On Friday, January 19, 2024 2:39 AM, Marek Vasut <marex@xxxxxxx> wrote:
> In case the LCDIF is enabled in DT but unused, the clock used by the
Nit: s/clock/clocks/
> LCDIF are not enabled. Those clock may even have a use count of 0 in
Ditto.
> case there are no other users of those clock. This can happen e.g. in
Ditto.
> case the LCDIF drives HDMI bridge which has no panel plugged into the
> HDMI connector.
>
> Do not attempt to disable clock in the suspend callback and re-enable
> clock in the resume callback unless the LCDIF is enabled and was in
> use before the system entered suspend, otherwise the driver might end
> up trying to disable clock which are already disabled with use count
Ditto.
With the nitpicks addressed:
Reviewed-by: Liu Ying <victor.liu@xxxxxxx>
Regards,
Liu Ying
> 0, and would trigger a warning from clock core about this condition.
>
> Note that the lcdif_rpm_suspend() and lcdif_rpm_resume() functions
> internally perform the clock disable and enable operations and act
> as runtime PM hooks too.
>
> Fixes: 9db35bb349a0 ("drm: lcdif: Add support for i.MX8MP LCDIF variant")
> Signed-off-by: Marek Vasut <marex@xxxxxxx>
> ---
> Cc: Daniel Vetter <daniel@xxxxxxxx>
> Cc: David Airlie <airlied@xxxxxxxxx>
> Cc: Fabio Estevam <festevam@xxxxxxxxx>
> Cc: Liu Ying <victor.liu@xxxxxxx>
> Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
> Cc: Maxime Ripard <mripard@xxxxxxxxxx>
> Cc: NXP Linux Team <linux-imx@xxxxxxx>
> Cc: Pengutronix Kernel Team <kernel@xxxxxxxxxxxxxx>
> Cc: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>
> Cc: Shawn Guo <shawnguo@xxxxxxxxxx>
> Cc: Stefan Agner <stefan@xxxxxxxx>
> Cc: Thomas Zimmermann <tzimmermann@xxxxxxx>
> Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
> Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
> ---
> drivers/gpu/drm/mxsfb/lcdif_drv.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/mxsfb/lcdif_drv.c
> b/drivers/gpu/drm/mxsfb/lcdif_drv.c
> index ea10bf81582e9..0f895b8a99d62 100644
> --- a/drivers/gpu/drm/mxsfb/lcdif_drv.c
> +++ b/drivers/gpu/drm/mxsfb/lcdif_drv.c
> @@ -343,6 +343,9 @@ static int __maybe_unused lcdif_suspend(struct
> device *dev)
> if (ret)
> return ret;
>
> + if (pm_runtime_suspended(dev))
> + return 0;
> +
> return lcdif_rpm_suspend(dev);
> }
>
> @@ -350,7 +353,8 @@ static int __maybe_unused lcdif_resume(struct
> device *dev)
> {
> struct drm_device *drm = dev_get_drvdata(dev);
>
> - lcdif_rpm_resume(dev);
> + if (!pm_runtime_suspended(dev))
> + lcdif_rpm_resume(dev);
>
> return drm_mode_config_helper_resume(drm);
> }
> --
> 2.43.0
