linux-kernel - Re: [PATCH 3/3] i2c-s3c2410: Add HDMIPHY quirk for S3C2440

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Date:	Tue, 17 Apr 2012 19:40:29 +0200
From:	Wolfram Sang <w.sang@...gutronix.de>
To:	Karol Lewandowski <k.lewandowsk@...sung.com>
Cc:	ben-linux@...ff.org, m.szyprowski@...sung.com,
	thomas.abraham@...aro.org, linux-kernel@...r.kernel.org,
	linux-i2c@...r.kernel.org, devicetree-discuss@...ts.ozlabs.org,
	linux-samsung-soc@...r.kernel.org, t.stanislaws@...sung.com,
	kyungmin.park@...sung.com, broonie@...nsource.wolfsonmicro.com
Subject: Re: [PATCH 3/3] i2c-s3c2410: Add HDMIPHY quirk for S3C2440

Hi,

On Wed, Mar 21, 2012 at 08:11:53PM +0100, Karol Lewandowski wrote:
> This patch adds support for s3c2440 I2C bus controller dedicated HDMIPHY device on
> Exynos4 platform. Some quirks are introduced due to differences between HDMIPHY
> and other I2C controllers on Exynos4.  These differences are:
> - no GPIOs, HDMIPHY is inside the SoC and the controller is connected
>   internally
> - due to unknown reason (probably HW bug in HDMIPHY and/or the controller) a
>   transfer fails to finish. The controller hangs after sending the last byte,
>   the workaround for this bug is resetting the controller after each transfer
> 
> Signed-off-by: Tomasz Stanislawski <t.stanislaws@...sung.com>
> Signed-off-by: Karol Lewandowski <k.lewandowsk@...sung.com>
> Tested-by: Tomasz Stanislawski <t.stanislaws@...sung.com>
> Signed-off-by: Kyungmin Park <kyungmin.park@...sung.com>
> ---
>  .../devicetree/bindings/i2c/samsung-i2c.txt        |   11 +++++-
>  drivers/i2c/busses/i2c-s3c2410.c                   |   35 ++++++++++++++++++++
>  2 files changed, 44 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/i2c/samsung-i2c.txt b/Documentation/devicetree/bindings/i2c/samsung-i2c.txt
> index 38832c7..c6670f9 100644
> --- a/Documentation/devicetree/bindings/i2c/samsung-i2c.txt
> +++ b/Documentation/devicetree/bindings/i2c/samsung-i2c.txt
> @@ -10,14 +10,21 @@ Required properties:
>      region.
>    - interrupts: interrupt number to the cpu.
>    - samsung,i2c-sda-delay: Delay (in ns) applied to data line (SDA) edges.
> -  - gpios: The order of the gpios should be the following: <SDA, SCL>.
> -    The gpio specifier depends on the gpio controller.
>  
>  Optional properties:
> +  - gpios: The order of the gpios should be the following: <SDA, SCL>.
> +    The gpio specifier depends on the gpio controller. Required in all cases
> +    except when "samsung,i2c-no-gpio" is also specified.
> +  - samsung,i2c-no-gpio: input/output lines of the controller are
> +    permanently wired to the respective client, there are no gpio
> +    lines that need to be configured to enable this controller

Can't we just skip this property...


>    - samsung,i2c-slave-addr: Slave address in multi-master enviroment. If not
>      specified, default value is 0.
>    - samsung,i2c-max-bus-freq: Desired frequency in Hz of the bus. If not
>      specified, the default value in Hz is 100000.
> +  - samsung,i2c-quirk-hdmiphy: Quirk for HDMI PHY block found on
> +    Exynos4 platform - reduce timeout and reset controller after each
> +    transfer

... and this one, if we declare a new compatible-entry for exynos4?

>  
>  Example:
>  
> diff --git a/drivers/i2c/busses/i2c-s3c2410.c b/drivers/i2c/busses/i2c-s3c2410.c
> index f7b6a14..e50f523 100644
> --- a/drivers/i2c/busses/i2c-s3c2410.c
> +++ b/drivers/i2c/busses/i2c-s3c2410.c
> @@ -50,6 +50,8 @@ static const struct of_device_id s3c24xx_i2c_match[];
>  
>  /* Treat S3C2410 as baseline hardware, anything else is supported via quirks */
>  #define QUIRK_S3C2440		(1 << 0)
> +#define QUIRK_HDMIPHY		(1 << 1)
> +#define QUIRK_NO_GPIO		(1 << 2)
>  
>  /* i2c controller state */
>  enum s3c24xx_i2c_state {
> @@ -469,6 +471,13 @@ static int s3c24xx_i2c_set_master(struct s3c24xx_i2c *i2c)
>  	unsigned long iicstat;
>  	int timeout = 400;
>  
> +	/* the timeout for HDMIPHY is reduced to 10 ms because
> +	 * the hangup is expected to happen, so waiting 400 ms
> +	 * causes only unnecessary system hangup
> +	 */
> +	if (i2c->quirks & QUIRK_HDMIPHY)
> +		timeout = 10;
> +
>  	while (timeout-- > 0) {
>  		iicstat = readl(i2c->regs + S3C2410_IICSTAT);
>  
> @@ -478,6 +487,15 @@ static int s3c24xx_i2c_set_master(struct s3c24xx_i2c *i2c)
>  		msleep(1);
>  	}
>  
> +	/* hang-up of bus dedicated for HDMIPHY occurred, resetting */
> +	if (i2c->quirks & QUIRK_HDMIPHY) {
> +		writel(0, i2c->regs + S3C2410_IICCON);
> +		writel(0, i2c->regs + S3C2410_IICSTAT);
> +		writel(0, i2c->regs + S3C2410_IICDS);
> +
> +		return 0;
> +	}
> +
>  	return -ETIMEDOUT;
>  }
>  
> @@ -759,6 +777,9 @@ static int s3c24xx_i2c_parse_dt_gpio(struct s3c24xx_i2c *i2c)
>  {
>  	int idx, gpio, ret;
>  
> +	if (i2c->quirks & QUIRK_NO_GPIO)
> +		return 0;
> +
>  	for (idx = 0; idx < 2; idx++) {
>  		gpio = of_get_gpio(i2c->dev->of_node, idx);
>  		if (!gpio_is_valid(gpio)) {
> @@ -783,6 +804,10 @@ free_gpio:
>  static void s3c24xx_i2c_dt_gpio_free(struct s3c24xx_i2c *i2c)
>  {
>  	unsigned int idx;
> +
> +	if (i2c->quirks & QUIRK_NO_GPIO)
> +		return;
> +
>  	for (idx = 0; idx < 2; idx++)
>  		gpio_free(i2c->gpios[idx]);
>  }
> @@ -859,6 +884,13 @@ s3c24xx_i2c_parse_dt(struct device_node *np, struct s3c24xx_i2c *i2c)
>  		return;
>  
>  	pdata->bus_num = -1; /* i2c bus number is dynamically assigned */
> +
> +	if (of_get_property(np, "samsung,i2c-quirk-hdmiphy", NULL))
> +		i2c->quirks |= QUIRK_HDMIPHY;
> +
> +	if (of_get_property(np, "samsung,i2c-no-gpio", NULL))
> +		i2c->quirks |= QUIRK_NO_GPIO;
> +
>  	of_property_read_u32(np, "samsung,i2c-sda-delay", &pdata->sda_delay);
>  	of_property_read_u32(np, "samsung,i2c-slave-addr", &pdata->slave_addr);
>  	of_property_read_u32(np, "samsung,i2c-max-bus-freq",
> @@ -1116,6 +1148,9 @@ static struct platform_device_id s3c24xx_driver_ids[] = {
>  	}, {
>  		.name		= "s3c2440-i2c",
>  		.driver_data	= QUIRK_S3C2440,
> +	}, {
> +		.name		= "s3c2440-hdmiphy-i2c",
> +		.driver_data	= QUIRK_S3C2440 | QUIRK_HDMIPHY | QUIRK_NO_GPIO,
>  	}, { },
>  };
>  MODULE_DEVICE_TABLE(platform, s3c24xx_driver_ids);
> -- 
> 1.7.9
> 

-- 
Pengutronix e.K.                           | Wolfram Sang                |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |

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