TDA4VH-Q1: How many buffer do DSS edp display holds ?

Hello Kamalakkannan,

Could you please tell me what OS this is implemented in?

-Josue

Because it needs something to display in case application misses to provide the buffer, so it keeps one buffer with itself. 

Regards,

Brijesh

Hi Brijesh

yes for 1 buffer hold with itself is ok .

but when we are calling Fvid2_queue() and Fvid2_dequeue() simultaneously,  first 2 time the Fvid2_dequeue() return (- 8)  value and then from 3rd time onward it return (0)   , why this is happening ?

hence the first 2 buffer are with itself out of 3 buffer ....

some logs are below for reference  

Thanks 

Freertos 

Hi , 

Please look in to it , little urgent .

Thanks 

Hi,

but are you waiting for the callback function from the driver before calling dequeue? Dequeue can only be called if there is some buffer available in the driver for the dequeue and this driver indicates by calling the callback, so ideally you should wait for this callback and then only call dequeue API. 

The flow should be

- Enqueue minimum two buffers 

- Wait for the callback

- Dequeue one buffer

- This buffer can be enqueued back after processing.. 

- Repeat steps 2 to 4.

Regards,

Brijesh  

Hi Brijesh,

Yes we are doing the same for example :

m_display->sendBuffer(0U, buffer);  //  Enqueue()
/*
* Wait for display callback
*/
m_display->waitForVsync();    // Wait for the callback
/*
* Dequeue the buffers
*/
val = m_display->receiveBuffer(0U, outputBuffer);   //  Dequeue()

outbuff[3]
count = 0

Enqueue(outbuff[0])
wait for vsync
if(count >= 2)
Dequeue()
count++

Enqueue(outbuff[1])
wait for vsync
if(count >= 2)
Dequeue()
count++

Enqueue(outbuff[2])
wait for vsync
if(count >= 2)
Dequeue(outbuff[2])
count++

Enqueue(outbuff[2])
wait for vsync
if(count >= 2)
Dequeue(outbuff[2])
count++

Enqueue(outbuff[2])
wait for vsync
if(count >= 2)
Dequeue(outbuff[2])
count++

and so on .........

Now outbuff[0] and outbuff[1] is not dequeued by Dequeue,  Only outbuff[2] is dequeued  .

So why 2 buffer its holding ( - Enqueue minimum two buffers  )  ??

Thanks

Kamalakkannan Sankarasubbaraj said:

So why 2 buffer its holding ( - Enqueue minimum two buffers  )  ??

But if you enqueue only one buffer, it will not give callback, because there is nothing to be dequeued, as this frame will be repeated. 

Regards,

Brijesh

Hi Brijesh ,

Ok this point I understood .

Now in our case even we gave 1st two buffer to Enqueue , after that why I am not getting back the 1st two buffer after call back.

ideally after callback we should get the previous buffer what we have queued , but those are never returned , as you can see in attached logs snapshot .  ?

hi,

After you get the callback, you can get back the first enqueued buffer. Now driver has only one buffer, so you need to enqueue one more to get back the second buffer on second callback.. 

Regards,

Brijesh