On 17 January 2018 at 10:38, Geert Uytterhoeven <geert+renesas@xxxxxxxxx> wrote:
> The current (empty) system sleep callbacks rely on the PM core to force
> a runtime resume to reinitialize the DMAC registers during system
> resume. Without a reinitialization, e.g. SCIF DMA will hang silently
> after a system resume on R-Car Gen3.
>
> Make this explicit by using pm_runtime_force_{suspend,resume}() as the
> system sleep callbacks instead. Use SET_LATE_SYSTEM_SLEEP_PM_OPS() as
> DMA engines must be initialized before all DMA slave devices.
>
> Suggested-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
> Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
Reviewed-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
Kind regards
Uffe
> ---
> This is a dependency for "[PATCH 1/2] PM / genpd: Stop/start devices
> without pm_runtime_force_suspend/resume()"
> (https://www.spinics.net/lists/kernel/msg2696802.html), so perhaps it
> makes most sense if Rafael takes it through the PM tree?
>
> Thanks!
> ---
> drivers/dma/sh/rcar-dmac.c | 24 +++++++-----------------
> 1 file changed, 7 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/dma/sh/rcar-dmac.c b/drivers/dma/sh/rcar-dmac.c
> index fb06b193ad252086..06e4e604eebb79f6 100644
> --- a/drivers/dma/sh/rcar-dmac.c
> +++ b/drivers/dma/sh/rcar-dmac.c
> @@ -1657,22 +1657,6 @@ static struct dma_chan *rcar_dmac_of_xlate(struct of_phandle_args *dma_spec,
> * Power management
> */
>
> -#ifdef CONFIG_PM_SLEEP
> -static int rcar_dmac_sleep_suspend(struct device *dev)
> -{
> - /*
> - * TODO: Wait for the current transfer to complete and stop the device.
> - */
> - return 0;
> -}
> -
> -static int rcar_dmac_sleep_resume(struct device *dev)
> -{
> - /* TODO: Resume transfers, if any. */
> - return 0;
> -}
> -#endif
> -
> #ifdef CONFIG_PM
> static int rcar_dmac_runtime_suspend(struct device *dev)
> {
> @@ -1688,7 +1672,13 @@ static int rcar_dmac_runtime_resume(struct device *dev)
> #endif
>
> static const struct dev_pm_ops rcar_dmac_pm = {
> - SET_SYSTEM_SLEEP_PM_OPS(rcar_dmac_sleep_suspend, rcar_dmac_sleep_resume)
> + /*
> + * TODO for system sleep/resume:
> + * - Wait for the current transfer to complete and stop the device,
> + * - Resume transfers, if any.
> + */
> + SET_LATE_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
> + pm_runtime_force_resume)
> SET_RUNTIME_PM_OPS(rcar_dmac_runtime_suspend, rcar_dmac_runtime_resume,
> NULL)
> };
> --
> 2.7.4
>
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