Hi,
On 05/05/2025 17:45, Vitor Soares wrote:
On Tue, 2025-04-29 at 09:32 +0300, Tomi Valkeinen wrote:
Hi,
On 28/04/2025 12:40, Vitor Soares wrote:
From: Vitor Soares <vitor.soa...@toradex.com>
The deprecated UNIVERSAL_DEV_PM_OPS() macro uses the provided callbacks
for both runtime PM and system sleep. This causes the DSI clocks to be
disabled twice: once during runtime suspend and again during system
suspend, resulting in a WARN message from the clock framework when
attempting to disable already-disabled clocks.
[ 84.384540] clk:231:5 already disabled
[ 84.388314] WARNING: CPU: 2 PID: 531 at /drivers/clk/clk.c:1181
clk_core_disable+0xa4/0xac
...
[ 84.579183] Call trace:
[ 84.581624] clk_core_disable+0xa4/0xac
[ 84.585457] clk_disable+0x30/0x4c
[ 84.588857] cdns_dsi_suspend+0x20/0x58 [cdns_dsi]
[ 84.593651] pm_generic_suspend+0x2c/0x44
[ 84.597661] ti_sci_pd_suspend+0xbc/0x15c
[ 84.601670] dpm_run_callback+0x8c/0x14c
[ 84.605588] __device_suspend+0x1a0/0x56c
[ 84.609594] dpm_suspend+0x17c/0x21c
[ 84.613165] dpm_suspend_start+0xa0/0xa8
[ 84.617083] suspend_devices_and_enter+0x12c/0x634
[ 84.621872] pm_suspend+0x1fc/0x368
To address this issue, replace UNIVERSAL_DEV_PM_OPS() with
DEFINE_RUNTIME_DEV_PM_OPS(), which avoids redundant suspend/resume calls
by checking if the device is already runtime suspended.
Cc: <sta...@vger.kernel.org> # 6.1.x
Fixes: e19233955d9e ("drm/bridge: Add Cadence DSI driver")
Signed-off-by: Vitor Soares <vitor.soa...@toradex.com>
---
drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c
b/drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c
index b022dd6e6b6e..62179e55e032 100644
--- a/drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c
+++ b/drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c
@@ -1258,7 +1258,7 @@ static const struct mipi_dsi_host_ops cdns_dsi_ops = {
.transfer = cdns_dsi_transfer,
};
-static int __maybe_unused cdns_dsi_resume(struct device *dev)
+static int cdns_dsi_resume(struct device *dev)
{
struct cdns_dsi *dsi = dev_get_drvdata(dev);
@@ -1269,7 +1269,7 @@ static int __maybe_unused cdns_dsi_resume(struct
device *dev)
return 0;
}
-static int __maybe_unused cdns_dsi_suspend(struct device *dev)
+static int cdns_dsi_suspend(struct device *dev)
{
struct cdns_dsi *dsi = dev_get_drvdata(dev);
@@ -1279,8 +1279,8 @@ static int __maybe_unused cdns_dsi_suspend(struct
device *dev)
return 0;
}
-static UNIVERSAL_DEV_PM_OPS(cdns_dsi_pm_ops, cdns_dsi_suspend,
cdns_dsi_resume,
- NULL);
+static DEFINE_RUNTIME_DEV_PM_OPS(cdns_dsi_pm_ops, cdns_dsi_suspend,
+ cdns_dsi_resume, NULL);
I'm not sure if this, or the UNIVERSAL_DEV_PM_OPS, is right here. When
the system is suspended, the bridge drivers will get a call to the
*_disable() hook, which then disables the device. If the bridge driver
would additionally do something in its system suspend hook, it would
conflict with normal disable path.
I think bridges/panels should only deal with runtime PM.
Tomi
In the proposed change, we make use of pm_runtime_force_suspend() during
system-wide suspend. If the device is already suspended, this call is a
no-op and disables runtime PM to prevent spurious wakeups during the
suspend period. Otherwise, it triggers the device’s runtime_suspend()
callback.
I briefly reviewed other bridge drivers, and those that implement runtime
PM appear to follow a similar approach, relying solely on runtime PM
callbacks and using pm_runtime_force_suspend()/resume() to handle
system-wide transitions.
Yes, I see such a solution in some of the bridge and panel drivers. I'm
probably missing something here, as I don't think it's correct.
Why do we need to set the system suspend/resume hooks? What is the
scenario where those will be called, and the
pm_runtime_force_suspend()/resume() do something that's not already done
via the normal DRM pipeline enable/disable?
Tomi
