From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Epler Subject: [PATCH 4/4] spidev-s3c64xx: allocate dma channel at startup Date: Mon, 1 Sep 2014 09:30:35 -0500 Message-ID: <1409581835-70814-5-git-send-email-jepler@unpythonic.net> References: <1409581835-70814-1-git-send-email-jepler@unpythonic.net> To: linux-rt-users@vger.kernel.org Return-path: Received: from rrcs-76-79-27-186.west.biz.rr.com ([76.79.27.186]:48319 "EHLO rrcs-76-79-27-186.west.biz.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754516AbaIAPAd (ORCPT ); Mon, 1 Sep 2014 11:00:33 -0400 In-Reply-To: <1409581835-70814-1-git-send-email-jepler@unpythonic.net> Sender: linux-rt-users-owner@vger.kernel.org List-ID: it appears that acquire_dma introduces intolerable delays; the system is fine with the dma channnels allocated all the time. --- drivers/spi/spi-s3c64xx.c | 15 +++++++-------- 1 file changed, 7 insertions(+), 8 deletions(-) diff --git a/drivers/spi/spi-s3c64xx.c b/drivers/spi/spi-s3c64xx.c index 92de1b5..e6a46c9 100644 --- a/drivers/spi/spi-s3c64xx.c +++ b/drivers/spi/spi-s3c64xx.c @@ -797,10 +797,6 @@ static int s3c64xx_spi_prepare_transfer(struct spi_master *spi) { struct s3c64xx_spi_driver_data *sdd = spi_master_get_devdata(spi); - /* Acquire DMA channels */ - while (!acquire_dma(sdd)) - msleep(10); - pm_runtime_get_sync(&sdd->pdev->dev); return 0; @@ -810,10 +806,6 @@ static int s3c64xx_spi_unprepare_transfer(struct spi_master *spi) { struct s3c64xx_spi_driver_data *sdd = spi_master_get_devdata(spi); - /* Free DMA channels */ - sdd->ops->release(sdd->rx_dma.ch, &s3c64xx_spi_dma_client); - sdd->ops->release(sdd->tx_dma.ch, &s3c64xx_spi_dma_client); - pm_runtime_put(&sdd->pdev->dev); return 0; @@ -1344,6 +1336,9 @@ static int __init s3c64xx_spi_probe(struct platform_device *pdev) goto err7; } + // cannot fail(?) + acquire_dma(sdd); + writel(S3C64XX_SPI_INT_RX_OVERRUN_EN | S3C64XX_SPI_INT_RX_UNDERRUN_EN | S3C64XX_SPI_INT_TX_OVERRUN_EN | S3C64XX_SPI_INT_TX_UNDERRUN_EN, sdd->regs + S3C64XX_SPI_INT_EN); @@ -1396,6 +1391,10 @@ static int s3c64xx_spi_remove(struct platform_device *pdev) spi_unregister_master(master); + /* Free DMA channels */ + sdd->ops->release(sdd->rx_dma.ch, &s3c64xx_spi_dma_client); + sdd->ops->release(sdd->tx_dma.ch, &s3c64xx_spi_dma_client); + writel(0, sdd->regs + S3C64XX_SPI_INT_EN); free_irq(platform_get_irq(pdev, 0), sdd); -- 2.0.1