From patchwork Sat Mar 30 09:31:00 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Martin Sperl X-Patchwork-Id: 10878203 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id EA19B1669 for ; Sat, 30 Mar 2019 09:31:22 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id D4A41290CC for ; Sat, 30 Mar 2019 09:31:22 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id C8C88290D6; Sat, 30 Mar 2019 09:31:22 +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=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, 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 578DA290CC for ; Sat, 30 Mar 2019 09:31:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730438AbfC3JbW (ORCPT ); Sat, 30 Mar 2019 05:31:22 -0400 Received: from 212-186-180-163.static.upcbusiness.at ([212.186.180.163]:55020 "EHLO cgate.sperl.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730372AbfC3JbV (ORCPT ); Sat, 30 Mar 2019 05:31:21 -0400 Received: from hc1.intern.sperl.org (account martin@sperl.org [10.10.10.59] verified) by sperl.org (CommuniGate Pro SMTP 6.2.1 _community_) with ESMTPSA id 7760020; Sat, 30 Mar 2019 09:31:12 +0000 From: kernel@martin.sperl.org To: Mark Brown , Eric Anholt , Stefan Wahren , Hubert Denkmair , linux-spi@vger.kernel.org, linux-rpi-kernel@lists.infradead.org, linux-arm-kernel@lists.infradead.org Cc: Martin Sperl Subject: [PATCH V3 3/9] spi: bcm2835aux: fix corruptions for longer spi transfers Date: Sat, 30 Mar 2019 09:31:00 +0000 Message-Id: <20190330093106.20723-4-kernel@martin.sperl.org> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20190330093106.20723-1-kernel@martin.sperl.org> References: <20190330093106.20723-1-kernel@martin.sperl.org> Sender: linux-spi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-spi@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Martin Sperl On long running tests with a mcp2517fd can controller it showed that on rare occations the data read shows corruptions for longer spi transfers. Example of a 22 byte transfer: expected (as captured on logic analyzer): FF FF 78 00 00 00 08 06 00 00 91 20 77 56 84 85 86 87 88 89 8a 8b read by the driver: FF FF 78 00 00 00 08 06 00 00 91 20 77 56 84 88 89 8a 00 00 8b 9b To fix this use BCM2835_AUX_SPI_STAT_RX_LVL to determine when we may read data from the fifo reliably without any corruption. Surprisingly the only values ever empirically read in BCM2835_AUX_SPI_STAT_RX_LVL are 0x00, 0x10, 0x20 and 0x30. So whenever the mask is not 0 we can read from the fifo in a safe manner. The patch has now been tested intensively and we are no longer able to reproduce the "RX" issue any longer. Fixes: 1ea29b39f4c812ec ("spi: bcm2835aux: add bcm2835 auxiliary spi device...") Reported-by: Hubert Denkmair Signed-off-by: Martin Sperl --- drivers/spi/spi-bcm2835aux.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) -- 2.11.0 diff --git a/drivers/spi/spi-bcm2835aux.c b/drivers/spi/spi-bcm2835aux.c index 0838dbda57c7..d9e62f717a45 100644 --- a/drivers/spi/spi-bcm2835aux.c +++ b/drivers/spi/spi-bcm2835aux.c @@ -180,12 +180,12 @@ static void bcm2835aux_spi_reset_hw(struct bcm2835aux_spi *bs) static void bcm2835aux_spi_transfer_helper(struct bcm2835aux_spi *bs) { + u32 stat = bcm2835aux_rd(bs, BCM2835_AUX_SPI_STAT); + /* check if we have data to read */ - while (bs->rx_len && - (!(bcm2835aux_rd(bs, BCM2835_AUX_SPI_STAT) & - BCM2835_AUX_SPI_STAT_RX_EMPTY))) { + for (; bs->rx_len && (stat & BCM2835_AUX_SPI_STAT_RX_LVL); + stat = bcm2835aux_rd(bs, BCM2835_AUX_SPI_STAT)) bcm2835aux_rd_fifo(bs); - } /* check if we have data to write */ while (bs->tx_len &&