Re: [PATCH] i2c-davinci: Fix use of default platform data if none supplied.
On Sat, Sep 04, 2010 at 12:07:48PM -0400, Michael Williamson wrote:
There is a bug in the i2c-davinci device init routine that attempts
to use default platform data if none is supplied (e.g., is NULL).
This patch fixes the bug.
Signed-off-by: Michael Williamson michael.william...@criticallink.com
---
drivers/i2c/busses/i2c-davinci.c |8 +---
1 files changed, 5 insertions(+), 3 deletions(-)
diff --git a/drivers/i2c/busses/i2c-davinci.c
b/drivers/i2c/busses/i2c-davinci.c
index c87..6d4eeeb 100644
--- a/drivers/i2c/busses/i2c-davinci.c
+++ b/drivers/i2c/busses/i2c-davinci.c
@@ -235,10 +235,12 @@ static void i2c_davinci_calc_clk_dividers(struct
davinci_i2c_dev *dev)
*/
static int i2c_davinci_init(struct davinci_i2c_dev *dev)
{
- struct davinci_i2c_platform_data *pdata = dev-dev-platform_data;
+ struct davinci_i2c_platform_data *pdata;
- if (!pdata)
- pdata = davinci_i2c_platform_data_default;
+ if (!dev-dev-platform_data)
+ dev-dev-platform_data = davinci_i2c_platform_data_default;
+
+ pdata = dev-dev-platform_data;
At first glance this looks like a code shift, however is the platform
data used later in the driver by referencing the device.platform_data
field?
Could you rewrite the header to show this, and if possible note any
actual oops report that has been seen with this.
--
Ben
Q: What's a light-year?
A: One-third less calories than a regular year.
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Re: [PATCH] i2c-davinci: Fix use of default platform data if none supplied.
On 09/21/2010 08:24 PM, Ben Dooks wrote:
On Sat, Sep 04, 2010 at 12:07:48PM -0400, Michael Williamson wrote:
There is a bug in the i2c-davinci device init routine that attempts
to use default platform data if none is supplied (e.g., is NULL).
This patch fixes the bug.
Signed-off-by: Michael Williamson michael.william...@criticallink.com
---
drivers/i2c/busses/i2c-davinci.c |8 +---
1 files changed, 5 insertions(+), 3 deletions(-)
diff --git a/drivers/i2c/busses/i2c-davinci.c
b/drivers/i2c/busses/i2c-davinci.c
index c87..6d4eeeb 100644
--- a/drivers/i2c/busses/i2c-davinci.c
+++ b/drivers/i2c/busses/i2c-davinci.c
@@ -235,10 +235,12 @@ static void i2c_davinci_calc_clk_dividers(struct
davinci_i2c_dev *dev)
*/
static int i2c_davinci_init(struct davinci_i2c_dev *dev)
{
-struct davinci_i2c_platform_data *pdata = dev-dev-platform_data;
+struct davinci_i2c_platform_data *pdata;
-if (!pdata)
-pdata = davinci_i2c_platform_data_default;
+if (!dev-dev-platform_data)
+dev-dev-platform_data = davinci_i2c_platform_data_default;
+
+pdata = dev-dev-platform_data;
At first glance this looks like a code shift, however is the platform
data used later in the driver by referencing the device.platform_data
field?
Yes. The problem call is i2c_davinci_calc_clk_dividers(), which is called
pretty early in the i2c_davinci_init() routine. There is a reference to
pdata-bus_freq without a check to see if pdata is valid. I think my proposed
fix is not the right approach as you have pointed out.
Perhaps a better patch would be (?):
---
diff --git a/drivers/i2c/busses/i2c-davinci.c b/drivers/i2c/busses/i2c-davinci.c
index c87..15d0cea 100644
--- a/drivers/i2c/busses/i2c-davinci.c
+++ b/drivers/i2c/busses/i2c-davinci.c
@@ -195,6 +195,9 @@ static void i2c_davinci_calc_clk_dividers(struct
davinci_i2c_dev *dev)
u32 clkl;
u32 input_clock = clk_get_rate(dev-clk);
+ if (!pdata)
+ pdata = davinci_i2c_platform_data_default;
+
/* NOTE: I2C Clock divider programming info
* As per I2C specs the following formulas provide prescaler
* and low/high divider values
---
Could you rewrite the header to show this, and if possible note any
actual oops report that has been seen with this.
I found this because I was told (while proposing a new platform) to use NULL
as platform data as the parameters I was using matched the default data. I
didn't get an oops, it just hung (it's pretty early in the board init).
Our boot strapper/load resets the DDR where the kernel buffer is, so getting
any oops info is a bit time consuming. The above three lines (and the original
patch) resolved the problem.
I can update the header to indicate a default parameter set if you like. New
patch OK?
-Mike
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[PATCH] i2c-davinci: Fix use of default platform data if none supplied.
There is a bug in the i2c-davinci device init routine that attempts
to use default platform data if none is supplied (e.g., is NULL).
This patch fixes the bug.
Signed-off-by: Michael Williamson michael.william...@criticallink.com
---
drivers/i2c/busses/i2c-davinci.c |8 +---
1 files changed, 5 insertions(+), 3 deletions(-)
diff --git a/drivers/i2c/busses/i2c-davinci.c b/drivers/i2c/busses/i2c-davinci.c
index c87..6d4eeeb 100644
--- a/drivers/i2c/busses/i2c-davinci.c
+++ b/drivers/i2c/busses/i2c-davinci.c
@@ -235,10 +235,12 @@ static void i2c_davinci_calc_clk_dividers(struct
davinci_i2c_dev *dev)
*/
static int i2c_davinci_init(struct davinci_i2c_dev *dev)
{
- struct davinci_i2c_platform_data *pdata = dev-dev-platform_data;
+ struct davinci_i2c_platform_data *pdata;
- if (!pdata)
- pdata = davinci_i2c_platform_data_default;
+ if (!dev-dev-platform_data)
+ dev-dev-platform_data = davinci_i2c_platform_data_default;
+
+ pdata = dev-dev-platform_data;
/* put I2C into reset */
davinci_i2c_reset_ctrl(dev, 0);
--
1.7.0.4
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