Re: [PATCH] ARM: imx: drop devlinks to reset-controller node

Hi Philipp,

On Tue, Sep 21, 2021 at 8:05 AM Philipp Zabel [off-list ref] wrote:

Hi Saravana,

On Tue, 2021-09-21 at 07:45 -0700, Saravana Kannan wrote:

quoted

On Tue, Sep 21, 2021 at 5:50 AM Philipp Zabel [off-list ref] wrote:

quoted

Starting with commit 6b2117ad65f1 ("of: property: fw_devlink: Add
support for "resets" and "pwms""), the imx-drm driver fails to load
due to forever dormant devlinks to the reset-controller node. This
node is never associated with a struct device.

Drop those links, the reset controller is always available.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
---
 arch/arm/mach-imx/src.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/arch/arm/mach-imx/src.c b/arch/arm/mach-imx/src.c
index 95fd1fbb0826..6924ac19a762 100644
--- a/arch/arm/mach-imx/src.c
+++ b/arch/arm/mach-imx/src.c

@@ -178,9 +178,17 @@ void __init imx_src_init(void)
        WARN_ON(!src_base);

        imx_reset_controller.of_node = np;
-       if (IS_ENABLED(CONFIG_RESET_CONTROLLER))
+       if (IS_ENABLED(CONFIG_RESET_CONTROLLER)) {
                reset_controller_register(&imx_reset_controller);

+               /*
+                * The reset-controller node is never associated with a struct
+                * device, which trips up fw_devlink=on. As a workaround, drop
+                * all devlinks to/from this node.
+                */
+               fw_devlink_purge_absent_suppliers(&np->fwnode);
+       }
+

Hey Philipp,

Can you point me to the .dts file that corresponds to this platform? I
want to take a closer look.

Thank you, the relevant file is arch/arm/boot/dts/imx6qdl.dtsi, device
nodes labeled as &src and &ipu1. This is for example included by
arch/arm/boot/dts/imx6q-nitrogen6x.dts. There's a second &ipu2 added in
arch/arm/boot/dts/imx6qd.dtsi as well.

I took a closer look at the DT. Is there really no struct device for
this node? Based on the DT, it looks like a device would automatically
get created for this node. So it looks like it's more of an issue with
the device not being probed by a real driver? Why can't you convert
the reset controller driver to a proper platform driver instead of
this patch? I think that's the right fix.

-Saravana

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