: Mark Brown Signed-off-by: Luis Henriques --- drivers/spi/spi-mpc512x-psc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/spi/spi-mpc512x-psc.c b/drivers/spi/spi-mpc512x-psc.c index 4c63f77..2e2b04f 100644 --- a/drivers/spi/spi-mpc512x-psc.c +++ b/drivers/spi/spi-mpc512x-psc.c @@ -164,7 +164,7 @@ static int mpc512x_psc_spi_transfer_rxtx(struct spi_device *spi, for (i = count; i > 0; i--) { data = tx_buf ? *tx_buf++ : 0; - if (len == EOFBYTE) + if (len == EOFBYTE && t->cs_change) setbits32(&fifo->txcmd, MPC512x_PSC_FIFO_EOF); out_8(&fifo->txdata_8, data); len--; -- 1.8.1.2