From patchwork Fri May 29 13:11:56 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Serge Semin X-Patchwork-Id: 11578613 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 9B4BF912 for ; Fri, 29 May 2020 13:13:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8DB08207BC for ; Fri, 29 May 2020 13:13:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727018AbgE2NMW (ORCPT ); Fri, 29 May 2020 09:12:22 -0400 Received: from mail.baikalelectronics.com ([87.245.175.226]:48200 "EHLO mail.baikalelectronics.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726701AbgE2NMU (ORCPT ); Fri, 29 May 2020 09:12:20 -0400 Received: from localhost (unknown [127.0.0.1]) by mail.baikalelectronics.ru (Postfix) with ESMTP id D72008029EA0; Fri, 29 May 2020 13:12:17 +0000 (UTC) X-Virus-Scanned: amavisd-new at baikalelectronics.ru Received: from mail.baikalelectronics.ru ([127.0.0.1]) by localhost (mail.baikalelectronics.ru [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id wrc_ijKojq8N; Fri, 29 May 2020 16:12:17 +0300 (MSK) From: Serge Semin To: Mark Brown CC: Serge Semin , Serge Semin , Andy Shevchenko , Alexey Malahov , Thomas Bogendoerfer , Arnd Bergmann , Feng Tang , Rob Herring , , , , Subject: [PATCH v6 07/16] spi: dw: Use DMA max burst to set the request thresholds Date: Fri, 29 May 2020 16:11:56 +0300 Message-ID: <20200529131205.31838-8-Sergey.Semin@baikalelectronics.ru> In-Reply-To: <20200529131205.31838-1-Sergey.Semin@baikalelectronics.ru> References: <20200529131205.31838-1-Sergey.Semin@baikalelectronics.ru> MIME-Version: 1.0 X-ClientProxiedBy: MAIL.baikal.int (192.168.51.25) To mail (192.168.51.25) Sender: linux-spi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-spi@vger.kernel.org Each channel of DMA controller may have a limited length of burst transaction (number of IO operations performed at ones in a single DMA client request). This parameter can be used to setup the most optimal DMA Tx/Rx data level values. In order to avoid the Tx buffer overrun we can set the DMA Tx level to be of FIFO depth minus the maximum burst transactions length. To prevent the Rx buffer underflow the DMA Rx level should be set to the maximum burst transactions length. This commit setups the DMA channels and the DW SPI DMA Tx/Rx levels in accordance with these rules. Signed-off-by: Serge Semin Reviewed-by: Andy Shevchenko Cc: Alexey Malahov Cc: Thomas Bogendoerfer Cc: Arnd Bergmann Cc: Feng Tang Cc: Rob Herring Cc: linux-mips@vger.kernel.org Cc: devicetree@vger.kernel.org --- Changelog v3: - Use min() method to calculate the optimal burst values. --- drivers/spi/spi-dw-mid.c | 37 +++++++++++++++++++++++++++++++++---- drivers/spi/spi-dw.h | 2 ++ 2 files changed, 35 insertions(+), 4 deletions(-) diff --git a/drivers/spi/spi-dw-mid.c b/drivers/spi/spi-dw-mid.c index 189b517f77fc..1cf9e3ffe07b 100644 --- a/drivers/spi/spi-dw-mid.c +++ b/drivers/spi/spi-dw-mid.c @@ -36,6 +36,31 @@ static bool mid_spi_dma_chan_filter(struct dma_chan *chan, void *param) return true; } +static void mid_spi_maxburst_init(struct dw_spi *dws) +{ + struct dma_slave_caps caps; + u32 max_burst, def_burst; + int ret; + + def_burst = dws->fifo_len / 2; + + ret = dma_get_slave_caps(dws->rxchan, &caps); + if (!ret && caps.max_burst) + max_burst = caps.max_burst; + else + max_burst = RX_BURST_LEVEL; + + dws->rxburst = min(max_burst, def_burst); + + ret = dma_get_slave_caps(dws->txchan, &caps); + if (!ret && caps.max_burst) + max_burst = caps.max_burst; + else + max_burst = TX_BURST_LEVEL; + + dws->txburst = min(max_burst, def_burst); +} + static int mid_spi_dma_init_mfld(struct device *dev, struct dw_spi *dws) { struct dw_dma_slave slave = { @@ -73,6 +98,8 @@ static int mid_spi_dma_init_mfld(struct device *dev, struct dw_spi *dws) init_completion(&dws->dma_completion); + mid_spi_maxburst_init(dws); + return 0; free_rxchan: @@ -100,6 +127,8 @@ static int mid_spi_dma_init_generic(struct device *dev, struct dw_spi *dws) init_completion(&dws->dma_completion); + mid_spi_maxburst_init(dws); + return 0; } @@ -229,7 +258,7 @@ static struct dma_async_tx_descriptor *dw_spi_dma_prepare_tx(struct dw_spi *dws, memset(&txconf, 0, sizeof(txconf)); txconf.direction = DMA_MEM_TO_DEV; txconf.dst_addr = dws->dma_addr; - txconf.dst_maxburst = TX_BURST_LEVEL; + txconf.dst_maxburst = dws->txburst; txconf.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES; txconf.dst_addr_width = convert_dma_width(dws->n_bytes); txconf.device_fc = false; @@ -321,7 +350,7 @@ static struct dma_async_tx_descriptor *dw_spi_dma_prepare_rx(struct dw_spi *dws, memset(&rxconf, 0, sizeof(rxconf)); rxconf.direction = DMA_DEV_TO_MEM; rxconf.src_addr = dws->dma_addr; - rxconf.src_maxburst = RX_BURST_LEVEL; + rxconf.src_maxburst = dws->rxburst; rxconf.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES; rxconf.src_addr_width = convert_dma_width(dws->n_bytes); rxconf.device_fc = false; @@ -346,8 +375,8 @@ static int mid_spi_dma_setup(struct dw_spi *dws, struct spi_transfer *xfer) { u16 imr = 0, dma_ctrl = 0; - dw_writel(dws, DW_SPI_DMARDLR, RX_BURST_LEVEL - 1); - dw_writel(dws, DW_SPI_DMATDLR, TX_BURST_LEVEL); + dw_writel(dws, DW_SPI_DMARDLR, dws->rxburst - 1); + dw_writel(dws, DW_SPI_DMATDLR, dws->fifo_len - dws->txburst); if (xfer->tx_buf) { dma_ctrl |= SPI_DMA_TDMAE; diff --git a/drivers/spi/spi-dw.h b/drivers/spi/spi-dw.h index 9585d0c83a6d..9247670fcdfb 100644 --- a/drivers/spi/spi-dw.h +++ b/drivers/spi/spi-dw.h @@ -142,7 +142,9 @@ struct dw_spi { /* DMA info */ struct dma_chan *txchan; + u32 txburst; struct dma_chan *rxchan; + u32 rxburst; unsigned long dma_chan_busy; dma_addr_t dma_addr; /* phy address of the Data register */ const struct dw_spi_dma_ops *dma_ops;