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SubjectRE: [PATCH 1/2] i2c: qup: Cleared the error bits in ISR
On 2016-05-11 21:27, Sricharan wrote:
> Hi,
>
>> 1. Current QCOM I2C driver hangs when sending data to address
>> 0x03-0x07
>> in some scenarios. The QUP controller generates invalid write in this
>> case,
>> since these addresses are reserved for different bus formats.
>>
>> 2. Also, the error handling is done by I2C QUP ISR in the case of DMA
>> mode.
>> The state need to be RESET in case of any error for clearing the
>> available
>> data in FIFO, which otherwise leaves the BAM DMA controller in hang
>> state.
>>
>> This patch fixes the above two issues by clearing the error bits from
>> I2C
>> and
>> QUP status in ISR in case of I2C error, QUP error and resets the QUP
>> state
>> to
>> clear the FIFO data.
>>
>> Signed-off-by: Abhishek Sahu <absahu@codeaurora.org>
>> ---
>> drivers/i2c/busses/i2c-qup.c | 14 ++++++++------
>> 1 file changed, 8 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/i2c/busses/i2c-qup.c
>> b/drivers/i2c/busses/i2c-qup.c
>> index
>> 23eaabb..8c2f1bc 100644
>> --- a/drivers/i2c/busses/i2c-qup.c
>> +++ b/drivers/i2c/busses/i2c-qup.c
>> @@ -213,14 +213,16 @@ static irqreturn_t qup_i2c_interrupt(int irq,
>> void
>> *dev)
>> bus_err &= I2C_STATUS_ERROR_MASK;
>> qup_err &= QUP_STATUS_ERROR_FLAGS;
>>
>> - if (qup_err) {
>> - /* Clear Error interrupt */
>> + /* Clear the error bits in QUP_ERROR_FLAGS */
>> + if (qup_err)
>> writel(qup_err, qup->base + QUP_ERROR_FLAGS);
>> - goto done;
>> - }
>>
>> - if (bus_err) {
>> - /* Clear Error interrupt */
>> + /* Clear the error bits in QUP_I2C_STATUS */
>> + if (bus_err)
>> + writel(bus_err, qup->base + QUP_I2C_STATUS);
>> +
>> + /* Reset the QUP State in case of error */
>> + if (qup_err || bus_err) {
>> writel(QUP_RESET_STATE, qup->base + QUP_STATE);
>> goto done;
>> }
> In qup_i2c_xfer and qup_i2c_xfer_v2 state is set to RESET at the
> end, when
> there is no error. So would it be fine if we do it there
> unconditionally ?
>
> Regards,
> Sricharan

RESET the QUP state wouldn't create any issue in the case of multiple
calls.
The existing code also RESET the QUP state for bus_err but it is not
clearing
status bits.

--
Abhishek Sahu

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