linux-kernel - Re: [PATCH 4/5] drm/msm/dp: Try looking for link-frequencies into the port@0's endpoint first

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Date: Mon, 29 Jan 2024 17:08:29 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Abel Vesa <abel.vesa@...aro.org>
Cc: Rob Clark <robdclark@...il.com>, Abhinav Kumar <quic_abhinavk@...cinc.com>, 
	Sean Paul <sean@...rly.run>, Marijn Suijten <marijn.suijten@...ainline.org>, 
	David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>, 
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, Maxime Ripard <mripard@...nel.org>, 
	Thomas Zimmermann <tzimmermann@...e.de>, Rob Herring <robh+dt@...nel.org>, 
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>, Conor Dooley <conor+dt@...nel.org>, 
	Neil Armstrong <neil.armstrong@...aro.org>, linux-arm-msm@...r.kernel.org, 
	dri-devel@...ts.freedesktop.org, freedreno@...ts.freedesktop.org, 
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/5] drm/msm/dp: Try looking for link-frequencies into the
 port@0's endpoint first

On Mon, 29 Jan 2024 at 15:19, Abel Vesa <abel.vesa@...aro.org> wrote:
>
> From: Abhinav Kumar <quic_abhinavk@...cinc.com>
>
> On platforms where the endpoint used is on port@0, looking for port@1
> instead results in just ignoring the max link-frequencies altogether.
> Look at port@0 first, then, if not found, look for port@1.

NAK. Platforms do not "use port@0". It is for the connection between
DPU and DP, while the link-frequencies property is for the link
between DP controller and the actual display.

>
> Signed-off-by: Abhinav Kumar <quic_abhinavk@...cinc.com>
> Signed-off-by: Abel Vesa <abel.vesa@...aro.org>
> ---
>  drivers/gpu/drm/msm/dp/dp_parser.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/msm/dp/dp_parser.c b/drivers/gpu/drm/msm/dp/dp_parser.c
> index 7032dcc8842b..eec5b8b83f4b 100644
> --- a/drivers/gpu/drm/msm/dp/dp_parser.c
> +++ b/drivers/gpu/drm/msm/dp/dp_parser.c
> @@ -97,7 +97,11 @@ static u32 dp_parser_link_frequencies(struct device_node *of_node)
>         u64 frequency = 0;
>         int cnt;
>
> -       endpoint = of_graph_get_endpoint_by_regs(of_node, 1, 0); /* port@1 */
> +       endpoint = of_graph_get_endpoint_by_regs(of_node, 0, 0); /* port@0 */
> +
> +       if (!endpoint)
> +               endpoint = of_graph_get_endpoint_by_regs(of_node, 1, 0); /* port@1 */
> +
>         if (!endpoint)
>                 return 0;
>
>
> --
> 2.34.1
>


-- 
With best wishes
Dmitry