From patchwork Wed Oct 10 17:09:36 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lubomir Rintel X-Patchwork-Id: 10634881 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 41EBE3CF1 for ; Wed, 10 Oct 2018 17:10:40 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 090E4299ED for ; Wed, 10 Oct 2018 17:10:40 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id F10402A6DE; Wed, 10 Oct 2018 17:10:39 +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 77406299ED for ; Wed, 10 Oct 2018 17:10:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727633AbeJKAdh (ORCPT ); Wed, 10 Oct 2018 20:33:37 -0400 Received: from shell.v3.sk ([90.176.6.54]:54280 "EHLO shell.v3.sk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726525AbeJKAdh (ORCPT ); Wed, 10 Oct 2018 20:33:37 -0400 Received: from localhost (localhost [127.0.0.1]) by zimbra.v3.sk (Postfix) with ESMTP id 59D09BCFB4; Wed, 10 Oct 2018 19:10:31 +0200 (CEST) Received: from shell.v3.sk ([127.0.0.1]) by localhost (zimbra.v3.sk [127.0.0.1]) (amavisd-new, port 10032) with ESMTP id Ru0PvWjLugRn; Wed, 10 Oct 2018 19:10:06 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by zimbra.v3.sk (Postfix) with ESMTP id 5E881B8064; Wed, 10 Oct 2018 19:09:59 +0200 (CEST) X-Virus-Scanned: amavisd-new at zimbra.v3.sk Received: from shell.v3.sk ([127.0.0.1]) by localhost (zimbra.v3.sk [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id FmnBgW3ay-B2; Wed, 10 Oct 2018 19:09:57 +0200 (CEST) Received: from belphegor.lan (ip-89-102-31-34.net.upcbroadband.cz [89.102.31.34]) by zimbra.v3.sk (Postfix) with ESMTPSA id A0214BCF91; Wed, 10 Oct 2018 19:09:55 +0200 (CEST) From: Lubomir Rintel To: Mark Brown , Geert Uytterhoeven Cc: James Cameron , Rob Herring , Mark Rutland , Eric Miao , Haojian Zhuang , Daniel Mack , Robert Jarzmik , linux-spi@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Lubomir Rintel Subject: [PATCH 11/11] spi: pxa2xx: Deal with the leftover garbage in TXFIFO Date: Wed, 10 Oct 2018 19:09:36 +0200 Message-Id: <20181010170936.316862-12-lkundrak@v3.sk> X-Mailer: git-send-email 2.19.0 In-Reply-To: <20181010170936.316862-1-lkundrak@v3.sk> References: <20181010170936.316862-1-lkundrak@v3.sk> 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 There doesn't seem to be a way to empty TXFIFO on MMP2. The datasheet is super-secret and the method described in Armada 16x manual won't work: "The TXFIFO and RXFIFO are cleared to 0b0 when the SSPx port is reset or disabled (by writing a 0b0 to the field in the SSP Control Register 0)." # devmem 0xd4037008 # read SSSR 0x0000F204 # devmem 0xd4037000 32 0x80 # SSE off in SSCR0 # devmem 0xd4037000 32 0x87 # SSE on # devmem 0xd4037008 0x0000F204 ^ TXFIFO level is still 2. Sigh. The OLPC 1.75 boot firmware leaves two bytes in the TXFIFO. Those are basically throwaway bytes used in response to the messages from the EC. The OLPC kernel copes with this by power-cycling the hardware. Perhaps the firmware should do this instead. Other than that, there's not much we can do other than complain loudly until the garbage gets drained and discard the actual data... For the OLPC EC this will work just fine and pushing more data to TXFIFO would break further transactions. Signed-off-by: Lubomir Rintel Acked-by: Pavel Machek --- drivers/spi/spi-pxa2xx.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/drivers/spi/spi-pxa2xx.c b/drivers/spi/spi-pxa2xx.c index a3b4b12c1077..2662b99d4439 100644 --- a/drivers/spi/spi-pxa2xx.c +++ b/drivers/spi/spi-pxa2xx.c @@ -1076,6 +1076,20 @@ static int pxa2xx_spi_transfer_one(struct spi_controller *master, pxa2xx_spi_write(drv_data, SSTO, chip->timeout); } + if (drv_data->ssp_type == MMP2_SSP) { + u8 tx_level = (pxa2xx_spi_read(drv_data, SSSR) + & SSSR_TFL_MASK) >> 8; + + if (tx_level) { + /* On MMP2, flipping SSE doesn't to empty TXFIFO. */ + dev_warn(&spi->dev, "%d bytes of garbage in TXFIFO!\n", + tx_level); + if (tx_level > transfer->len) + tx_level = transfer->len; + drv_data->tx += tx_level; + } + } + if (spi_controller_is_slave(master)) { while (drv_data->write(drv_data)) ;