linux-kernel - Re: [PATCH] dmaengine: ti: k3-udma: Avoid false error msg on chan teardown

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Date:   Sun, 20 Feb 2022 22:12:07 +0200
From:   Péter Ujfalusi <peter.ujfalusi@...il.com>
To:     Vignesh Raghavendra <vigneshr@...com>,
        Vinod Koul <vkoul@...nel.org>
Cc:     dmaengine@...r.kernel.org, linux-kernel@...r.kernel.org,
        Linux ARM Mailing List <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH] dmaengine: ti: k3-udma: Avoid false error msg on chan
 teardown

Hi Vignesh,

On 15/02/2022 06:41, Vignesh Raghavendra wrote:
> In cyclic mode, there is no additional descriptor pushed to collect
> outstanding data on channel teardown. Therefore no need to wait for this
> descriptor to come back.
> 
> Without this terminating aplay cmd outputs false error msg like:
> [  116.402800] ti-bcdma 485c0100.dma-controller: chan1 teardown timeout!

are you sure it is aplay? It is MEM_TO_DEV, we only use the flush
descriptor for DEV_TO_MEM. MEM_TO_DEV can 'disconnect' from the
peripheral to flush out the FIFO.

I have not seen this on am654, j721e. I can not recall seeing this on
the capture side either.

The cyclic TR should be able to drain the DEV_TO_MEM by itself and the
TR should terminate.


> Signed-off-by: Vignesh Raghavendra <vigneshr@...com>
> ---
>  drivers/dma/ti/k3-udma.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/dma/ti/k3-udma.c b/drivers/dma/ti/k3-udma.c
> index 9abb08d353ca0..c9a1b2f312603 100644
> --- a/drivers/dma/ti/k3-udma.c
> +++ b/drivers/dma/ti/k3-udma.c
> @@ -3924,7 +3924,7 @@ static void udma_synchronize(struct dma_chan *chan)
>  
>  	vchan_synchronize(&uc->vc);
>  
> -	if (uc->state == UDMA_CHAN_IS_TERMINATING) {
> +	if (uc->state == UDMA_CHAN_IS_TERMINATING && !uc->cyclic) {
>  		timeout = wait_for_completion_timeout(&uc->teardown_completed,
>  						      timeout);
>  		if (!timeout) {

-- 
Péter