linux-kernel - Re: [PATCH AUTOSEL 6.6 04/10] drm: display: Set fwnode for aux bus devices

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Message-ID: <CAGETcx9RpUz0hR-X+rO6yKRxOmrMLveU7EMSACF49kMTMqdaRg@mail.gmail.com>
Date: Thu, 5 Dec 2024 16:05:35 -0800
From: Saravana Kannan <saravanak@...gle.com>
To: Sasha Levin <sashal@...nel.org>
Cc: linux-kernel@...r.kernel.org, stable@...r.kernel.org, 
	Nícolas F . R . A . Prado <nfraprado@...labora.com>, 
	Dmitry Baryshkov <dmitry.baryshkov@...aro.org>, Thierry Reding <treding@...dia.com>, 
	AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>, 
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>, maarten.lankhorst@...ux.intel.com, 
	mripard@...nel.org, tzimmermann@...e.de, airlied@...il.com, simona@...ll.ch, 
	matthias.bgg@...il.com, elder@...nel.org, sumit.garg@...aro.org, 
	ricardo@...liere.net, dri-devel@...ts.freedesktop.org, 
	linux-arm-kernel@...ts.infradead.org, linux-mediatek@...ts.infradead.org
Subject: Re: [PATCH AUTOSEL 6.6 04/10] drm: display: Set fwnode for aux bus devices

On Wed, Dec 4, 2024 at 3:29 PM Sasha Levin <sashal@...nel.org> wrote:
>
> From: Saravana Kannan <saravanak@...gle.com>
>
> [ Upstream commit fe2e59aa5d7077c5c564d55b7e2997e83710c314 ]
>
> fwnode needs to be set for a device for fw_devlink to be able to
> track/enforce its dependencies correctly. Without this, you'll see error
> messages like this when the supplier has probed and tries to make sure
> all its fwnode consumers are linked to it using device links:
>
> mediatek-drm-dp 1c500000.edp-tx: Failed to create device link (0x180) with backlight-lcd0
>
> Reported-by: Nícolas F. R. A. Prado <nfraprado@...labora.com>
> Closes: https://lore.kernel.org/all/7b995947-4540-4b17-872e-e107adca4598@notapiano/
> Tested-by: Nícolas F. R. A. Prado <nfraprado@...labora.com>
> Signed-off-by: Saravana Kannan <saravanak@...gle.com>
> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
> Reviewed-by: Thierry Reding <treding@...dia.com>
> Tested-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
> Link: https://lore.kernel.org/r/20241024061347.1771063-2-saravanak@google.com
> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> Signed-off-by: Sasha Levin <sashal@...nel.org>

As mentioned in the original cover letter:

PSA: Do not pull any of these patches into stable kernels. fw_devlink
had a lot of changes that landed in the last year. It's hard to ensure
cherry-picks have picked up all the dependencies correctly. If any of
these really need to get cherry-picked into stable kernels, cc me and
wait for my explicit Ack.

Is there a pressing need for this in 4.19?

-Saravana

> ---
>  drivers/gpu/drm/display/drm_dp_aux_bus.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/display/drm_dp_aux_bus.c b/drivers/gpu/drm/display/drm_dp_aux_bus.c
> index 8a165be1a8214..d15c0f184983b 100644
> --- a/drivers/gpu/drm/display/drm_dp_aux_bus.c
> +++ b/drivers/gpu/drm/display/drm_dp_aux_bus.c
> @@ -292,7 +292,7 @@ int of_dp_aux_populate_bus(struct drm_dp_aux *aux,
>         aux_ep->dev.parent = aux->dev;
>         aux_ep->dev.bus = &dp_aux_bus_type;
>         aux_ep->dev.type = &dp_aux_device_type_type;
> -       aux_ep->dev.of_node = of_node_get(np);
> +       device_set_node(&aux_ep->dev, of_fwnode_handle(of_node_get(np)));
>         dev_set_name(&aux_ep->dev, "aux-%s", dev_name(aux->dev));
>
>         ret = device_register(&aux_ep->dev);
> --
> 2.43.0
>