Messages in this thread | | | From | Anson Huang <> | Subject | RE: [PATCH] mailbox: imx: Support runtime PM | Date | Mon, 13 Apr 2020 13:13:28 +0000 |
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Hi, Marc
> Subject: Re: [PATCH] mailbox: imx: Support runtime PM > > On 4/13/20 2:25 PM, Anson Huang wrote: > > Some power hungry sub-systems like VPU has its own MUs which also use > > mailbox driver, current mailbox driver uses platform driver model and > > MU's power will be ON after driver probed and left ON there, it may > > cause the whole sub-system can NOT enter lower power mode, take VPU > > driver for example, it has runtime PM support, but due to its MU > > always ON, the VPU sub-system will be always ON and consume many power > > during kernel idle. > > > > To save power in kernel idle, mailbox driver needs to support runtime > > PM in order to power off MU when it is unused. However, the runtime > > suspend/resume can ONLY be implemented in mailbox's .shutdown/.startup > > callback, so its consumer needs to call > > mbox_request_channel()/mbox_free_channel() in consumer driver's > > runtime PM callback, then the MU's power will be ON/OFF along with > > consumer's runtime PM status. > > > > Signed-off-by: Anson Huang <Anson.Huang@nxp.com> > > --- > > drivers/mailbox/imx-mailbox.c | 27 ++++++++++++++++++++++++++- > > 1 file changed, 26 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/mailbox/imx-mailbox.c > > b/drivers/mailbox/imx-mailbox.c index 7906624..97bf0ac 100644 > > --- a/drivers/mailbox/imx-mailbox.c > > +++ b/drivers/mailbox/imx-mailbox.c > > @@ -12,6 +12,7 @@ > > #include <linux/mailbox_controller.h> #include <linux/module.h> > > #include <linux/of_device.h> > > +#include <linux/pm_runtime.h> > > #include <linux/slab.h> > > > > #define IMX_MU_xSR_GIPn(x) BIT(28 + (3 - (x))) > > @@ -287,6 +288,7 @@ static int imx_mu_startup(struct mbox_chan *chan) > > struct imx_mu_con_priv *cp = chan->con_priv; > > int ret; > > > > + pm_runtime_get_sync(priv->dev); > > if (cp->type == IMX_MU_TYPE_TXDB) { > > /* Tx doorbell don't have ACK support */ > > tasklet_init(&cp->txdb_tasklet, imx_mu_txdb_tasklet, @@ -323,6 > > +325,7 @@ static void imx_mu_shutdown(struct mbox_chan *chan) > > > > if (cp->type == IMX_MU_TYPE_TXDB) { > > tasklet_kill(&cp->txdb_tasklet); > > + pm_runtime_put_sync(priv->dev); > > return; > > } > > > > @@ -341,6 +344,7 @@ static void imx_mu_shutdown(struct mbox_chan > *chan) > > } > > > > free_irq(priv->irq, chan); > > + pm_runtime_put_sync(priv->dev); > > } > > > > static const struct mbox_chan_ops imx_mu_ops = { @@ -508,7 +512,27 > @@ > > static int imx_mu_probe(struct platform_device *pdev) > > > > platform_set_drvdata(pdev, priv); > > > > - return devm_mbox_controller_register(dev, &priv->mbox); > > + ret = devm_mbox_controller_register(dev, &priv->mbox); > > + if (ret) > > + return ret; > > + > > + pm_runtime_enable(dev); > > + > > First registering at the system and then setting up the power management > looks racy. Don't know if this is serialized by some other means.
Don't have other means, just refer to drivers/mailbox/omap-mailbox.c, it has same sequence, NOT sure if there is special requirement about this sequence.
Thanks, Anson
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