[PATCH] ARM: DaVinci: I2C: enable zero-length transfer hack

[PATCH] ARM: DaVinci: I2C: enable zero-length transfer hack

[Troy Kisky]

From: Vladimir Barinov <vbarinov-hkdhdckH98+B+jHODAdFcQ@public.gmane.org>

ARM: DaVinci: I2C: enable zero-length transfer hack

Signed-off-by: Vladimir Barinov <vbarinov-hkdhdckH98+B+jHODAdFcQ@public.gmane.org>
Signed-off-by: Kevin Hilman <khilman-Igf4POYTYCDQT0dZR+AlfA@public.gmane.org>
---
 drivers/i2c/busses/i2c-davinci.c |   24 ++++++++++++++++++++++++
 1 files changed, 24 insertions(+), 0 deletions(-)

diff --git a/drivers/i2c/busses/i2c-davinci.c b/drivers/i2c/busses/i2c-davinci.c
index 6767988..f348ee0 100644
--- a/drivers/i2c/busses/i2c-davinci.c
+++ b/drivers/i2c/busses/i2c-davinci.c
@@ -41,6 +41,11 @@
 
 #include <asm/arch/i2c.h>
 
+/* Hack to enable zero length transfers and smbus quick until clean fix
+ * is available
+ */
+#define DAVINCI_HACK
+
 /* ----- global defines ----------------------------------------------- */
 
 #define DAVINCI_I2C_TIMEOUT	(1*HZ)
@@ -236,9 +241,14 @@ i2c_davinci_xfer_msg(struct i2c_adapter *adap, struct i2c_msg *msg, int stop)
 	u32 stat;
 	u16 w;
 	int r;
+#ifdef DAVINCI_HACK
+	u8 zero_byte = 0;
+#endif
 
+#ifndef DAVINCI_HACK
 	if (msg->len == 0)
 		return -EINVAL;
+#endif
 
 	if (!pdata)
 		pdata = &davinci_i2c_platform_data_default;
@@ -249,8 +259,18 @@ i2c_davinci_xfer_msg(struct i2c_adapter *adap, struct i2c_msg *msg, int stop)
 	/* set the slave address */
 	davinci_i2c_write_reg(dev, DAVINCI_I2C_SAR_REG, msg->addr);
 
+#ifndef DAVINCI_HACK
 	dev->buf = msg->buf;
 	dev->buf_len = msg->len;
+#else
+	if (msg->len == 0) {
+		dev->buf = &zero_byte;
+		dev->buf_len = 1;
+	} else {
+		dev->buf = msg->buf;
+		dev->buf_len = msg->len;
+	}
+#endif
 
 	davinci_i2c_write_reg(dev, DAVINCI_I2C_CNT_REG, dev->buf_len);
 
@@ -349,7 +369,11 @@ i2c_davinci_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
 
 static u32 i2c_davinci_func(struct i2c_adapter *adap)
 {
+#ifndef DAVINCI_HACK
 	return I2C_FUNC_I2C | (I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_QUICK);
+#else
+	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
+#endif
 }
 
 /*
-- 
1.5.4


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Re: [PATCH] ARM: DaVinci: I2C: enable zero-length transfer hack

[Kevin Hilman]

Troy Kisky <troy.kisky-Q5RJGjKts06CY9SHAMCTRUEOCMrvLtNR@public.gmane.org> writes:

> From: Vladimir Barinov <vbarinov-hkdhdckH98+B+jHODAdFcQ@public.gmane.org>
>
> ARM: DaVinci: I2C: enable zero-length transfer hack

Troy,

Please send your other DaVinci i2c fixes and cleanups, but leave this
one out for now.  This is a temporary hack.

Kevin

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Re: [PATCH] ARM: DaVinci: I2C: enable zero-length transfer hack

[Jean Delvare]

Hi Troy,

On Mon, 11 Feb 2008 18:59:47 -0700, Troy Kisky wrote:
> From: Vladimir Barinov <vbarinov-hkdhdckH98+B+jHODAdFcQ@public.gmane.org>
> 
> ARM: DaVinci: I2C: enable zero-length transfer hack
> 
> Signed-off-by: Vladimir Barinov <vbarinov-hkdhdckH98+B+jHODAdFcQ@public.gmane.org>
> Signed-off-by: Kevin Hilman <khilman-Igf4POYTYCDQT0dZR+AlfA@public.gmane.org>
> ---
>  drivers/i2c/busses/i2c-davinci.c |   24 ++++++++++++++++++++++++
>  1 files changed, 24 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-davinci.c b/drivers/i2c/busses/i2c-davinci.c
> index 6767988..f348ee0 100644
> --- a/drivers/i2c/busses/i2c-davinci.c
> +++ b/drivers/i2c/busses/i2c-davinci.c
> @@ -41,6 +41,11 @@
>  
>  #include <asm/arch/i2c.h>
>  
> +/* Hack to enable zero length transfers and smbus quick until clean fix
> + * is available
> + */
> +#define DAVINCI_HACK
> +
>  /* ----- global defines ----------------------------------------------- */
>  
>  #define DAVINCI_I2C_TIMEOUT	(1*HZ)
> @@ -236,9 +241,14 @@ i2c_davinci_xfer_msg(struct i2c_adapter *adap, struct i2c_msg *msg, int stop)
>  	u32 stat;
>  	u16 w;
>  	int r;
> +#ifdef DAVINCI_HACK
> +	u8 zero_byte = 0;
> +#endif
>  
> +#ifndef DAVINCI_HACK
>  	if (msg->len == 0)
>  		return -EINVAL;
> +#endif
>  
>  	if (!pdata)
>  		pdata = &davinci_i2c_platform_data_default;
> @@ -249,8 +259,18 @@ i2c_davinci_xfer_msg(struct i2c_adapter *adap, struct i2c_msg *msg, int stop)
>  	/* set the slave address */
>  	davinci_i2c_write_reg(dev, DAVINCI_I2C_SAR_REG, msg->addr);
>  
> +#ifndef DAVINCI_HACK
>  	dev->buf = msg->buf;
>  	dev->buf_len = msg->len;
> +#else
> +	if (msg->len == 0) {
> +		dev->buf = &zero_byte;
> +		dev->buf_len = 1;
> +	} else {
> +		dev->buf = msg->buf;
> +		dev->buf_len = msg->len;
> +	}
> +#endif
>  
>  	davinci_i2c_write_reg(dev, DAVINCI_I2C_CNT_REG, dev->buf_len);
>  
> @@ -349,7 +369,11 @@ i2c_davinci_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
>  
>  static u32 i2c_davinci_func(struct i2c_adapter *adap)
>  {
> +#ifndef DAVINCI_HACK
>  	return I2C_FUNC_I2C | (I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_QUICK);
> +#else
> +	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
> +#endif
>  }
>  
>  /*

Nack. If the hardware doesn't support zero-byte transactions, it
doesn't support them, period. The new i2c framework makes it very easy
to live without these transactions anyway.

-- 
Jean Delvare

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