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Subject: Re: [PATCH v3 2/3] mtd: spi-nor: cadence-quadspi: Disable the DAC for
 Intel LGM SoC
To:     "Ramuthevar,Vadivel MuruganX" 
        <vadivel.muruganx.ramuthevar@linux.intel.com>,
        <linux-mtd@lists.infradead.org>
CC:     <linux-kernel@vger.kernel.org>, <devicetree@vger.kernel.org>,
        <dwmw2@infradead.org>, <computersforpeace@gmail.com>,
        <richard@nod.at>, <jwboyer@gmail.com>,
        <boris.brezillon@free-electrons.com>, <cyrille.pitchen@atmel.com>,
        <david.oberhollenzer@sigma-star.at>, <miquel.raynal@bootlin.com>,
        <tudor.ambarus@gmail.com>, <andriy.shevchenko@intel.com>,
        <cheol.yong.kim@intel.com>, <qi-ming.wu@intel.com>
References: <20190909104733.14273-1-vadivel.muruganx.ramuthevar@linux.intel.com>
 <20190909104733.14273-3-vadivel.muruganx.ramuthevar@linux.intel.com>
From:   Vignesh Raghavendra <vigneshr@ti.com>
Message-ID: <85355c80-1344-db22-ae31-0f20f30b9754@ti.com>
Date:   Wed, 16 Oct 2019 14:02:50 +0530
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On 09/09/19 4:17 PM, Ramuthevar,Vadivel MuruganX wrote:
> From: Ramuthevar Vadivel Murugan <vadivel.muruganx.ramuthevar@linux.intel.com>
> 
> on Intel's Lightning Mountain(LGM) SoCs QSPI controller do not use

s/on/On

> Direct Access Controller(DAC).
> 
> This patch introduces to properly disable the Direct Access Controller

"This patch adds a quirk to disable..." or something something similar

> for data transfer instead it uses indirect data transfer.
> 
> Signed-off-by: Ramuthevar Vadivel Murugan <vadivel.muruganx.ramuthevar@linux.intel.com>
> ---
>  drivers/mtd/spi-nor/Kconfig           |  2 +-
>  drivers/mtd/spi-nor/cadence-quadspi.c | 21 +++++++++++++++++++++
>  2 files changed, 22 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/mtd/spi-nor/Kconfig b/drivers/mtd/spi-nor/Kconfig
> index 6de83277ce8b..ba2e372ae514 100644
> --- a/drivers/mtd/spi-nor/Kconfig
> +++ b/drivers/mtd/spi-nor/Kconfig
> @@ -34,7 +34,7 @@ config SPI_ASPEED_SMC
>  
>  config SPI_CADENCE_QUADSPI
>  	tristate "Cadence Quad SPI controller"
> -	depends on OF && (ARM || ARM64 || COMPILE_TEST)
> +	depends on OF && (ARM || ARM64 || COMPILE_TEST || X86)
>  	help
>  	  Enable support for the Cadence Quad SPI Flash controller.
>  
> diff --git a/drivers/mtd/spi-nor/cadence-quadspi.c b/drivers/mtd/spi-nor/cadence-quadspi.c
> index 67f15a1f16fd..73b9fbd1508a 100644
> --- a/drivers/mtd/spi-nor/cadence-quadspi.c
> +++ b/drivers/mtd/spi-nor/cadence-quadspi.c
> @@ -33,6 +33,7 @@
>  
>  /* Quirks */
>  #define CQSPI_NEEDS_WR_DELAY		BIT(0)
> +#define CQSPI_DISABLE_DAC_MODE		BIT(1)
>  
>  /* Capabilities mask */
>  #define CQSPI_BASE_HWCAPS_MASK					\
> @@ -609,6 +610,13 @@ static int cqspi_write_setup(struct spi_nor *nor)
>  	struct cqspi_st *cqspi = f_pdata->cqspi;
>  	void __iomem *reg_base = cqspi->iobase;
>  
> +	/* Disable direct access controller */
> +	if (!f_pdata->use_direct_mode) {
> +		reg = readl(reg_base + CQSPI_REG_CONFIG);
> +		reg &= ~CQSPI_REG_CONFIG_ENB_DIR_ACC_CTRL;
> +		writel(reg, reg_base + CQSPI_REG_CONFIG);
> +	}
> +
>  	/* Set opcode. */
>  	reg = nor->program_opcode << CQSPI_REG_WR_INSTR_OPCODE_LSB;
>  	writel(reg, reg_base + CQSPI_REG_WR_INSTR);
> @@ -1328,6 +1336,7 @@ static int cqspi_probe(struct platform_device *pdev)
>  	struct resource *res_ahb;
>  	struct reset_control *rstc, *rstc_ocp;
>  	const struct cqspi_driver_platdata *ddata;
> +	struct cqspi_flash_pdata *f_pdata;
>  	int ret;
>  	int irq;
>  
> @@ -1436,6 +1445,9 @@ static int cqspi_probe(struct platform_device *pdev)
>  		goto probe_setup_failed;
>  	}
>  
> +	if (ddata && (ddata->quirks & CQSPI_DISABLE_DAC_MODE))
> +		f_pdata->use_direct_mode = false;
> +

If you do this here, you will still end up acquiring a DMA channel in
cqspi_request_mmap_dma() (called from cqspi_setup_flash()). So, please
move the check to cqspi_setup_flash().

>  	return ret;
>  probe_setup_failed:
>  	cqspi_controller_enable(cqspi, 0);
> @@ -1510,6 +1522,11 @@ static const struct cqspi_driver_platdata am654_ospi = {
>  	.quirks = CQSPI_NEEDS_WR_DELAY,
>  };
>  
> +static const struct cqspi_driver_platdata intel_lgm_qspi = {
> +	.hwcaps_mask = CQSPI_BASE_HWCAPS_MASK,
> +	.quirks = CQSPI_DISABLE_DAC_MODE,
> +};
> +
>  static const struct of_device_id cqspi_dt_ids[] = {
>  	{
>  		.compatible = "cdns,qspi-nor",
> @@ -1523,6 +1540,10 @@ static const struct of_device_id cqspi_dt_ids[] = {
>  		.compatible = "ti,am654-ospi",
>  		.data = &am654_ospi,
>  	},
> +	{
> +		.compatible = "intel,lgm-qspi",
> +		.data = &intel_lgm_qspi,
> +	},
>  	{ /* end of table */ }
>  };
>  
> 

-- 
Regards
Vignesh