Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S939035AbdLSKZt (ORCPT ); Tue, 19 Dec 2017 05:25:49 -0500 Received: from esa2.microchip.iphmx.com ([68.232.149.84]:16397 "EHLO esa2.microchip.iphmx.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760081AbdLSKZr (ORCPT ); Tue, 19 Dec 2017 05:25:47 -0500 X-IronPort-AV: E=Sophos;i="5.45,426,1508828400"; d="scan'208";a="9735265" Subject: Re: [PATCH v2] spi: atmel: Implements transfers with bounce buffer To: Radu Pirea , CC: , , , , References: <1513093032-11570-1-git-send-email-radu.pirea@microchip.com> From: Nicolas Ferre Organization: microchip Message-ID: Date: Tue, 19 Dec 2017 11:25:48 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.5.0 MIME-Version: 1.0 In-Reply-To: <1513093032-11570-1-git-send-email-radu.pirea@microchip.com> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6968 Lines: 204 On 12/12/2017 at 16:37, Radu Pirea wrote: > This patch enables DMA transfers for Atmel SAM9 SoCs and implements a bounce > buffer for transfers which have vmalloc allocated buffers. Those buffers are > not cache coherent even if they have been transformed into sg lists. UBIFS > is affected by this cache coherency issue. > > In this patch I also reverted "spi: atmel: fix corrupted data issue on SAM9 > family SoCs"(7094576ccdc3acfe1e06a1e2ab547add375baf7f). > > > Signed-off-by: Radu Pirea Acked-by: Nicolas Ferre Best regards, Nicolas > --- > Please ignore the previous version. I messed up with file names. > drivers/spi/spi-atmel.c | 113 +++++++++++++++++++++++++++++++++++------------- > 1 file changed, 84 insertions(+), 29 deletions(-) > > diff --git a/drivers/spi/spi-atmel.c b/drivers/spi/spi-atmel.c > index f95da36..198b4cd 100644 > --- a/drivers/spi/spi-atmel.c > +++ b/drivers/spi/spi-atmel.c > @@ -291,6 +291,10 @@ struct atmel_spi { > struct spi_transfer *current_transfer; > int current_remaining_bytes; > int done_status; > + dma_addr_t dma_addr_rx_bbuf; > + dma_addr_t dma_addr_tx_bbuf; > + void *addr_rx_bbuf; > + void *addr_tx_bbuf; > > struct completion xfer_completion; > > @@ -436,6 +440,11 @@ static void atmel_spi_unlock(struct atmel_spi *as) __releases(&as->lock) > spin_unlock_irqrestore(&as->lock, as->flags); > } > > +static inline bool atmel_spi_is_vmalloc_xfer(struct spi_transfer *xfer) > +{ > + return is_vmalloc_addr(xfer->tx_buf) || is_vmalloc_addr(xfer->rx_buf); > +} > + > static inline bool atmel_spi_use_dma(struct atmel_spi *as, > struct spi_transfer *xfer) > { > @@ -448,7 +457,12 @@ static bool atmel_spi_can_dma(struct spi_master *master, > { > struct atmel_spi *as = spi_master_get_devdata(master); > > - return atmel_spi_use_dma(as, xfer); > + if (IS_ENABLED(CONFIG_SOC_SAM_V4_V5)) > + return atmel_spi_use_dma(as, xfer) && > + !atmel_spi_is_vmalloc_xfer(xfer); > + else > + return atmel_spi_use_dma(as, xfer); > + > } > > static int atmel_spi_dma_slave_config(struct atmel_spi *as, > @@ -594,6 +608,11 @@ static void dma_callback(void *data) > struct spi_master *master = data; > struct atmel_spi *as = spi_master_get_devdata(master); > > + if (is_vmalloc_addr(as->current_transfer->rx_buf) && > + IS_ENABLED(CONFIG_SOC_SAM_V4_V5)) { > + memcpy(as->current_transfer->rx_buf, as->addr_rx_bbuf, > + as->current_transfer->len); > + } > complete(&as->xfer_completion); > } > > @@ -744,17 +763,41 @@ static int atmel_spi_next_xfer_dma_submit(struct spi_master *master, > goto err_exit; > > /* Send both scatterlists */ > - rxdesc = dmaengine_prep_slave_sg(rxchan, > - xfer->rx_sg.sgl, xfer->rx_sg.nents, > - DMA_FROM_DEVICE, > - DMA_PREP_INTERRUPT | DMA_CTRL_ACK); > + if (atmel_spi_is_vmalloc_xfer(xfer) && > + IS_ENABLED(CONFIG_SOC_SAM_V4_V5)) { > + rxdesc = dmaengine_prep_slave_single(rxchan, > + as->dma_addr_rx_bbuf, > + xfer->len, > + DMA_FROM_DEVICE, > + DMA_PREP_INTERRUPT | > + DMA_CTRL_ACK); > + } else { > + rxdesc = dmaengine_prep_slave_sg(rxchan, > + xfer->rx_sg.sgl, > + xfer->rx_sg.nents, > + DMA_FROM_DEVICE, > + DMA_PREP_INTERRUPT | > + DMA_CTRL_ACK); > + } > if (!rxdesc) > goto err_dma; > > - txdesc = dmaengine_prep_slave_sg(txchan, > - xfer->tx_sg.sgl, xfer->tx_sg.nents, > - DMA_TO_DEVICE, > - DMA_PREP_INTERRUPT | DMA_CTRL_ACK); > + if (atmel_spi_is_vmalloc_xfer(xfer) && > + IS_ENABLED(CONFIG_SOC_SAM_V4_V5)) { > + memcpy(as->addr_tx_bbuf, xfer->tx_buf, xfer->len); > + txdesc = dmaengine_prep_slave_single(txchan, > + as->dma_addr_tx_bbuf, > + xfer->len, DMA_TO_DEVICE, > + DMA_PREP_INTERRUPT | > + DMA_CTRL_ACK); > + } else { > + txdesc = dmaengine_prep_slave_sg(txchan, > + xfer->tx_sg.sgl, > + xfer->tx_sg.nents, > + DMA_TO_DEVICE, > + DMA_PREP_INTERRUPT | > + DMA_CTRL_ACK); > + } > if (!txdesc) > goto err_dma; > > @@ -1426,27 +1469,7 @@ static void atmel_get_caps(struct atmel_spi *as) > > as->caps.is_spi2 = version > 0x121; > as->caps.has_wdrbt = version >= 0x210; > -#ifdef CONFIG_SOC_SAM_V4_V5 > - /* > - * Atmel SoCs based on ARM9 (SAM9x) cores should not use spi_map_buf() > - * since this later function tries to map buffers with dma_map_sg() > - * even if they have not been allocated inside DMA-safe areas. > - * On SoCs based on Cortex A5 (SAMA5Dx), it works anyway because for > - * those ARM cores, the data cache follows the PIPT model. > - * Also the L2 cache controller of SAMA5D2 uses the PIPT model too. > - * In case of PIPT caches, there cannot be cache aliases. > - * However on ARM9 cores, the data cache follows the VIVT model, hence > - * the cache aliases issue can occur when buffers are allocated from > - * DMA-unsafe areas, by vmalloc() for instance, where cache coherency is > - * not taken into account or at least not handled completely (cache > - * lines of aliases are not invalidated). > - * This is not a theorical issue: it was reproduced when trying to mount > - * a UBI file-system on a at91sam9g35ek board. > - */ > - as->caps.has_dma_support = false; > -#else > as->caps.has_dma_support = version >= 0x212; > -#endif > as->caps.has_pdc_support = version < 0x212; > } > > @@ -1592,6 +1615,30 @@ static int atmel_spi_probe(struct platform_device *pdev) > as->use_pdc = true; > } > > + if (IS_ENABLED(CONFIG_SOC_SAM_V4_V5)) { > + as->addr_rx_bbuf = dma_alloc_coherent(&pdev->dev, > + SPI_MAX_DMA_XFER, > + &as->dma_addr_rx_bbuf, > + GFP_KERNEL | GFP_DMA); > + if (!as->addr_rx_bbuf) { > + as->use_dma = false; > + } else { > + as->addr_tx_bbuf = dma_alloc_coherent(&pdev->dev, > + SPI_MAX_DMA_XFER, > + &as->dma_addr_tx_bbuf, > + GFP_KERNEL | GFP_DMA); > + if (!as->addr_tx_bbuf) { > + as->use_dma = false; > + dma_free_coherent(&pdev->dev, SPI_MAX_DMA_XFER, > + as->addr_rx_bbuf, > + as->dma_addr_rx_bbuf); > + } > + } > + if(!as->use_dma) > + dev_info(master->dev.parent, > + " can not allocate dma coherent memory\n"); > + } > + > if (as->caps.has_dma_support && !as->use_dma) > dev_info(&pdev->dev, "Atmel SPI Controller using PIO only\n"); > > @@ -1665,6 +1712,14 @@ static int atmel_spi_remove(struct platform_device *pdev) > if (as->use_dma) { > atmel_spi_stop_dma(master); > atmel_spi_release_dma(master); > + if (IS_ENABLED(CONFIG_SOC_SAM_V4_V5)) { > + dma_free_coherent(&pdev->dev, SPI_MAX_DMA_XFER, > + as->addr_tx_bbuf, > + as->dma_addr_tx_bbuf); > + dma_free_coherent(&pdev->dev, SPI_MAX_DMA_XFER, > + as->addr_rx_bbuf, > + as->dma_addr_rx_bbuf); > + } > } > > spi_writel(as, CR, SPI_BIT(SWRST)); > -- Nicolas Ferre