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Message-ID: <CAJuYYwQ1QmnZ5L_FO3zW3TzfpS=XTDQFf-T14noehQyDzwqDTA@mail.gmail.com>
Date: Mon, 12 Mar 2012 11:38:52 +0530
From: Thomas Abraham <thomas.abraham@...aro.org>
To: Karol Lewandowski <k.lewandowsk@...sung.com>
Cc: ben-linux@...ff.org, m.szyprowski@...sung.com,
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 <kyungmin.park@...sung.com>
Subject: Re: [PATCH 2/2] i2c-s3c2410: Add HDMIPHY quirk for S3C2440
On 9 March 2012 22:34, Karol Lewandowski <k.lewandowsk@...sung.com> wrote:
> From: Tomasz Stanislawski <t.stanislaws@...sung.com>
>
> 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 | 10 +++++-
> drivers/i2c/busses/i2c-s3c2410.c | 34 ++++++++++++++++++++
> 2 files changed, 42 insertions(+), 2 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/i2c/samsung-i2c.txt b/Documentation/devicetree/bindings/i2c/samsung-i2c.txt
> index 38832c7..ac0917c 100644
> --- a/Documentation/devicetree/bindings/i2c/samsung-i2c.txt
> +++ b/Documentation/devicetree/bindings/i2c/samsung-i2c.txt
> @@ -10,14 +10,20 @@ 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
> - 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 on S3C2440 -
> + reduce timeout and reset controller when doing transefers
>
> Example:
>
> diff --git a/drivers/i2c/busses/i2c-s3c2410.c b/drivers/i2c/busses/i2c-s3c2410.c
> index 5b400c6..9f3be51 100644
> --- a/drivers/i2c/busses/i2c-s3c2410.c
> +++ b/drivers/i2c/busses/i2c-s3c2410.c
> @@ -48,6 +48,8 @@
> #define TYPE_BITS 0x000000ff
> #define TYPE_S3C2410 0x00000001
> #define TYPE_S3C2440 0x00000002
> +#define FLAG_HDMIPHY 0x00000100
> +#define FLAG_NO_GPIO 0x00000200
>
> /* i2c controller state */
> enum s3c24xx_i2c_state {
> @@ -449,6 +451,13 @@ 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->type & FLAG_HDMIPHY)
> + timeout = 10;
> +
> while (timeout-- > 0) {
> iicstat = readl(i2c->regs + S3C2410_IICSTAT);
>
> @@ -458,6 +467,15 @@ static int s3c24xx_i2c_set_master(struct s3c24xx_i2c *i2c)
> msleep(1);
> }
>
> + /* hang-up of bus dedicated for HDMIPHY occurred, resetting */
> + if (i2c->type & FLAG_HDMIPHY) {
> + writel(0, i2c->regs + S3C2410_IICCON);
> + writel(0, i2c->regs + S3C2410_IICSTAT);
> + writel(0, i2c->regs + S3C2410_IICDS);
> +
> + return 0;
> + }
> +
> return -ETIMEDOUT;
> }
>
> @@ -739,6 +757,9 @@ static int s3c24xx_i2c_parse_dt_gpio(struct s3c24xx_i2c *i2c)
> {
> int idx, gpio, ret;
>
> + if (i2c->type & FLAG_NO_GPIO)
> + return 0;
> +
> for (idx = 0; idx < 2; idx++) {
> gpio = of_get_gpio(i2c->dev->of_node, idx);
> if (!gpio_is_valid(gpio)) {
> @@ -763,6 +784,10 @@ free_gpio:
> static void s3c24xx_i2c_dt_gpio_free(struct s3c24xx_i2c *i2c)
> {
> unsigned int idx;
> +
> + if (i2c->type & FLAG_NO_GPIO)
> + return;
> +
> for (idx = 0; idx < 2; idx++)
> gpio_free(i2c->gpios[idx]);
> }
> @@ -846,6 +871,12 @@ s3c24xx_i2c_parse_dt(struct device_node *np, struct s3c24xx_i2c *i2c)
> match = of_match_node(&s3c24xx_i2c_match[0], np);
> i2c->type = (unsigned int)match->data;
>
> + if (i2c->type == TYPE_S3C2440 && of_get_property(np, "samsung,i2c-quirk-hdmiphy", NULL))
> + i2c->type |= FLAG_HDMIPHY;
> +
> + if (of_get_property(np, "samsung,i2c-no-gpio", NULL))
> + i2c->type |= FLAG_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",
> @@ -1103,6 +1134,9 @@ static struct platform_device_id s3c24xx_driver_ids[] = {
> }, {
> .name = "s3c2440-i2c",
> .driver_data = TYPE_S3C2440,
> + }, {
> + .name = "s3c2440-hdmiphy-i2c",
> + .driver_data = TYPE_S3C2440 | FLAG_HDMIPHY | FLAG_NO_GPIO,
> }, { },
> };
> MODULE_DEVICE_TABLE(platform, s3c24xx_driver_ids);
> --
> 1.7.9
>
Reviewed-by: Thomas Abraham <thomas.abraham@...aro.org>
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