linux-kernel - Re: [PATCH V2] i2c: designware: fix wrong tx/rx fifo for ACPI

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Message-ID: <1481105711.21899.88.camel@linux.intel.com>
Date:   Wed, 07 Dec 2016 12:15:11 +0200
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Tin Huynh <tnhuynh@....com>,
        Jarkko Nikula <jarkko.nikula@...ux.intel.com>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Wolfram Sang <wsa@...-dreams.de>
Cc:     linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-acpi@...r.kernel.org, Loc Ho <lho@....com>,
        Thang Nguyen <tqnguyen@....com>, Phong Vo <pvo@....com>,
        patches@....com
Subject: Re: [PATCH V2] i2c: designware: fix wrong tx/rx fifo for ACPI

On Tue, 2016-12-06 at 14:57 +0700, Tin Huynh wrote:
> ACPI always sets txfifo and rxfifo to 32. This configuration will
> cause problem if the IP core supports a fifo size of less than 32.
> The driver should read the fifo size from the IP and select the 
> smaller one of the two.
> 
> Signed-off-by: Tin Huynh <tnhuynh@....com>
> 

The idea looks good, but see my comment below.

> >dev);
> +	u32 param1, tx_fifo_depth, rx_fifo_depth;
>  	struct dw_i2c_dev *dev;
>  	struct i2c_adapter *adap;
>  	struct resource *mem;
> @@ -246,12 +247,18 @@ static int dw_i2c_plat_probe(struct
> platform_device *pdev)
>  				1000000);
>  	}
>  
> +	param1 = i2c_dw_read_comp_param(dev);
> +	tx_fifo_depth = ((param1 >> 16) & 0xff) + 1;
> +	rx_fifo_depth = ((param1 >> 8)  & 0xff) + 1;
>  	if (!dev->tx_fifo_depth) {
> -		u32 param1 = i2c_dw_read_comp_param(dev);
> -
> -		dev->tx_fifo_depth = ((param1 >> 16) & 0xff) + 1;
> -		dev->rx_fifo_depth = ((param1 >> 8)  & 0xff) + 1;
> +		dev->tx_fifo_depth = tx_fifo_depth;
> +		dev->rx_fifo_depth = rx_fifo_depth;
>  		dev->adapter.nr = pdev->id;
> +	} else if (tx_fifo_depth) {
> +		dev->tx_fifo_depth = min_t(u32, dev->tx_fifo_depth,
> +							tx_fifo_depth
> );
> +		dev->rx_fifo_depth = min_t(u32, dev->rx_fifo_depth,
> +							rx_fifo_dept

Can we move this to a separate function like

static void dw_i2c_set_fifo_size(... *dev, ... id)
{
	u32 param, tx_fifo_depth, rx_fifo_depth;

	param = i2c_dw_read_comp_param(dev);
	tx_fifo_depth = ((param >> 16) & 0xff) + 1;
	rx_fifo_depth = ((param >> 8)  & 0xff) + 1;

 	if (!dev->tx_fifo_depth) {
		dev->tx_fifo_depth = tx_fifo_depth;
		dev->rx_fifo_depth = rx_fifo_depth;
 		dev->adapter.nr = id;
	}

	dev->tx_fifo_depth = min_t(u32, dev->tx_fifo_depth,
tx_fifo_depth);
	dev->rx_fifo_depth = min_t(u32, dev->rx_fifo_depth,
rx_fifo_depth);
}

?

-- 
Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Intel Finland Oy