On Wed, Jun 29, 2016 at 05:08:39PM +0100, Jon Hunter wrote:
> Commit 71f7e6cc5500 ('dmaengine: tegra20-apb-dma: Only calculate residue
> if txstate exists') changed the tegra_dma_tx_status() function to only
> calculate the residue if there is a valid 'txstate' pointer for storing
> the residue. Although this makes sense, this changed the behaviour of
> the function tegra_dma_tx_status() such that if the pointer 'txstate' is
> not valid, then we will return whatever state is returned by
> dma_cookie_status() and no longer return the state by looking up the DMA
> descriptor and returning it's state.
> 
> Please note that dma_cookie_status() will either return DMA_COMPLETE or
> DMA_IN_PROGRESS. However, if dma_cookie_status() returns DMA_IN_PROGRESS
> the actual status could be DMA_ERROR which will only be seen from
> checking the descriptor status. Therefore, even if 'txstate' is not
> valid, still check to see if there is a valid descriptor for the cookie
> in question and if so return the descriptor state. Finally, ensure the
> residue is still not calculated if the 'txstate' is not valid.
> 
> Signed-off-by: Jon Hunter <jonathanh-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
> ---
>  drivers/dma/tegra20-apb-dma.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)

Acked-by: Thierry Reding <treding-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>