linux-kernel - Re: [PATCH 1/5] drm/panel: Add helper for reading DT rotation

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Message-ID: <20190612212054.GB13155@ravnborg.org>
Date:   Wed, 12 Jun 2019 23:20:54 +0200
From:   Sam Ravnborg <sam@...nborg.org>
To:     Derek Basehore <dbasehore@...omium.org>
Cc:     linux-kernel@...r.kernel.org,
        Thierry Reding <thierry.reding@...il.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <maxime.ripard@...tlin.com>,
        Sean Paul <sean@...rly.run>,
        Jani Nikula <jani.nikula@...ux.intel.com>,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@...el.com>,
        CK Hu <ck.hu@...iatek.com>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Matthias Brugger <matthias.bgg@...il.com>,
        dri-devel@...ts.freedesktop.org, devicetree@...r.kernel.org,
        intel-gfx@...ts.freedesktop.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org
Subject: Re: [PATCH 1/5] drm/panel: Add helper for reading DT rotation

Hi Derek.

On Mon, Jun 10, 2019 at 09:03:46PM -0700, Derek Basehore wrote:
> This adds a helper function for reading the rotation (panel
> orientation) from the device tree.
> 
> Signed-off-by: Derek Basehore <dbasehore@...omium.org>
> ---
>  drivers/gpu/drm/drm_panel.c | 41 +++++++++++++++++++++++++++++++++++++
>  include/drm/drm_panel.h     |  7 +++++++
>  2 files changed, 48 insertions(+)
> 
> diff --git a/drivers/gpu/drm/drm_panel.c b/drivers/gpu/drm/drm_panel.c
> index dbd5b873e8f2..3b689ce4a51a 100644
> --- a/drivers/gpu/drm/drm_panel.c
> +++ b/drivers/gpu/drm/drm_panel.c
> @@ -172,6 +172,47 @@ struct drm_panel *of_drm_find_panel(const struct device_node *np)
>  	return ERR_PTR(-EPROBE_DEFER);
>  }
>  EXPORT_SYMBOL(of_drm_find_panel);
> +
> +/**
> + * of_drm_get_panel_orientation - look up the rotation of the panel using a
> + * device tree node
> + * @np: device tree node of the panel
> + * @orientation: orientation enum to be filled in
> + *
> + * Looks up the rotation of a panel in the device tree. The rotation in the
> + * device tree is counter clockwise.
> + *
> + * Return: 0 when a valid rotation value (0, 90, 180, or 270) is read or the
> + * rotation property doesn't exist. -EERROR otherwise.
> + */
> +int of_drm_get_panel_orientation(const struct device_node *np, int *orientation)
> +{
> +	int rotation, ret;
> +
> +	ret = of_property_read_u32(np, "rotation", &rotation);

I just noticed that everywhere this code talks about orientation,
but the property that it reads are rotation.
To my best understanding these are not the same.

	Sam