linux-kernel - Re: [RFT PATCH v2 19/48] drm/panel: novatek-nt36672a: Don't call unprepare+disable at shutdown/remove

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Date: Sat, 4 May 2024 23:58:11 +0000
From: Joel Selvaraj <jo@...amily.in>
To: Douglas Anderson <dianders@...omium.org>,
	"dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>, Maxime
 Ripard <mripard@...nel.org>
CC: Linus Walleij <linus.walleij@...aro.org>, Chris Morgan
	<macromorgan@...mail.com>, Yuran Pereira <yuran.pereira@...mail.com>, Neil
 Armstrong <neil.armstrong@...aro.org>, Sumit Semwal
	<sumit.semwal@...aro.org>, Benni Steini <bennisteinir@...il.com>, Marijn
 Suijten <marijn.suijten@...ainline.org>, Daniel Vetter <daniel@...ll.ch>,
	David Airlie <airlied@...il.com>, Jessica Zhang <quic_jesszhan@...cinc.com>,
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, Sam Ravnborg
	<sam@...nborg.org>, Thomas Zimmermann <tzimmermann@...e.de>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [RFT PATCH v2 19/48] drm/panel: novatek-nt36672a: Don't call
 unprepare+disable at shutdown/remove

Hi Douglas Anderson,

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

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

Regards
Joel Selvaraj

________________________________________
From: Douglas Anderson <dianders@...omium.org>
Sent: 04 May 2024 03:03
To: dri-devel@...ts.freedesktop.org; Maxime Ripard
Cc: Linus Walleij; Chris Morgan; Yuran Pereira; Neil Armstrong; Douglas Anderson; Sumit Semwal; Benni Steini; Joel Selvaraj; Marijn Suijten; Daniel Vetter; David Airlie; Jessica Zhang; Maarten Lankhorst; Sam Ravnborg; Thomas Zimmermann; linux-kernel@...r.kernel.org
Subject: [RFT PATCH v2 19/48] drm/panel: novatek-nt36672a: Don't call unprepare+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.org

Cc: Sumit Semwal <sumit.semwal@...aro.org>
Cc: Benni Steini <bennisteinir@...il.com>
Cc: Joel Selvaraj <jo@...amily.in>
Cc: Marijn Suijten <marijn.suijten@...ainline.org>
Signed-off-by: Douglas Anderson <dianders@...omium.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/drm/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_device *dsi)
        struct nt36672a_panel *pinfo = mipi_dsi_get_drvdata(dsi);
        int err;

-       err = drm_panel_unprepare(&pinfo->base);
-       if (err < 0)
-               dev_err(&dsi->dev, "failed to unprepare panel: %d\n", err);
-
-       err = drm_panel_disable(&pinfo->base);
-       if (err < 0)
-               dev_err(&dsi->dev, "failed to disable panel: %d\n", err);
-
        err = 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_device *dsi)
        drm_panel_remove(&pinfo->base);
 }

-static void nt36672a_panel_shutdown(struct mipi_dsi_device *dsi)
-{
-       struct nt36672a_panel *pinfo = 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[] = {
        { .compatible = "tianma,fhd-video", .data = &tianma_fhd_video_panel_desc },
        { },
@@ -692,7 +676,6 @@ static struct mipi_dsi_driver nt36672a_panel_driver = {
        },
        .probe = nt36672a_panel_probe,
        .remove = nt36672a_panel_remove,
-       .shutdown = nt36672a_panel_shutdown,
 };
 module_mipi_dsi_driver(nt36672a_panel_driver);

--
2.45.0.rc1.225.g2a3ae87e7f-goog