RE: [PATCH 3/4] dmaengine: sh: rz-dmac: Refactor runtime PM handling

[Biju Das]

Hi Tommaso,

> -----Original Message-----
> From: Tommaso Merciai <tommaso.merciai.xr@xxxxxxxxxxxxxx>
> Sent: 05 September 2025 15:44
> Subject: [PATCH 3/4] dmaengine: sh: rz-dmac: Refactor runtime PM handling
> 
> Refactor runtime PM handling to ensure correct power management and prevent resource leaks.  Invoke
> pm_runtime_get_sync() when allocating DMA channel resources and pm_runtime_put() when freeing them.
> Add pm_runtime_put() in
> rz_dmac_probe() to balance the usage count during device initialization, and remove the unnecessary
> pm_runtime_put() from rz_dmac_remove() to avoid PM inconsistencies.
> 
> Signed-off-by: Tommaso Merciai <tommaso.merciai.xr@xxxxxxxxxxxxxx>
> ---
>  drivers/dma/sh/rz-dmac.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/dma/sh/rz-dmac.c b/drivers/dma/sh/rz-dmac.c index 0bc11a6038383..4ab6076f5499e
> 100644
> --- a/drivers/dma/sh/rz-dmac.c
> +++ b/drivers/dma/sh/rz-dmac.c
> @@ -455,7 +455,7 @@ static int rz_dmac_alloc_chan_resources(struct dma_chan *chan)
>  	if (!channel->descs_allocated)
>  		return -ENOMEM;
> 
> -	return channel->descs_allocated;
> +	return pm_runtime_get_sync(chan->device->dev);

I would check for pm_runtime_resume_and_get(chan->device->dev) first
If successful, still will return channel->descs_allocated to comply with API documentation
rather than returning "runtime PM status"

@device_alloc_chan_resources: allocate resources and return the
number of allocated descriptors.

Cheers,
Biju