From patchwork Tue Feb 27 10:25:07 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eugen Hristev X-Patchwork-Id: 10244745 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 4089860211 for ; Tue, 27 Feb 2018 10:27:50 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 302A028844 for ; Tue, 27 Feb 2018 10:27:50 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 246B828876; Tue, 27 Feb 2018 10:27:50 +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=-6.9 required=2.0 tests=BAYES_00,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 875B928844 for ; Tue, 27 Feb 2018 10:27:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752695AbeB0K1t (ORCPT ); Tue, 27 Feb 2018 05:27:49 -0500 Received: from esa6.microchip.iphmx.com ([216.71.154.253]:51940 "EHLO esa6.microchip.iphmx.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752689AbeB0K1s (ORCPT ); Tue, 27 Feb 2018 05:27:48 -0500 X-IronPort-AV: E=Sophos;i="5.47,400,1515481200"; d="scan'208";a="9188935" Received: from smtpout.microchip.com (HELO email.microchip.com) ([198.175.253.82]) by esa6.microchip.iphmx.com with ESMTP/TLS/DHE-RSA-AES256-SHA; 27 Feb 2018 03:27:47 -0700 Received: from eh-station.microchip.com (10.10.76.4) by chn-sv-exch04.mchp-main.com (10.10.76.105) with Microsoft SMTP Server id 14.3.352.0; Tue, 27 Feb 2018 03:27:46 -0700 From: Eugen Hristev To: , , , , CC: Eugen Hristev Subject: [PATCH] spi: atmel: init FIFOs before spi enable Date: Tue, 27 Feb 2018 12:25:07 +0200 Message-ID: <1519727107-5821-1-git-send-email-eugen.hristev@microchip.com> X-Mailer: git-send-email 2.7.4 MIME-Version: 1.0 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 The datasheet recommends initializing FIFOs before SPI enable. If we do not do it like this, there may be a strange behavior. We noticed that DMA does not work properly with FIFOs if we do not clear them beforehand or enable them before SPIEN. Signed-off-by: Eugen Hristev Acked-by: Nicolas Ferre --- drivers/spi/spi-atmel.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/drivers/spi/spi-atmel.c b/drivers/spi/spi-atmel.c index 6694709..0478758 100644 --- a/drivers/spi/spi-atmel.c +++ b/drivers/spi/spi-atmel.c @@ -1489,6 +1489,11 @@ static void atmel_spi_init(struct atmel_spi *as) { spi_writel(as, CR, SPI_BIT(SWRST)); spi_writel(as, CR, SPI_BIT(SWRST)); /* AT91SAM9263 Rev B workaround */ + + /* It is recommended to enable FIFOs first thing after reset */ + if (as->fifo_size) + spi_writel(as, CR, SPI_BIT(FIFOEN)); + if (as->caps.has_wdrbt) { spi_writel(as, MR, SPI_BIT(WDRBT) | SPI_BIT(MODFDIS) | SPI_BIT(MSTR)); @@ -1499,9 +1504,6 @@ static void atmel_spi_init(struct atmel_spi *as) if (as->use_pdc) spi_writel(as, PTCR, SPI_BIT(RXTDIS) | SPI_BIT(TXTDIS)); spi_writel(as, CR, SPI_BIT(SPIEN)); - - if (as->fifo_size) - spi_writel(as, CR, SPI_BIT(FIFOEN)); } static int atmel_spi_probe(struct platform_device *pdev)