linux-kernel - [RFT PATCH 12/15] drm/gma500: Call drm_helper_force_disable

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Message-ID: <20230901164111.RFT.12.I1be622999c3b23f28f077fc75bb0319396a216e9@changeid>
Date:   Fri,  1 Sep 2023 16:41:23 -0700
From:   Douglas Anderson <dianders@...omium.org>
To:     dri-devel@...ts.freedesktop.org, Maxime Ripard <mripard@...nel.org>
Cc:     Douglas Anderson <dianders@...omium.org>, airlied@...il.com,
        daniel@...ll.ch, linux-kernel@...r.kernel.org,
        patrik.r.jakobsson@...il.com
Subject: [RFT PATCH 12/15] drm/gma500: Call drm_helper_force_disable_all() at shutdown/remove time

Based on grepping through the source code, this driver appears to be
missing a call to drm_atomic_helper_shutdown(), or in this case the
non-atomic equivalent drm_helper_force_disable_all(), at system
shutdown time and at driver remove time. This is important because
drm_helper_force_disable_all() will cause panels to get disabled
cleanly which may be important for their power sequencing. Future
changes will remove any custom powering off in individual panel
drivers so the DRM drivers need to start getting this right.

The fact that we should call drm_atomic_helper_shutdown(), or in this
case the non-atomic equivalent drm_helper_force_disable_all(), in the
case of OS shutdown/restart comes straight out of the kernel doc
"driver instance overview" in drm_drv.c.

Suggested-by: Maxime Ripard <mripard@...nel.org>
Signed-off-by: Douglas Anderson <dianders@...omium.org>
---
This commit is only compile-time tested.

 drivers/gpu/drm/gma500/psb_drv.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/gpu/drm/gma500/psb_drv.c b/drivers/gpu/drm/gma500/psb_drv.c
index 8b64f61ffaf9..a5a399bbe8f5 100644
--- a/drivers/gpu/drm/gma500/psb_drv.c
+++ b/drivers/gpu/drm/gma500/psb_drv.c
@@ -20,6 +20,7 @@
 #include <acpi/video.h>

 #include <drm/drm.h>
+#include <drm/drm_crtc_helper.h>
 #include <drm/drm_drv.h>
 #include <drm/drm_file.h>
 #include <drm/drm_ioctl.h>
@@ -485,6 +486,12 @@ static void psb_pci_remove(struct pci_dev *pdev)
 	struct drm_device *dev = pci_get_drvdata(pdev);

 	drm_dev_unregister(dev);
+	drm_helper_force_disable_all(dev);
+}
+
+static void psb_pci_shutdown(struct pci_dev *pdev)
+{
+	drm_helper_force_disable_all(pci_get_drvdata(pdev));
 }

 static DEFINE_RUNTIME_DEV_PM_OPS(psb_pm_ops, gma_power_suspend, gma_power_resume, NULL);
@@ -521,6 +528,7 @@ static struct pci_driver psb_pci_driver = {
 	.id_table = pciidlist,
 	.probe = psb_pci_probe,
 	.remove = psb_pci_remove,
+	.shutdown = psb_pci_shutdown,
 	.driver.pm = &psb_pm_ops,
 };

-- 
2.42.0.283.g2d96d420d3-goog