From patchwork Mon Oct 12 07:52:02 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vignesh Raghavendra X-Patchwork-Id: 7373151 Return-Path: X-Original-To: patchwork-linux-spi@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 62C79BF90C for ; Mon, 12 Oct 2015 08:07:49 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 9031B206D2 for ; Mon, 12 Oct 2015 08:07:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8E720206D9 for ; Mon, 12 Oct 2015 08:07:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751406AbbJLIHU (ORCPT ); Mon, 12 Oct 2015 04:07:20 -0400 Received: from devils.ext.ti.com ([198.47.26.153]:37637 "EHLO devils.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750890AbbJLIHR (ORCPT ); Mon, 12 Oct 2015 04:07:17 -0400 Received: from dflxv15.itg.ti.com ([128.247.5.124]) by devils.ext.ti.com (8.13.7/8.13.7) with ESMTP id t9C87Ebe028363; Mon, 12 Oct 2015 03:07:14 -0500 Received: from DFLE73.ent.ti.com (dfle73.ent.ti.com [128.247.5.110]) by dflxv15.itg.ti.com (8.14.3/8.13.8) with ESMTP id t9C87E60030755; Mon, 12 Oct 2015 03:07:14 -0500 Received: from dlep33.itg.ti.com (157.170.170.75) by DFLE73.ent.ti.com (128.247.5.110) with Microsoft SMTP Server id 14.3.224.2; Mon, 12 Oct 2015 03:07:14 -0500 Received: from uda0132425.apr.dhcp.ti.com (ileax41-snat.itg.ti.com [10.172.224.153]) by dlep33.itg.ti.com (8.14.3/8.13.8) with ESMTP id t9C87Cn0006756; Mon, 12 Oct 2015 03:07:12 -0500 From: Vignesh R To: Mark Brown CC: , , , Vignesh R Subject: [PATCH] spi: ti-qspi: Fix data corruption seen on r/w stress test Date: Mon, 12 Oct 2015 13:22:02 +0530 Message-ID: <1444636322-6772-1-git-send-email-vigneshr@ti.com> X-Mailer: git-send-email 2.6.1 MIME-Version: 1.0 Sender: linux-spi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-spi@vger.kernel.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, T_RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Writing invalid command to QSPI_SPI_CMD_REG will terminate current transfer and de-assert the chip select. This has to be done before calling spi_finalize_current_message(). Because spi_finalize_current_message() will mark the end of current message transfer and schedule the next transfer. If the chipselect is not de-asserted before calling spi_finalize_current_message() then the next transfer will overlap with the previous transfer leading to data corruption. __spi_pump_message() can be called either from kthread worker context or directly from the calling process's context. It is possible that these two calls can race against each other. But race is serialized by checking whether master->cur_msg == NULL (pointer to msg being handled by transfer_one() at present). The master->cur_msg is set to NULL when spi_finalize_current_message() is called on that message, which means calling spi_finalize_current_message() allows __spi_sync() to pump next message in calling process context. Now if spi-ti-qspi calls spi_finalize_current_message() before we terminate transfer at hardware side, if __spi_pump_message() is called from process context then the successive transactions can overlap. Fix this by moving writing invalid command to QSPI_SPI_CMD_REG to before calling spi_finalize_current_message() call. Cc: stable@vger.kernel.org # v3.12+ Signed-off-by: Vignesh R --- drivers/spi/spi-ti-qspi.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/drivers/spi/spi-ti-qspi.c b/drivers/spi/spi-ti-qspi.c index aa6d284131e0..81b84858cfee 100644 --- a/drivers/spi/spi-ti-qspi.c +++ b/drivers/spi/spi-ti-qspi.c @@ -410,11 +410,10 @@ static int ti_qspi_start_transfer_one(struct spi_master *master, mutex_unlock(&qspi->list_lock); + ti_qspi_write(qspi, qspi->cmd | QSPI_INVAL, QSPI_SPI_CMD_REG); m->status = status; spi_finalize_current_message(master); - ti_qspi_write(qspi, qspi->cmd | QSPI_INVAL, QSPI_SPI_CMD_REG); - return status; }