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Date:   Tue, 3 Nov 2020 21:39:42 +0530
From:   Pratyush Yadav <p.yadav@ti.com>
To:     "Ramuthevar,Vadivel MuruganX" 
        <vadivel.muruganx.ramuthevar@linux.intel.com>
CC:     <broonie@kernel.org>, <vigneshr@ti.com>,
        <tudor.ambarus@microchip.com>, <linux-kernel@vger.kernel.org>,
        <linux-spi@vger.kernel.org>, <robh+dt@kernel.org>,
        <devicetree@vger.kernel.org>, <miquel.raynal@bootlin.com>,
        <simon.k.r.goldschmidt@gmail.com>, <dinguyen@kernel.org>,
        <richard@nod.at>, <cheol.yong.kim@intel.com>,
        <qi-ming.wu@intel.com>
Subject: Re: [PATCH v6 2/6] spi: cadence-quadspi: Disable the DAC for Intel
 LGM SoC
Message-ID: <20201103160834.mfbasmmlgsptnl5l@ti.com>
References: <20201030053153.5319-1-vadivel.muruganx.ramuthevar@linux.intel.com>
 <20201030053153.5319-3-vadivel.muruganx.ramuthevar@linux.intel.com>
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On 30/10/20 01:31PM, Ramuthevar,Vadivel MuruganX wrote:
> From: Ramuthevar Vadivel Murugan <vadivel.muruganx.ramuthevar@linux.intel.com>
> 
> On Intel Lightning Mountain(LGM) SoCs QSPI controller do not use
> Direct Access Controller(DAC).
> 
> This patch adds a quirk to disable the Direct Access Controller
> for data transfer instead it uses indirect data transfer.
> 
> Signed-off-by: Ramuthevar Vadivel Murugan <vadivel.muruganx.ramuthevar@linux.intel.com>
> ---
>  drivers/spi/spi-cadence-quadspi.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/drivers/spi/spi-cadence-quadspi.c b/drivers/spi/spi-cadence-quadspi.c
> index d7b10c46fa70..6d6f7c440ece 100644
> --- a/drivers/spi/spi-cadence-quadspi.c
> +++ b/drivers/spi/spi-cadence-quadspi.c
> @@ -1107,6 +1107,13 @@ static void cqspi_controller_init(struct cqspi_st *cqspi)
>  	writel(reg, cqspi->iobase + CQSPI_REG_CONFIG);
>  
>  	cqspi_controller_enable(cqspi, 1);
> +
> +	/* Disable direct access controller */
> +	if (!cqspi->use_direct_mode) {
> +		reg = readl(cqspi->iobase + CQSPI_REG_CONFIG);
> +		reg &= ~CQSPI_REG_CONFIG_ENB_DIR_ACC_CTRL;
> +		writel(reg, cqspi->iobase + CQSPI_REG_CONFIG);
> +	}

You did not address my comment here from last time around [0]. Please 
replace this hunk with the one below and test it. Also mention in the 
commit message that the DAC bit resets to 1 so there is no need to 
explicitly set it.

--- 8< ---
diff --git a/drivers/spi/spi-cadence-quadspi.c 
b/drivers/spi/spi-cadence-quadspi.c
index d7ad8b198a11..d2c5d448a944 100644
--- a/drivers/spi/spi-cadence-quadspi.c
+++ b/drivers/spi/spi-cadence-quadspi.c
@@ -2156,10 +2156,12 @@ static void cqspi_controller_init(struct cqspi_st *cqspi)
 	writel(cqspi->fifo_depth * cqspi->fifo_width / 8,
 	       cqspi->iobase + CQSPI_REG_INDIRECTWRWATERMARK);
 
-	/* Enable Direct Access Controller */
-	reg = readl(cqspi->iobase + CQSPI_REG_CONFIG);
-	reg |= CQSPI_REG_CONFIG_ENB_DIR_ACC_CTRL;
-	writel(reg, cqspi->iobase + CQSPI_REG_CONFIG);
+	/* Disable Direct Access Controller */
+	if (!cqspi->use_dac_mode) {
+		reg = readl(cqspi->iobase + CQSPI_REG_CONFIG);
+		reg &= ~CQSPI_REG_CONFIG_ENB_DIR_ACC_CTRL;
+		writel(reg, cqspi->iobase + CQSPI_REG_CONFIG);
+	}
 
 	cqspi_controller_enable(cqspi, 1);
 }
--- >8 ---

Same disclaimer as last time: not tested at all.

[0] https://lore.kernel.org/linux-spi/20201022090146.2uj5gfx73dsfumjl@ti.com/

PS: Please Cc me in the next revision. I missed 3 revisions in between 
because I'm not subscribed to this list. Otherwise I would have sent 
this much sooner :-)

>  }
>  
>  static int cqspi_request_mmap_dma(struct cqspi_st *cqspi)
> @@ -1388,6 +1395,10 @@ static const struct cqspi_driver_platdata am654_ospi = {
>  	.quirks = CQSPI_NEEDS_WR_DELAY,
>  };
>  
> +static const struct cqspi_driver_platdata intel_lgm_qspi = {
> +	.quirks = CQSPI_DISABLE_DAC_MODE,
> +};
> +
>  static const struct of_device_id cqspi_dt_ids[] = {
>  	{
>  		.compatible = "cdns,qspi-nor",
> @@ -1403,6 +1414,7 @@ static const struct of_device_id cqspi_dt_ids[] = {
>  	},
>  	{
>  		.compatible = "intel,lgm-qspi",
> +		.data = &intel_lgm_qspi,
>  	},
>  	{ /* end of table */ }
>  };
> -- 
> 2.11.0
> 

-- 
Regards,
Pratyush Yadav
Texas Instruments India