From patchwork Fri May 22 00:07:56 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Serge Semin X-Patchwork-Id: 11564227 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 9278560D for ; Fri, 22 May 2020 00:08:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 84070206BE for ; Fri, 22 May 2020 00:08:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730585AbgEVAIp (ORCPT ); Thu, 21 May 2020 20:08:45 -0400 Received: from mail.baikalelectronics.com ([87.245.175.226]:41334 "EHLO mail.baikalelectronics.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730533AbgEVAIp (ORCPT ); Thu, 21 May 2020 20:08:45 -0400 Received: from localhost (unknown [127.0.0.1]) by mail.baikalelectronics.ru (Postfix) with ESMTP id 4084280005E8; Fri, 22 May 2020 00:08:41 +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 Po0_OGsCYQ-u; Fri, 22 May 2020 03:08:40 +0300 (MSK) From: Serge Semin To: Mark Brown CC: Serge Semin , Serge Semin , Andy Shevchenko , Alexey Malahov , Thomas Bogendoerfer , Paul Burton , Ralf Baechle , Arnd Bergmann , Rob Herring , , , Georgy Vlasov , Ramil Zaripov , Wan Ahmad Zainie , Thomas Gleixner , Jarkko Nikula , Clement Leger , Linus Walleij , , Subject: [PATCH v4 07/16] spi: dw: Use DMA max burst to set the request thresholds Date: Fri, 22 May 2020 03:07:56 +0300 Message-ID: <20200522000806.7381-8-Sergey.Semin@baikalelectronics.ru> In-Reply-To: <20200522000806.7381-1-Sergey.Semin@baikalelectronics.ru> References: <20200522000806.7381-1-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: Paul Burton Cc: Ralf Baechle Cc: Arnd Bergmann Cc: Andy Shevchenko 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 1598c36c905f..ac96b99ef226 100644 --- a/drivers/spi/spi-dw-mid.c +++ b/drivers/spi/spi-dw-mid.c @@ -35,6 +35,31 @@ 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 = { @@ -70,6 +95,8 @@ static int mid_spi_dma_init_mfld(struct device *dev, struct dw_spi *dws) dws->master->dma_rx = dws->rxchan; dws->master->dma_tx = dws->txchan; + mid_spi_maxburst_init(dws); + return 0; free_rxchan: @@ -95,6 +122,8 @@ static int mid_spi_dma_init_generic(struct device *dev, struct dw_spi *dws) dws->master->dma_rx = dws->rxchan; dws->master->dma_tx = dws->txchan; + mid_spi_maxburst_init(dws); + return 0; } @@ -200,7 +229,7 @@ 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; @@ -275,7 +304,7 @@ 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; @@ -300,8 +329,8 @@ 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 4902f937c3d7..d0c8b7d3a5d2 100644 --- a/drivers/spi/spi-dw.h +++ b/drivers/spi/spi-dw.h @@ -141,7 +141,9 @@ 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;