Subject: [PATCH 2/2] i2c: mv64xxx: Fix bus hang on A0 version of the Armada XP SoCs

From: [email-masked] (Gregory CLEMENT)
Date: Fri, 03 Jan 2014 09:48:19 +0100

On 02/01/2014 19:41, Wolfram Sang wrote:
> On Thu, Jan 02, 2014 at 01:28:22PM -0500, Jason Cooper wrote:
>> Wolfram,
>>
>> On Thu, Jan 02, 2014 at 05:01:16PM +0100, Gregory CLEMENT wrote:
>>> The first variants of Armada XP SoCs (A0 stepping) have issues related
>>> to the i2c controller which prevent to use the offload mechanism and
>>> lead to a kernel hang during boot.
>>>
>>> The driver now check the revision of the SoC. If the revision is not
>>> more recent than the A0 or if the driver can't get the SoC revision
>>> then it disables the offload mechanism.
>>>
>>> Cc: stable at vger.kernel.org
>>> Signed-off-by: Gregory CLEMENT <[email-masked]>
>>> ---
>>>  drivers/i2c/busses/i2c-mv64xxx.c | 11 ++++++++++-
>>>  1 file changed, 10 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/i2c/busses/i2c-mv64xxx.c b/drivers/i2c/busses/i2c-mv64xxx.c
>>> index 8be7e42aa4de..089a3663ad86 100644
>>> --- a/drivers/i2c/busses/i2c-mv64xxx.c
>>> +++ b/drivers/i2c/busses/i2c-mv64xxx.c
>>> @@ -24,6 +24,7 @@
>>>  #include <linux/clk.h>
>>>  #include <linux/err.h>
>>>  #include <linux/delay.h>
>>> +#include <linux/mvebu-soc-id.h>
>>>  
>>>  #define MV64XXX_I2C_ADDR_ADDR(val)			((val & 0x7f) << 1)
>>>  #define MV64XXX_I2C_BAUD_DIV_N(val)			(val & 0x7)
>>> @@ -779,8 +780,16 @@ mv64xxx_of_config(struct mv64xxx_i2c_data *drv_data,
>>>  	 * Transaction Generator support and the errata fix.
>>>  	 */
>>>  	if (of_device_is_compatible(np, "marvell,mv78230-i2c")) {
>>> -		drv_data->offload_enabled = true;
>>> +		u32 dev, rev;
>>> +
>>>  		drv_data->errata_delay = true;
>>> +		/*
>>> +		 * Only revison more recent than A0 support offload
>>> +		 * mechanism. In case we can't get the SoC revision
>>> +		 * weplay safe and we don't enable it
>>> +		 */
>>> +		if (!mvebu_get_soc_id(&rev, &dev) && (dev > MV78XX0_A0_REV))
> 
> Very minor nits:
> 
> I'd prefer (mvebu_get_soc_id == 0) here, since !mvebu_get_soc_id can
> easily be read as "if not get soc id" which leads to the assumption the
> function failed. 

yes fair enough

>And the parantheses around the second comparison are
> superfluous.
> 

I know but I found it clearer with parenthesis but I can remove them.

>>> +			drv_data->offload_enabled = true;
>>
>> Since this depends on arch-specific code in the previous patch, I'd like
>> to keep the two of them together in a topic branch.  Would you prefer to
>> take both with my Ack, or vice-versa?  I'm fine either way.
> 
> I'd think you better take it:
> 
> Acked-by: Wolfram Sang <[email-masked]>
> 

I am going to resubmit a series with the change you asked and your acked-by

-- 
Gregory Clement, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com