From patchwork Tue Nov 13 10:22:28 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lubomir Rintel X-Patchwork-Id: 10680201 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 DA93B13B5 for ; Tue, 13 Nov 2018 10:23:23 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id CA36829BAF for ; Tue, 13 Nov 2018 10:23:23 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id BD6DA29BB3; Tue, 13 Nov 2018 10:23:23 +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 6286E29BAF for ; Tue, 13 Nov 2018 10:23:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732360AbeKMUUh (ORCPT ); Tue, 13 Nov 2018 15:20:37 -0500 Received: from shell.v3.sk ([90.176.6.54]:38301 "EHLO shell.v3.sk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732176AbeKMUUh (ORCPT ); Tue, 13 Nov 2018 15:20:37 -0500 Received: from localhost (localhost [127.0.0.1]) by zimbra.v3.sk (Postfix) with ESMTP id 9CD04C6B20; Tue, 13 Nov 2018 11:23:07 +0100 (CET) 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 e9yinJyvnevU; Tue, 13 Nov 2018 11:22:55 +0100 (CET) Received: from localhost (localhost [127.0.0.1]) by zimbra.v3.sk (Postfix) with ESMTP id 43AD9C6B1F; Tue, 13 Nov 2018 11:22:48 +0100 (CET) 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 10wfXwgnolqz; Tue, 13 Nov 2018 11:22:44 +0100 (CET) Received: from belphegor.brq.redhat.com (nat-pool-brq-t.redhat.com [213.175.37.10]) by zimbra.v3.sk (Postfix) with ESMTPSA id 5CACFC6B30; Tue, 13 Nov 2018 11:22:42 +0100 (CET) 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 v3 6/6] spi: pxa2xx: Deal with the leftover garbage in TXFIFO Date: Tue, 13 Nov 2018 11:22:28 +0100 Message-Id: <20181113102228.820214-7-lkundrak@v3.sk> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20181113102228.820214-1-lkundrak@v3.sk> References: <20181113102228.820214-1-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 0x07 # 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 --- Changes since v1: - Fixed a commit message typo (spotted by James Cameron) 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 7e5aab0af501..29e6025f104c 100644 --- a/drivers/spi/spi-pxa2xx.c +++ b/drivers/spi/spi-pxa2xx.c @@ -1078,6 +1078,20 @@ 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)) ;