Re: [PATCH v1] dmaengine: tegra-apb: Error out if DMA_PREP_INTERRUPT flag is unset

[Jon Hunter]

On 29/05/2019 22:43, Dmitry Osipenko wrote:
> Apparently driver was never tested with DMA_PREP_INTERRUPT flag being
> unset since it completely disables interrupt handling instead of skipping
> the callbacks invocations, hence putting channel into unusable state.
> 
> The flag is always set by all of kernel drivers that use APB DMA, so let's
> error out in otherwise case for consistency. It won't be difficult to
> support that case properly if ever will be needed.
> 
> Signed-off-by: Dmitry Osipenko <digetx@xxxxxxxxx>
> ---
>  drivers/dma/tegra20-apb-dma.c | 12 ++++++++++--
>  1 file changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/dma/tegra20-apb-dma.c b/drivers/dma/tegra20-apb-dma.c
> index cf462b1abc0b..2c84a660ba36 100644
> --- a/drivers/dma/tegra20-apb-dma.c
> +++ b/drivers/dma/tegra20-apb-dma.c
> @@ -988,8 +988,12 @@ static struct dma_async_tx_descriptor *tegra_dma_prep_slave_sg(
>  		csr |= tdc->slave_id << TEGRA_APBDMA_CSR_REQ_SEL_SHIFT;
>  	}
>  
> -	if (flags & DMA_PREP_INTERRUPT)
> +	if (flags & DMA_PREP_INTERRUPT) {
>  		csr |= TEGRA_APBDMA_CSR_IE_EOC;
> +	} else {
> +		WARN_ON_ONCE(1);
> +		return NULL;
> +	}
>  
>  	apb_seq |= TEGRA_APBDMA_APBSEQ_WRAP_WORD_1;
>  
> @@ -1131,8 +1135,12 @@ static struct dma_async_tx_descriptor *tegra_dma_prep_dma_cyclic(
>  		csr |= tdc->slave_id << TEGRA_APBDMA_CSR_REQ_SEL_SHIFT;
>  	}
>  
> -	if (flags & DMA_PREP_INTERRUPT)
> +	if (flags & DMA_PREP_INTERRUPT) {
>  		csr |= TEGRA_APBDMA_CSR_IE_EOC;
> +	} else {
> +		WARN_ON_ONCE(1);
> +		return NULL;
> +	}
>  
>  	apb_seq |= TEGRA_APBDMA_APBSEQ_WRAP_WORD_1;

Looks good to me.

Acked-by: Jon Hunter <jonathanh@xxxxxxxxxx>

Cheers
Jon

-- 
nvpublic