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SubjectRe: [PATCH v4 1/1] phy: fsl-imx8-mipi-dphy: Hook into runtime pm
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Hi Guido,

On Mon, 2021-02-22 at 19:38 +0100, Guido Günther wrote:
> This allows us to shut down the mipi power domain on the imx8. The
> alternative would be to drop the dphy from the mipi power domain in the
> SOCs device tree and only have the DSI host controller visible there but
> since the PD is mostly about the PHY that would defeat it's purpose.
>
> This allows to shut off the power domain hen blanking the LCD panel:

s/hen/when/

>
> pm_genpd_summary before:
>
> domain status slaves
> /device runtime status
> ----------------------------------------------------------------------
> mipi on
> /devices/platform/soc@0/soc@0:bus@30800000/30a00300.dphy unsupported
> /devices/platform/soc@0/soc@0:bus@30800000/30a00000.mipi_dsi suspended
>
> after:
>
> mipi off-0
> /devices/platform/soc@0/soc@0:bus@30800000/30a00300.dphy suspended
> /devices/platform/soc@0/soc@0:bus@30800000/30a00000.mipi_dsi suspended
>
> Signed-off-by: Guido Günther <agx@sigxcpu.org>
> ---
> drivers/phy/freescale/phy-fsl-imx8-mipi-dphy.c | 10 ++++++++++
> 1 file changed, 10 insertions(+)
>
> diff --git a/drivers/phy/freescale/phy-fsl-imx8-mipi-dphy.c b/drivers/phy/freescale/phy-fsl-imx8-mipi-dphy.c
> index a95572b397ca..5de175695834 100644
> --- a/drivers/phy/freescale/phy-fsl-imx8-mipi-dphy.c
> +++ b/drivers/phy/freescale/phy-fsl-imx8-mipi-dphy.c
> @@ -14,6 +14,7 @@
> #include <linux/of_platform.h>
> #include <linux/phy/phy.h>
> #include <linux/platform_device.h>
> +#include <linux/pm_runtime.h>
> #include <linux/regmap.h>
>
> /* DPHY registers */
> @@ -469,6 +470,8 @@ static int mixel_dphy_probe(struct platform_device *pdev)
>
> dev_set_drvdata(dev, priv);
>
> + pm_runtime_enable(dev);
> +

The runtime PM should be disabled if devm_phy_create()
or devm_of_phy_provider_register() fail.

Also, I'm just realizing that mixel_dphy_configure() accesses some PHY
registers, which likely needs the power domain on. However, the
phy-core doesn't manage the runtime PM for phy_configure(). It looks
that the NWL DSI bridge driver, which uses the PHY, enables the same
power domain prior to the PHY configuration. That's probably why
mixel_dphy_configure() gets power for accessing registers(if really
needed). So, perhaps, either make phy_configure() manage runtime PM or
get/put runtime PM in mixel_dphy_configure().

Regards,
Liu Ying

> phy = devm_phy_create(dev, np, &mixel_dphy_phy_ops);
> if (IS_ERR(phy)) {
> dev_err(dev, "Failed to create phy %ld\n", PTR_ERR(phy));
> @@ -481,8 +484,15 @@ static int mixel_dphy_probe(struct platform_device *pdev)
> return PTR_ERR_OR_ZERO(phy_provider);
> }
>
> +static int mixel_dphy_remove(struct platform_device *pdev)
> +{
> + pm_runtime_disable(&pdev->dev);
> + return 0;
> +}
> +
> static struct platform_driver mixel_dphy_driver = {
> .probe = mixel_dphy_probe,
> + .remove = mixel_dphy_remove,
> .driver = {
> .name = "mixel-mipi-dphy",
> .of_match_table = mixel_dphy_of_match,

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