Patch "drm/lcdif: Do not disable clocks on already suspended hardware" has been added to the 6.8-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    drm/lcdif: Do not disable clocks on already suspended hardware

to the 6.8-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     drm-lcdif-do-not-disable-clocks-on-already-suspended.patch
and it can be found in the queue-6.8 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit d98580424fb182f2c95d19be352917df7fc3b67b
Author: Marek Vasut <marex@xxxxxxx>
Date:   Mon Feb 26 09:26:27 2024 +0100

    drm/lcdif: Do not disable clocks on already suspended hardware
    
    [ Upstream commit 172695f145fb4798ab605e8a73f6e87711930124 ]
    
    In case the LCDIF is enabled in DT but unused, the clocks used by the
    LCDIF are not enabled. Those clocks may even have a use count of 0 in
    case there are no other users of those clocks. This can happen e.g. in
    case the LCDIF drives HDMI bridge which has no panel plugged into the
    HDMI connector.
    
    Do not attempt to disable clocks in the suspend callback and re-enable
    clocks 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 clocks which are already disabled with use count
    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 clocks disable and enable operations and act
    as runtime PM hooks too.
    
    Reviewed-by: Liu Ying <victor.liu@xxxxxxx>
    Fixes: 9db35bb349a0 ("drm: lcdif: Add support for i.MX8MP LCDIF variant")
    Signed-off-by: Marek Vasut <marex@xxxxxxx>
    Link: https://patchwork.freedesktop.org/patch/msgid/20240226082644.32603-1-marex@xxxxxxx
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/gpu/drm/mxsfb/lcdif_drv.c b/drivers/gpu/drm/mxsfb/lcdif_drv.c
index 18de2f17e2491..6494e82707569 100644
--- a/drivers/gpu/drm/mxsfb/lcdif_drv.c
+++ b/drivers/gpu/drm/mxsfb/lcdif_drv.c
@@ -340,6 +340,9 @@ 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);
 }
 
@@ -347,7 +350,8 @@ 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);
 }