Hi,
On 31/05/2019 9.54, Peter Ujfalusi wrote:
>
> On 29/05/2019 11.37, Peter Ujfalusi wrote:
>> With the polled parameter the DMA drivers can be tested if they can work
>> correctly when no completion is requested (no DMA_PREP_INTERRUPT and no
>> callback is provided).
>>
>> If polled mode is selected then use dma_sync_wait() to execute the test
>> iteration instead of relying on the completion callback.
>>
>> Signed-off-by: Peter Ujfalusi <peter.ujfalusi@xxxxxx>
>> ---
>> drivers/dma/dmatest.c | 35 ++++++++++++++++++++++++++++-------
>> 1 file changed, 28 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/dma/dmatest.c b/drivers/dma/dmatest.c
>> index b96814a7dceb..088086d041e9 100644
>> --- a/drivers/dma/dmatest.c
>> +++ b/drivers/dma/dmatest.c
>> @@ -75,6 +75,10 @@ static bool norandom;
>> module_param(norandom, bool, 0644);
>> MODULE_PARM_DESC(norandom, "Disable random offset setup (default: random)");
>>
>> +static bool polled;
>> +module_param(polled, bool, S_IRUGO | S_IWUSR);
>> +MODULE_PARM_DESC(polled, "Use polling for completion instead of interrupts");
>> +
>> static bool verbose;
>> module_param(verbose, bool, S_IRUGO | S_IWUSR);
>> MODULE_PARM_DESC(verbose, "Enable \"success\" result messages (default: off)");
>> @@ -113,6 +117,7 @@ struct dmatest_params {
>> bool norandom;
>> int alignment;
>> unsigned int transfer_size;
>> + bool polled;
>> };
>>
>> /**
>> @@ -654,7 +659,10 @@ static int dmatest_func(void *data)
>> /*
>> * src and dst buffers are freed by ourselves below
>> */
>> - flags = DMA_CTRL_ACK | DMA_PREP_INTERRUPT;
>> + if (params->polled)
>> + flags = DMA_CTRL_ACK;
>> + else
>> + flags = DMA_CTRL_ACK | DMA_PREP_INTERRUPT;
>>
>> ktime = ktime_get();
>> while (!kthread_should_stop()
>> @@ -783,8 +791,10 @@ static int dmatest_func(void *data)
>> }
>>
>> done->done = false;
>> - tx->callback = dmatest_callback;
>> - tx->callback_param = done;
>> + if (!params->polled) {
>> + tx->callback = dmatest_callback;
>> + tx->callback_param = done;
>> + }
>> cookie = tx->tx_submit(tx);
>>
>> if (dma_submit_error(cookie)) {
>> @@ -793,12 +803,22 @@ static int dmatest_func(void *data)
>> msleep(100);
>> goto error_unmap_continue;
>> }
>> - dma_async_issue_pending(chan);
>>
>> - wait_event_freezable_timeout(thread->done_wait, done->done,
>> - msecs_to_jiffies(params->timeout));
>> + if (params->polled) {
>> + status = dma_sync_wait(chan, cookie);
>> + dmaengine_terminate_sync(chan);
>> + if (status == DMA_COMPLETE)
>> + done->done = true;
>
> I think the main question is how polling for completion should be
> handled when client does not request for completion interrupt, thus we
> will have no callback in the DMA driver when the transfer is completed.
>
> If DMA_PREP_INTERRUPT is set for the tx_descriptor then the polling will
> wait until the DMA driver internally receives the interrupt that the
> transfer is done and sets the cookie to completed state.
>
> However if DMA_PREP_INTERRUPT is not set, the DMA driver will not get
> notification from the HW that is the transfer is done, the only way to
> know is to check the tx_status and based on the residue (if it is 0 then
> it is done) decide what to tell the client.
>
> Should the client call dmaengine_terminate_* after the polling returned
> unconditionally to free up the descriptor?
This is how omap-dma is handling the polled memcpy support.
> Or client should only call dmaengine_terminate_* in case the polling
> returned with !DMA_COMPLETE and the DMA driver must clean things up
> before returning if the transfer is completed (residue == 0)?
>
>> + } else {
>> + dma_async_issue_pending(chan);
>> +
>> + wait_event_freezable_timeout(thread->done_wait,
>> + done->done,
>> + msecs_to_jiffies(params->timeout));
>>
>> - status = dma_async_is_tx_complete(chan, cookie, NULL, NULL);
>> + status = dma_async_is_tx_complete(chan, cookie, NULL,
>> + NULL);
>> + }
>>
>> if (!done->done) {
>> result("test timed out", total_tests, src->off, dst->off,
>> @@ -1068,6 +1088,7 @@ static void add_threaded_test(struct dmatest_info *info)
>> params->norandom = norandom;
>> params->alignment = alignment;
>> params->transfer_size = transfer_size;
>> + params->polled = polled;
>>
>> request_channels(info, DMA_MEMCPY);
>> request_channels(info, DMA_MEMSET);
>>
>
> - Péter
>
> Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
> Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
>
- Péter
Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
