linux-kernel - Re: [PATCH v4 06/16] spi: dw: Parameterize the DMA Rx/Tx burst length

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Date:   Fri, 22 May 2020 14:06:19 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Serge Semin <Sergey.Semin@...kalelectronics.ru>
Cc:     Mark Brown <broonie@...nel.org>,
        Serge Semin <fancer.lancer@...il.com>,
        Georgy Vlasov <Georgy.Vlasov@...kalelectronics.ru>,
        Ramil Zaripov <Ramil.Zaripov@...kalelectronics.ru>,
        Alexey Malahov <Alexey.Malahov@...kalelectronics.ru>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        Paul Burton <paulburton@...nel.org>,
        Ralf Baechle <ralf@...ux-mips.org>,
        Arnd Bergmann <arnd@...db.de>,
        Rob Herring <robh+dt@...nel.org>, linux-mips@...r.kernel.org,
        devicetree@...r.kernel.org,
        Wan Ahmad Zainie <wan.ahmad.zainie.wan.mohamad@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Jarkko Nikula <jarkko.nikula@...ux.intel.com>,
        linux-spi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 06/16] spi: dw: Parameterize the DMA Rx/Tx burst length

On Fri, May 22, 2020 at 03:07:55AM +0300, Serge Semin wrote:
> It isn't good to have numeric literals in the code especially if there
> are multiple of them and they are related. Let's replace the Tx and Rx
> burst level literals with the corresponding constants.


You missed my tag.

> Co-developed-by: Georgy Vlasov <Georgy.Vlasov@...kalelectronics.ru>
> Signed-off-by: Georgy Vlasov <Georgy.Vlasov@...kalelectronics.ru>
> Co-developed-by: Ramil Zaripov <Ramil.Zaripov@...kalelectronics.ru>
> Signed-off-by: Ramil Zaripov <Ramil.Zaripov@...kalelectronics.ru>
> Signed-off-by: Serge Semin <Sergey.Semin@...kalelectronics.ru>
> Cc: Alexey Malahov <Alexey.Malahov@...kalelectronics.ru>
> Cc: Thomas Bogendoerfer <tsbogend@...ha.franken.de>
> Cc: Paul Burton <paulburton@...nel.org>
> Cc: Ralf Baechle <ralf@...ux-mips.org>
> Cc: Arnd Bergmann <arnd@...db.de>
> Cc: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> Cc: Rob Herring <robh+dt@...nel.org>
> Cc: linux-mips@...r.kernel.org
> Cc: devicetree@...r.kernel.org
> 
> ---
> 
> Changelog v3:
> - Discard the dws->fifo_len utilization in the Tx FIFO DMA threshold
>   setting.
> ---
>  drivers/spi/spi-dw-mid.c | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/spi/spi-dw-mid.c b/drivers/spi/spi-dw-mid.c
> index c39bc8758339..1598c36c905f 100644
> --- a/drivers/spi/spi-dw-mid.c
> +++ b/drivers/spi/spi-dw-mid.c
> @@ -20,7 +20,9 @@
>  
>  #define WAIT_RETRIES	5
>  #define RX_BUSY		0
> +#define RX_BURST_LEVEL	16
>  #define TX_BUSY		1
> +#define TX_BURST_LEVEL	16
>  
>  static bool mid_spi_dma_chan_filter(struct dma_chan *chan, void *param)
>  {
> @@ -198,7 +200,7 @@ 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 = 16;
> +	txconf.dst_maxburst = TX_BURST_LEVEL;
>  	txconf.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
>  	txconf.dst_addr_width = convert_dma_width(dws->n_bytes);
>  	txconf.device_fc = false;
> @@ -273,7 +275,7 @@ 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 = 16;
> +	rxconf.src_maxburst = RX_BURST_LEVEL;
>  	rxconf.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
>  	rxconf.src_addr_width = convert_dma_width(dws->n_bytes);
>  	rxconf.device_fc = false;
> @@ -298,8 +300,8 @@ 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, 0xf);
> -	dw_writel(dws, DW_SPI_DMATDLR, 0x10);
> +	dw_writel(dws, DW_SPI_DMARDLR, RX_BURST_LEVEL - 1);
> +	dw_writel(dws, DW_SPI_DMATDLR, TX_BURST_LEVEL);
>  
>  	if (xfer->tx_buf) {
>  		dma_ctrl |= SPI_DMA_TDMAE;
> -- 
> 2.25.1
> 

-- 
With Best Regards,
Andy Shevchenko