linux-kernel - Re: [PATCH] media: coda: Keep metas sync with hardware fifo

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Message-ID: <4247f8c1-496b-4026-a328-284a495b88f3@collabora.com>
Date:   Fri, 12 Nov 2021 09:36:47 +0100
From:   Benjamin Gaignard <benjamin.gaignard@...labora.com>
To:     Philipp Zabel <p.zabel@...gutronix.de>, mchehab@...nel.org
Cc:     linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        kernel@...labora.com
Subject: Re: [PATCH] media: coda: Keep metas sync with hardware fifo


Le 11/11/2021 à 18:03, Philipp Zabel a écrit :
> Hi Benjamin,
>
> On Mon, 2021-11-08 at 15:24 +0100, Benjamin Gaignard wrote:
>> After updating the output fifo position be sure that metas are also
>> synchronised with this position.
>>
>> Signed-off-by: Benjamin Gaignard <benjamin.gaignard@...labora.com>
>> ---
>>   drivers/media/platform/coda/coda-bit.c | 6 ++++++
>>   1 file changed, 6 insertions(+)
>>
>> diff --git a/drivers/media/platform/coda/coda-bit.c b/drivers/media/platform/coda/coda-bit.c
>> index c484c008ab02..28c56286b0de 100644
>> --- a/drivers/media/platform/coda/coda-bit.c
>> +++ b/drivers/media/platform/coda/coda-bit.c
>> @@ -2315,6 +2315,12 @@ static void coda_finish_decode(struct coda_ctx *ctx)
>>   	/* Update kfifo out pointer from coda bitstream read pointer */
>>   	coda_kfifo_sync_from_device(ctx);
>>
>> +	/*
>> +	 * After updating the read pointer, we need to check if
>> +	 * any metas are consumed and should be released.
>> +	 */
>> +	coda_decoder_drop_used_metas(ctx);
>> +
> This doesn't look right. If you drop all metas seen by the decoder right
> away, they can't be copied into the decoded picture's meta slot later in
> this function. I'd expect you run into the "empty timestamp list!"
> errors if you do this.

Hi Philipp,

I don't run into the "empty timestamp list!" errors.
The only case I have seen metas been dropped here it is when
an invalid/incomplete frame has been send into the decoder.
When that happens I don't see any interrupt or error message but
the erroneous frame stay in the list.
If that occur 4 times (I'm using CODA 960) then the decoder hang.
Dropping the metas at this moment solve this problem.

Maybe you can guide me to a better solution ?

Regards,
Benjamin

>
> regards
> Philipp