Re: [PATCH v2 1/2] hwtracing: hisi_ptt: Propagate DMA reset timeout in trace_start()

[Sizhe Liu <liusizhe5@huawei.com>]

On 2026/4/17 1:25, Yicong Yang wrote:
> +cc Suzuki and Sizhe..
>
> On 2026/4/15 01:25, Pradhan, Sanman wrote:
>> From: Sanman Pradhan <psanman@juniper.net>
>>
>> hisi_ptt_wait_dma_reset_done() discards the return value of
>> readl_poll_timeout_atomic(). If the DMA engine does not complete its
>> reset within the timeout, hisi_ptt_trace_start() proceeds to start
>> tracing regardless.
>>
>> Return a bool from hisi_ptt_wait_dma_reset_done(), consistent with the
>> other wait helpers in this driver. On timeout, log an error, de-assert
>> the reset bit, and return -ETIMEDOUT. Move ctrl->started to the
>> successful path so a failed start does not leave the trace marked as
>> active.
>>
>> Fixes: ff0de066b463 ("hwtracing: hisi_ptt: Add trace function support for HiSilicon PCIe Tune and Trace device")
>> Cc: stable@vger.kernel.org
>> Signed-off-by: Sanman Pradhan <psanman@juniper.net>
> looks good to me.
>
> Reviewed-by: Yicong Yang <yangyccccc@gmail.com>
>
> I see the Suzuki has sent out the PR for 7.1, so this may wait after the merge window...
>
> thanks.

Looks good to me, thanks.

Reviewed-by: Sizhe Liu <liusizhe5@huawei.com>

>> ---
>> v2:
>>    - Return bool for consistency with other wait helpers
>>    - Add pci_err() on timeout
>>    - De-assert RST before returning on timeout
>>    - Move ctrl->started to the successful path
>>
>>   drivers/hwtracing/ptt/hisi_ptt.c | 20 +++++++++++++-------
>>   1 file changed, 13 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/hwtracing/ptt/hisi_ptt.c b/drivers/hwtracing/ptt/hisi_ptt.c
>> index 94c371c491357..b5d851281fbf0 100644
>> --- a/drivers/hwtracing/ptt/hisi_ptt.c
>> +++ b/drivers/hwtracing/ptt/hisi_ptt.c
>> @@ -171,13 +171,13 @@ static bool hisi_ptt_wait_trace_hw_idle(struct hisi_ptt *hisi_ptt)
>>   					  HISI_PTT_WAIT_TRACE_TIMEOUT_US);
>>   }
>>   
>> -static void hisi_ptt_wait_dma_reset_done(struct hisi_ptt *hisi_ptt)
>> +static bool hisi_ptt_wait_dma_reset_done(struct hisi_ptt *hisi_ptt)
>>   {
>>   	u32 val;
>>   
>> -	readl_poll_timeout_atomic(hisi_ptt->iobase + HISI_PTT_TRACE_WR_STS,
>> -				  val, !val, HISI_PTT_RESET_POLL_INTERVAL_US,
>> -				  HISI_PTT_RESET_TIMEOUT_US);
>> +	return !readl_poll_timeout_atomic(hisi_ptt->iobase + HISI_PTT_TRACE_WR_STS,
>> +					  val, !val, HISI_PTT_RESET_POLL_INTERVAL_US,
>> +					  HISI_PTT_RESET_TIMEOUT_US);
>>   }
>>   
>>   static void hisi_ptt_trace_end(struct hisi_ptt *hisi_ptt)
>> @@ -202,14 +202,18 @@ static int hisi_ptt_trace_start(struct hisi_ptt *hisi_ptt)
>>   		return -EBUSY;
>>   	}
>>   
>> -	ctrl->started = true;
>> -
>>   	/* Reset the DMA before start tracing */
>>   	val = readl(hisi_ptt->iobase + HISI_PTT_TRACE_CTRL);
>>   	val |= HISI_PTT_TRACE_CTRL_RST;
>>   	writel(val, hisi_ptt->iobase + HISI_PTT_TRACE_CTRL);
>>   
>> -	hisi_ptt_wait_dma_reset_done(hisi_ptt);
>> +	if (!hisi_ptt_wait_dma_reset_done(hisi_ptt)) {
>> +		pci_err(hisi_ptt->pdev, "timed out waiting for DMA reset\n");
>> +		val = readl(hisi_ptt->iobase + HISI_PTT_TRACE_CTRL);
>> +		val &= ~HISI_PTT_TRACE_CTRL_RST;
>> +		writel(val, hisi_ptt->iobase + HISI_PTT_TRACE_CTRL);
>> +		return -ETIMEDOUT;
>> +	}
>>   
>>   	val = readl(hisi_ptt->iobase + HISI_PTT_TRACE_CTRL);
>>   	val &= ~HISI_PTT_TRACE_CTRL_RST;
>> @@ -234,6 +238,8 @@ static int hisi_ptt_trace_start(struct hisi_ptt *hisi_ptt)
>>   	if (!hisi_ptt->trace_ctrl.is_port)
>>   		val |= HISI_PTT_TRACE_CTRL_FILTER_MODE;
>>   
>> +	ctrl->started = true;
>> +
>>   	/* Start the Trace */
>>   	val |= HISI_PTT_TRACE_CTRL_EN;
>>   	writel(val, hisi_ptt->iobase + HISI_PTT_TRACE_CTRL);