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    SubjectRe: [PATCH 2/2] i2c-s3c2410: Add HDMIPHY quirk for S3C2440
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    On 9 March 2012 22:34, Karol Lewandowski <k.lewandowsk@samsung.com> wrote:
    > From: Tomasz Stanislawski <t.stanislaws@samsung.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@samsung.com>
    > Signed-off-by: Karol Lewandowski <k.lewandowsk@samsung.com>
    > Tested-by: Tomasz Stanislawski <t.stanislaws@samsung.com>
    > Signed-off-by: Kyungmin Park <kyungmin.park@samsung.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@linaro.org>
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