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

From: Marek Vasut <marex@denx.de>
To: Jagan Teki <jagan@amarulasolutions.com>
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: Mon, 27 Feb 2023 20:08:45 +0100	[thread overview]
Message-ID: <7b59aaf9-1f72-fd9f-29ac-1857ec3f91f3@denx.de> (raw)
In-Reply-To: <CAMty3ZA6_pKiOK6gWq4iQFtKsoxfUgnSFBqkgDBzEp1DcBEt3A@mail.gmail.com>

On 2/27/23 20:01, Jagan Teki wrote:
> 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.

In 14/18 patch, the same should be added to generic_dsim_register_host() 
, which is called from the driver .probe() callback, but that is OK.

That's ^ is the iMX part.

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