On 28/07/15 12:46, Sifan Naeem wrote:
> Hi James,
>
>> -----Original Message-----
>> From: James Hogan
>> Sent: 28 July 2015 12:36
>> To: Sifan Naeem; Wolfram Sang; linux-i2c@xxxxxxxxxxxxxxx
>> Cc: Stable kernel (v3.19+)
>> Subject: Re: [PATCH 5/8] i2c: img-scb: reset interrupts in img_i2c_soft_reset
>>
>> On 27/07/15 12:47, Sifan Naeem wrote:
>>> Reset interrupt enable register and clear any generated interrupts to
>>> make sure of a clean slate after a soft reset. Not doing so might
>>> leave unhandle line status or generated interrupts which can cause
>>> issues when handling new transfers.
>>
>> That already happens after the call to img_i2c_soft_reset, you've just moved
>> it to while the clock is off and the block is in soft reset. So are you saying its
>> important for interrupts and the various event bits to be clear before taking it
>> out of reset and enabling the clock? TBH I'm confused how they could do any
>> harm.
>>
> In " [PATCH 7/8] i2c: img-scb: improve transaction complete handle "
> img_i2c_soft_reset is added to img_i2c_complete_transaction, this will
> be useful in this scenario, not necessarily for when initialising the
> block.
Okay, in that case you should clarify in the commit message that it is
in preparation for later patches, rather than fixing an existing problem.
Cheers
James
>
> Thanks
> Sifan
>> Cheers
>> James
>>
>>>
>>> Fixes: 27bce4 ("i2c: img-scb: Add Imagination Technologies I2C SCB
>>> driver")
>>> Signed-off-by: Sifan Naeem <sifan.naeem@xxxxxxxxxx>
>>> Cc: Stable kernel (v3.19+) <stable@xxxxxxxxxxxxxxx>
>>> ---
>>> drivers/i2c/busses/i2c-img-scb.c | 26 ++++++++++++++------------
>>> 1 file changed, 14 insertions(+), 12 deletions(-)
>>>
>>> diff --git a/drivers/i2c/busses/i2c-img-scb.c
>>> b/drivers/i2c/busses/i2c-img-scb.c
>>> index 51a5be8..653f9bd 100644
>>> --- a/drivers/i2c/busses/i2c-img-scb.c
>>> +++ b/drivers/i2c/busses/i2c-img-scb.c
>>> @@ -507,8 +507,22 @@ static void img_i2c_soft_reset(struct img_i2c
>>> *i2c) {
>>> i2c->t_halt = false;
>>> img_i2c_writel(i2c, SCB_CONTROL_REG, 0);
>>> +
>>> + /* Disable all interrupts */
>>> + img_i2c_writel(i2c, SCB_INT_MASK_REG, 0);
>>> +
>>> + /* Clear all interrupts */
>>> + img_i2c_writel(i2c, SCB_INT_CLEAR_REG, ~0);
>>> +
>>> + /* Clear the scb_line_status events */
>>> + img_i2c_writel(i2c, SCB_CLEAR_REG, ~0);
>>> +
>>> img_i2c_writel(i2c, SCB_CONTROL_REG,
>>> SCB_CONTROL_CLK_ENABLE |
>> SCB_CONTROL_SOFT_RESET);
>>> +
>>> + /* Enable interrupts */
>>> + img_i2c_switch_mode(i2c, MODE_INACTIVE);
>>> + img_i2c_writel(i2c, SCB_INT_MASK_REG, i2c->int_enable);
>>> }
>>>
>>> /* enable or release transaction halt for control of repeated starts
>>> */ @@ -1242,18 +1256,6 @@ static int img_i2c_init(struct img_i2c *i2c)
>>> /* Take module out of soft reset and enable clocks */
>>> img_i2c_soft_reset(i2c);
>>>
>>> - /* Disable all interrupts */
>>> - img_i2c_writel(i2c, SCB_INT_MASK_REG, 0);
>>> -
>>> - /* Clear all interrupts */
>>> - img_i2c_writel(i2c, SCB_INT_CLEAR_REG, ~0);
>>> -
>>> - /* Clear the scb_line_status events */
>>> - img_i2c_writel(i2c, SCB_CLEAR_REG, ~0);
>>> -
>>> - /* Enable interrupts */
>>> - img_i2c_writel(i2c, SCB_INT_MASK_REG, i2c->int_enable);
>>> -
>>> /* Perform a synchronous sequence to reset the bus */
>>> ret = img_i2c_reset_bus(i2c);
>>>
>>>
>
Attachment:
signature.asc
Description: OpenPGP digital signature