Re: [PATCH v13 04/18] drm: exynos: dsi: Switch to DSI panel or bridge find helper

From: Jagan Teki <jagan@amarulasolutions.com>
To: Marek Vasut <marex@denx.de>
Cc: Andrzej Hajda <andrzej.hajda@intel.com>,
	Inki Dae <inki.dae@samsung.com>,
	 Marek Szyprowski <m.szyprowski@samsung.com>,
	Seung-Woo Kim <sw0312.kim@samsung.com>,
	 Kyungmin Park <kyungmin.park@samsung.com>,
	Frieder Schrempf <frieder.schrempf@kontron.de>,
	 Tim Harvey <tharvey@gateworks.com>,
	Adam Ford <aford173@gmail.com>,
	 Laurent Pinchart <Laurent.pinchart@ideasonboard.com>,
	Maxime Ripard <maxime@cerno.tech>,
	 Matteo Lisi <matteo.lisi@engicam.com>,
	dri-devel@lists.freedesktop.org,
	 linux-samsung-soc@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	 NXP Linux Team <linux-imx@nxp.com>,
	linux-amarula <linux-amarula@amarulasolutions.com>
Subject: Re: [PATCH v13 04/18] drm: exynos: dsi: Switch to DSI panel or bridge find helper
Date: Tue, 28 Feb 2023 00:31:23 +0530	[thread overview]
Message-ID: <CAMty3ZA6_pKiOK6gWq4iQFtKsoxfUgnSFBqkgDBzEp1DcBEt3A@mail.gmail.com> (raw)
In-Reply-To: <3c2f91d3-0406-7730-d4e4-c94868f23c91@denx.de>

On Tue, Feb 28, 2023 at 12:25 AM Marek Vasut <marex@denx.de> wrote:
>
> On 2/27/23 12:39, Jagan Teki wrote:
> > drm_of_dsi_find_panel_or_bridge is capable of looking up the
> > downstream DSI bridge and panel and trying to add a panel bridge
> > if the panel is found.
> >
> > Replace explicit finding calls with drm_of_dsi_find_panel_or_bridge
> > followed with drmm_panel_bridge_add.
> >
> > Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
> > ---
> > Changes for v13, v12, v11:
> > - none
> > Changes for v10:
> > - new patch
> >
> >   drivers/gpu/drm/exynos/exynos_drm_dsi.c | 25 +++++++++++++------------
> >   1 file changed, 13 insertions(+), 12 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/exynos/exynos_drm_dsi.c b/drivers/gpu/drm/exynos/exynos_drm_dsi.c
> > index df15501b1075..12a6dd987e8f 100644
> > --- a/drivers/gpu/drm/exynos/exynos_drm_dsi.c
> > +++ b/drivers/gpu/drm/exynos/exynos_drm_dsi.c
> > @@ -25,6 +25,7 @@
> >   #include <drm/drm_atomic_helper.h>
> >   #include <drm/drm_bridge.h>
> >   #include <drm/drm_mipi_dsi.h>
> > +#include <drm/drm_of.h>
> >   #include <drm/drm_panel.h>
> >   #include <drm/drm_print.h>
> >   #include <drm/drm_probe_helper.h>
> > @@ -1470,24 +1471,26 @@ static int exynos_dsi_host_attach(struct mipi_dsi_host *host,
> >       struct device *dev = dsi->dev;
> >       struct drm_encoder *encoder = &dsi->encoder;
> >       struct drm_device *drm = encoder->dev;
> > +     struct drm_bridge *bridge;
> >       struct drm_panel *panel;
> >       int ret;
> >
> > -     panel = of_drm_find_panel(device->dev.of_node);
> > -     if (!IS_ERR(panel)) {
> > -             dsi->out_bridge = devm_drm_panel_bridge_add(dev, panel);
> > -     } else {
> > -             dsi->out_bridge = of_drm_find_bridge(device->dev.of_node);
> > -             if (!dsi->out_bridge)
> > -                     dsi->out_bridge = ERR_PTR(-EINVAL);
> > -     }
>
> As far as I understand this from my conversation with Maxime (please put
> him on CC of V15), the change here should instead perform the panel look
> up NOT in exynos_dsi_host_attach() , but in exynos_dsi_bind() , i.e. in
> the component_ops .bind callback . Here is an example of correct
> implementation:
>
> https://cgit.freedesktop.org/drm-misc/tree/drivers/gpu/drm/vc4/vc4_dsi.c#n1805

But, we don't have component_ops.bind for imx8m case, so where do we
want to place the panel hook?

Exynos drm drivers are component-based but, imx8mm is not.

Jagan.

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