Re: [PATCH 01/11] dmaengine: dw-axi-dmac: fix reading register hen runtime suspended

Jisheng Zhang
2023-04-15T10:13:18Z

On Wed, Apr 12, 2023 at 11:03:02PM +0530, Vinod Koul wrote:
> s/hen/when..? or something else
>
> On 14-03-23, 01:04, Jisheng Zhang wrote:
> > We should runtime resume the device before calling
> > axi_chan_is_hw_enable().
>
> why is that can you please explain..

If the device is suspended, I.E not resumed, accessing any
registers in axi_chan_is_hw_enable() will cause cpu abort.

I will add this info into commit log of v2.

>
> >
> > Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
> > ---
> > drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c | 15 +++++++++++----
> > 1 file changed, 11 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c b/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
> > index 7f3a60e28e38..23a10dbdecb7 100644
> > --- a/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
> > +++ b/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
> > @@ -462,13 +462,17 @@ static void dw_axi_dma_synchronize(struct dma_chan *dchan)
> >
> > static int dma_chan_alloc_chan_resources(struct dma_chan *dchan)
> > {
> > + int ret;
> > struct axi_dma_chan *chan = dchan_to_axi_dma_chan(dchan);
> >
> > + pm_runtime_get(chan->chip->dev);
> > +
> > /* ASSERT: channel is idle */
> > if (axi_chan_is_hw_enable(chan)) {
> > dev_err(chan2dev(chan), "%s is non-idle!\n",
> > axi_chan_name(chan));
> > - return -EBUSY;
> > + ret = -EBUSY;
> > + goto err_busy;
> > }
> >
> > /* LLI address must be aligned to a 64-byte boundary */
> > @@ -478,13 +482,16 @@ static int dma_chan_alloc_chan_resources(struct dma_chan *dchan)
> > 64, 0);
> > if (!chan->desc_pool) {
> > dev_err(chan2dev(chan), "No memory for descriptors\n");
> > - return -ENOMEM;
> > + ret = -ENOMEM;
> > + goto err_busy;
> > }
> > dev_vdbg(dchan2dev(dchan), "%s: allocating\n", axi_chan_name(chan));
> >
> > - pm_runtime_get(chan->chip->dev);
> > -
> > return 0;
> > +
> > +err_busy:
> > + pm_runtime_put(chan->chip->dev);
> > + return ret;
> > }
> >
> > static void dma_chan_free_chan_resources(struct dma_chan *dchan)
> > --
> > 2.39.2
>
> --
> ~Vinod