Re: Patch "i2c: imx: Fix reset of I2SR_IAL flag" has been added to the 5.8-stable tree

[Christian Eggers <ceggers@arri.de>]

Hi Greg,

the patch below has meanwhile been reverted by Wolfram Sang [1], because it has
been superseded. Although the patch itself is not wrong, you also may want to
revert it in order to avoid conflicts with the next version.

Best regards
Christian

[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=5a02e7c429cb5e082e5d7be6e5b768828014ba70

On Sunday, 11 October 2020, 10:48:33 CEST, gregkh@linuxfoundation.org wrote:
> This is a note to let you know that I've just added the patch titled
> 
>     i2c: imx: Fix reset of I2SR_IAL flag
> 
> to the 5.8-stable tree which can be found at:
>    
> http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=sum
> mary
> 
> The filename of the patch is:
>      i2c-imx-fix-reset-of-i2sr_ial-flag.patch
> and it can be found in the queue-5.8 subdirectory.
> 
> If you, or anyone else, feels it should not be added to the stable tree,
> please let <stable@vger.kernel.org> know about it.
> 
> 
> From fa4d30556883f2eaab425b88ba9904865a4d00f3 Mon Sep 17 00:00:00 2001
> From: Christian Eggers <ceggers@arri.de>
> Date: Wed, 7 Oct 2020 10:45:22 +0200
> Subject: i2c: imx: Fix reset of I2SR_IAL flag
> MIME-Version: 1.0
> Content-Type: text/plain; charset=UTF-8
> Content-Transfer-Encoding: 8bit
> 
> From: Christian Eggers <ceggers@arri.de>
> 
> commit fa4d30556883f2eaab425b88ba9904865a4d00f3 upstream.
> 
> 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
> Signed-off-by: Wolfram Sang <wsa@kernel.org>
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> 
> ---
>  drivers/i2c/busses/i2c-imx.c |   20 +++++++++++++++-----
>  1 file changed, 15 insertions(+), 5 deletions(-)
> 
> --- 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_
>  	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.
> +	 */
> +	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_i
> 
>  		/* 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,
>  	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;
>  	}
> 
> 
> Patches currently in stable-queue which might be from ceggers@arri.de are
> 
> queue-5.8/i2c-imx-fix-reset-of-i2sr_ial-flag.patch