Re: [PATCH v5 1/3] i2c: imx: Fix reset of I2SR_IAL flag

From: Oleksij Rempel <o.rempel@pengutronix.de>
To: Christian Eggers <ceggers@arri.de>
Cc: "Shawn Guo" <shawnguo@kernel.org>,
	"Sascha Hauer" <s.hauer@pengutronix.de>,
	linux-kernel@vger.kernel.org,
	"Krzysztof Kozlowski" <krzk@kernel.org>,
	"Oleksij Rempel" <linux@rempel-privat.de>,
	"David Laight" <David.Laight@ACULAB.COM>,
	"NXP Linux Team" <linux-imx@nxp.com>,
	"Pengutronix Kernel Team" <kernel@pengutronix.de>,
	"Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>,
	stable@vger.kernel.org, "Fabio Estevam" <festevam@gmail.com>,
	linux-arm-kernel@lists.infradead.org, linux-i2c@vger.kernel.org
Subject: Re: [PATCH v5 1/3] i2c: imx: Fix reset of I2SR_IAL flag
Date: Fri, 9 Oct 2020 09:11:32 +0200	[thread overview]
Message-ID: <20201009071132.GA817@pengutronix.de> (raw)
In-Reply-To: <20201007084524.10835-2-ceggers@arri.de>

Hi Christian,

On Wed, Oct 07, 2020 at 10:45:22AM +0200, Christian Eggers wrote:
> According to the "VFxxx Controller Reference Manual" (and the comment
> block starting at line 97), Vybrid requires writing a one for clearing
> an interrupt flag. Syncing the method for clearing I2SR_IIF in
> i2c_imx_isr().
> 
> Signed-off-by: Christian Eggers <ceggers@arri.de>
> Fixes: 4b775022f6fd ("i2c: imx: add struct to hold more configurable quirks")
> Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> Cc: stable@vger.kernel.org
> ---
>  drivers/i2c/busses/i2c-imx.c | 20 +++++++++++++++-----
>  1 file changed, 15 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
> index 0ab5381aa012..cbdcab73a055 100644
> --- a/drivers/i2c/busses/i2c-imx.c
> +++ b/drivers/i2c/busses/i2c-imx.c
> @@ -412,6 +412,19 @@ static void i2c_imx_dma_free(struct imx_i2c_struct *i2c_imx)
>  	dma->chan_using = NULL;
>  }
>  
> +static void i2c_imx_clear_irq(struct imx_i2c_struct *i2c_imx, unsigned int bits)
> +{
> +	unsigned int temp;
> +
> +	/*
> +	 * i2sr_clr_opcode is the value to clear all interrupts. Here we want to
> +	 * clear only <bits>, so we write ~i2sr_clr_opcode with just <bits>
> +	 * toggled. This is required because i.MX needs W1C and Vybrid uses W0C.
> +	 */

This comment need correction. The i.MX needs W0C and Vybrid uses W1C 

> +	temp = ~i2c_imx->hwdata->i2sr_clr_opcode ^ bits;
> +	imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2SR);
> +}
> +
>  static int i2c_imx_bus_busy(struct imx_i2c_struct *i2c_imx, int for_busy, bool atomic)
>  {
>  	unsigned long orig_jiffies = jiffies;
> @@ -424,8 +437,7 @@ static int i2c_imx_bus_busy(struct imx_i2c_struct *i2c_imx, int for_busy, bool a
>  
>  		/* check for arbitration lost */
>  		if (temp & I2SR_IAL) {
> -			temp &= ~I2SR_IAL;
> -			imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2SR);
> +			i2c_imx_clear_irq(i2c_imx, I2SR_IAL);
>  			return -EAGAIN;
>  		}
>  
> @@ -623,9 +635,7 @@ static irqreturn_t i2c_imx_isr(int irq, void *dev_id)
>  	if (temp & I2SR_IIF) {
>  		/* save status register */
>  		i2c_imx->i2csr = temp;
> -		temp &= ~I2SR_IIF;
> -		temp |= (i2c_imx->hwdata->i2sr_clr_opcode & I2SR_IIF);
> -		imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2SR);
> +		i2c_imx_clear_irq(i2c_imx, I2SR_IIF);
>  		wake_up(&i2c_imx->queue);
>  		return IRQ_HANDLED;
>  	}
> -- 

Otherwise

Acked-by: Oleksij Rempel <o.rempel@pengutronix.de> 

Regards,
Oleksij
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