From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.9 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E2BE0C07E85 for ; Sun, 9 Dec 2018 22:14:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B1DDF20661 for ; Sun, 9 Dec 2018 22:14:04 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B1DDF20661 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=decadent.org.uk Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728484AbeLIWOD (ORCPT ); Sun, 9 Dec 2018 17:14:03 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:38000 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727862AbeLIWOB (ORCPT ); Sun, 9 Dec 2018 17:14:01 -0500 Received: from pub.yeoldevic.com ([81.174.156.145] helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1gW735-0002il-6e; Sun, 09 Dec 2018 21:55:39 +0000 Received: from ben by deadeye with local (Exim 4.91) (envelope-from ) id 1gW72g-0003VL-9B; Sun, 09 Dec 2018 21:55:14 +0000 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Laurent Pinchart" , "Geert Uytterhoeven" , "Mark Brown" Date: Sun, 09 Dec 2018 21:50:33 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) X-Patchwork-Hint: ignore Subject: [PATCH 3.16 203/328] spi: rspi: Handle dmaengine_prep_slave_sg() failures gracefully In-Reply-To: X-SA-Exim-Connect-IP: 81.174.156.145 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.62-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Geert Uytterhoeven commit 85912a88c1ebcad04a5cfec971771195ce8d6691 upstream. As typically a shmobile SoC has less DMA channels than devices that can use DMA, we may want to prioritize access to the DMA channels in the future. This means that dmaengine_prep_slave_sg() may start failing arbitrarily. Handle dmaengine_prep_slave_sg() failures gracefully by falling back to PIO. Signed-off-by: Geert Uytterhoeven Acked-by: Laurent Pinchart Signed-off-by: Mark Brown Signed-off-by: Ben Hutchings --- drivers/spi/spi-rspi.c | 30 ++++++++++++++++++++++-------- 1 file changed, 22 insertions(+), 8 deletions(-) --- a/drivers/spi/spi-rspi.c +++ b/drivers/spi/spi-rspi.c @@ -477,7 +477,7 @@ static int rspi_dma_transfer(struct rspi tx->sgl, tx->nents, DMA_TO_DEVICE, DMA_PREP_INTERRUPT | DMA_CTRL_ACK); if (!desc_tx) - return -EIO; + goto no_dma; irq_mask |= SPCR_SPTIE; } @@ -486,7 +486,7 @@ static int rspi_dma_transfer(struct rspi rx->sgl, rx->nents, DMA_FROM_DEVICE, DMA_PREP_INTERRUPT | DMA_CTRL_ACK); if (!desc_rx) - return -EIO; + goto no_dma; irq_mask |= SPCR_SPRIE; } @@ -540,6 +540,12 @@ static int rspi_dma_transfer(struct rspi enable_irq(rspi->rx_irq); return ret; + +no_dma: + pr_warn_once("%s %s: DMA not available, falling back to PIO\n", + dev_driver_string(&rspi->master->dev), + dev_name(&rspi->master->dev)); + return -EAGAIN; } static void rspi_receive_init(const struct rspi_data *rspi) @@ -593,8 +599,10 @@ static int rspi_common_transfer(struct r if (rspi->master->can_dma && __rspi_can_dma(rspi, xfer)) { /* rx_buf can be NULL on RSPI on SH in TX-only Mode */ - return rspi_dma_transfer(rspi, &xfer->tx_sg, - xfer->rx_buf ? &xfer->rx_sg : NULL); + ret = rspi_dma_transfer(rspi, &xfer->tx_sg, + xfer->rx_buf ? &xfer->rx_sg : NULL); + if (ret != -EAGAIN) + return ret; } ret = rspi_pio_transfer(rspi, xfer->tx_buf, xfer->rx_buf, xfer->len); @@ -648,8 +656,11 @@ static int qspi_transfer_out(struct rspi { int ret; - if (rspi->master->can_dma && __rspi_can_dma(rspi, xfer)) - return rspi_dma_transfer(rspi, &xfer->tx_sg, NULL); + if (rspi->master->can_dma && __rspi_can_dma(rspi, xfer)) { + ret = rspi_dma_transfer(rspi, &xfer->tx_sg, NULL); + if (ret != -EAGAIN) + return ret; + } ret = rspi_pio_transfer(rspi, xfer->tx_buf, NULL, xfer->len); if (ret < 0) @@ -663,8 +674,11 @@ static int qspi_transfer_out(struct rspi static int qspi_transfer_in(struct rspi_data *rspi, struct spi_transfer *xfer) { - if (rspi->master->can_dma && __rspi_can_dma(rspi, xfer)) - return rspi_dma_transfer(rspi, NULL, &xfer->rx_sg); + if (rspi->master->can_dma && __rspi_can_dma(rspi, xfer)) { + int ret = rspi_dma_transfer(rspi, NULL, &xfer->rx_sg); + if (ret != -EAGAIN) + return ret; + } return rspi_pio_transfer(rspi, NULL, xfer->rx_buf, xfer->len); }