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From: Joel Selvaraj <jo@jsfamily.in>
To: Joel Selvaraj <jo@jsfamily.in>, Douglas Anderson <dianders@chromium.org>,
	"dri-devel@lists.freedesktop.org" <dri-devel@lists.freedesktop.org>, Maxime
 Ripard <mripard@kernel.org>
CC: Linus Walleij <linus.walleij@linaro.org>, Chris Morgan
	<macromorgan@hotmail.com>, Yuran Pereira <yuran.pereira@hotmail.com>, Neil
 Armstrong <neil.armstrong@linaro.org>, Sumit Semwal
	<sumit.semwal@linaro.org>, Benni Steini <bennisteinir@gmail.com>, Marijn
 Suijten <marijn.suijten@somainline.org>, Daniel Vetter <daniel@ffwll.ch>,
	David Airlie <airlied@gmail.com>, Jessica Zhang <quic_jesszhan@quicinc.com>,
	Maarten Lankhorst <maarten.lankhorst@linux.intel.com>, Sam Ravnborg
	<sam@ravnborg.org>, Thomas Zimmermann <tzimmermann@suse.de>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [RFT PATCH v2 19/48] drm/panel: novatek-nt36672a: Don't call
 unprepare+disable at shutdown/remove
Thread-Topic: [RFT PATCH v2 19/48] drm/panel: novatek-nt36672a: Don't call
 unprepare+disable at shutdown/remove
Thread-Index: AQHanaIO/k7pPw0oNk2UsoHQMRYmRbGHwevFgAADXkw=
Date: Sun, 5 May 2024 00:10:26 +0000
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Sorry for the long lines. Had to use a different email client and ended mes=
sing it up.

Regards
Joel Selvaraj

________________________________________
From: Joel Selvaraj <jo@jsfamily.in>
Sent: 05 May 2024 05:28
To: Douglas Anderson; dri-devel@lists.freedesktop.org; Maxime Ripard
Cc: Linus Walleij; Chris Morgan; Yuran Pereira; Neil Armstrong; Sumit Semwa=
l; Benni Steini; Marijn Suijten; Daniel Vetter; David Airlie; Jessica Zhang=
; Maarten Lankhorst; Sam Ravnborg; Thomas Zimmermann; linux-kernel@vger.ker=
nel.org
Subject: Re: [RFT PATCH v2 19/48] drm/panel: novatek-nt36672a: Don't call u=
nprepare+disable at shutdown/remove

Hi Douglas Anderson,

Poco F1 is one of the main user for this panel. I tested the patch in my Po=
co F1 running postmarketOS. It works fine. Thank you. The panel itself requ=
ires other extra fixes to work properly which I intend to upstream in the u=
pcoming weeks. But your patch doesn't break anything and works as expected.=
 So.

Tested-by: Joel Selvaraj <jo@jsfamily.in>

Regards
Joel Selvaraj

________________________________________
From: Douglas Anderson <dianders@chromium.org>
Sent: 04 May 2024 03:03
To: dri-devel@lists.freedesktop.org; Maxime Ripard
Cc: Linus Walleij; Chris Morgan; Yuran Pereira; Neil Armstrong; Douglas And=
erson; Sumit Semwal; Benni Steini; Joel Selvaraj; Marijn Suijten; Daniel Ve=
tter; David Airlie; Jessica Zhang; Maarten Lankhorst; Sam Ravnborg; Thomas =
Zimmermann; linux-kernel@vger.kernel.org
Subject: [RFT PATCH v2 19/48] drm/panel: novatek-nt36672a: Don't call unpre=
pare+disable at shutdown/remove

It's the responsibility of a correctly written DRM modeset driver to
call drm_atomic_helper_shutdown() at shutdown time and that should be
disabling / unpreparing the panel if needed. Panel drivers shouldn't
be calling these functions themselves.

A recent effort was made to fix as many DRM modeset drivers as
possible [1] [2] [3] and most drivers are fixed now.

A grep through mainline for compatible strings used by this driver
indicates that it is used by Qualcomm boards. The Qualcomm driver
appears to be correctly calling drm_atomic_helper_shutdown() so we can
remove the calls.

[1] https://lore.kernel.org/r/20230901234015.566018-1-dianders@chromium.org
[2] https://lore.kernel.org/r/20230901234202.566951-1-dianders@chromium.org
[3] https://lore.kernel.org/r/20230921192749.1542462-1-dianders@chromium.or=
g

Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Benni Steini <bennisteinir@gmail.com>
Cc: Joel Selvaraj <jo@jsfamily.in>
Cc: Marijn Suijten <marijn.suijten@somainline.org>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
---

Changes in v2:
- Only handle 1 panel per patch.
- Split removal of prepared/enabled from handling of remove/shutdown.

 drivers/gpu/drm/panel/panel-novatek-nt36672a.c | 17 -----------------
 1 file changed, 17 deletions(-)

diff --git a/drivers/gpu/drm/panel/panel-novatek-nt36672a.c b/drivers/gpu/d=
rm/panel/panel-novatek-nt36672a.c
index 35aace79613a..c2abd20e0734 100644
--- a/drivers/gpu/drm/panel/panel-novatek-nt36672a.c
+++ b/drivers/gpu/drm/panel/panel-novatek-nt36672a.c
@@ -656,14 +656,6 @@ static void nt36672a_panel_remove(struct mipi_dsi_devi=
ce *dsi)
        struct nt36672a_panel *pinfo =3D mipi_dsi_get_drvdata(dsi);
        int err;

-       err =3D drm_panel_unprepare(&pinfo->base);
-       if (err < 0)
-               dev_err(&dsi->dev, "failed to unprepare panel: %d\n", err);
-
-       err =3D drm_panel_disable(&pinfo->base);
-       if (err < 0)
-               dev_err(&dsi->dev, "failed to disable panel: %d\n", err);
-
        err =3D mipi_dsi_detach(dsi);
        if (err < 0)
                dev_err(&dsi->dev, "failed to detach from DSI host: %d\n", =
err);
@@ -671,14 +663,6 @@ static void nt36672a_panel_remove(struct mipi_dsi_devi=
ce *dsi)
        drm_panel_remove(&pinfo->base);
 }

-static void nt36672a_panel_shutdown(struct mipi_dsi_device *dsi)
-{
-       struct nt36672a_panel *pinfo =3D mipi_dsi_get_drvdata(dsi);
-
-       drm_panel_disable(&pinfo->base);
-       drm_panel_unprepare(&pinfo->base);
-}
-
 static const struct of_device_id tianma_fhd_video_of_match[] =3D {
        { .compatible =3D "tianma,fhd-video", .data =3D &tianma_fhd_video_p=
anel_desc },
        { },
@@ -692,7 +676,6 @@ static struct mipi_dsi_driver nt36672a_panel_driver =3D=
 {
        },
        .probe =3D nt36672a_panel_probe,
        .remove =3D nt36672a_panel_remove,
-       .shutdown =3D nt36672a_panel_shutdown,
 };
 module_mipi_dsi_driver(nt36672a_panel_driver);

--
2.45.0.rc1.225.g2a3ae87e7f-goog