linux-kernel - [PATCH 08/10] drm/tidss: Add dispc_is

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Message-Id: <20231101-tidss-probe-v1-8-45149e0f9415@ideasonboard.com>
Date:   Wed, 01 Nov 2023 11:17:45 +0200
From:   Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
To:     Aradhya Bhatia <a-bhatia1@...com>,
        Devarsh Thakkar <devarsht@...com>,
        Jyri Sarha <jyri.sarha@....fi>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>
Cc:     dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
Subject: [PATCH 08/10] drm/tidss: Add dispc_is_idle()

Add a helper function, dispc_is_idle(), which returns whether the DSS is
idle (i.e. is any video port enabled).

For now we add a call to it in the suspend and resume callbacks, and
print a warning if in either place the DSS is not idle. In the future
this can be used to detect if the bootloader had enabled the DSS, and
the driver can act on that.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
---
 drivers/gpu/drm/tidss/tidss_dispc.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/gpu/drm/tidss/tidss_dispc.c b/drivers/gpu/drm/tidss/tidss_dispc.c
index 13db062892e3..a527c28c8833 100644
--- a/drivers/gpu/drm/tidss/tidss_dispc.c
+++ b/drivers/gpu/drm/tidss/tidss_dispc.c
@@ -2603,10 +2603,18 @@ void dispc_vp_setup(struct dispc_device *dispc, u32 hw_videoport,
 	dispc_vp_set_color_mgmt(dispc, hw_videoport, state, newmodeset);
 }
 
+static bool dispc_is_idle(struct dispc_device *dispc)
+{
+	return REG_GET(dispc, DSS_SYSSTATUS, 9, 9);
+}
+
 int dispc_runtime_suspend(struct dispc_device *dispc)
 {
 	dev_dbg(dispc->dev, "suspend\n");
 
+	if (!dispc_is_idle(dispc))
+		dev_warn(dispc->dev, "Bad HW state: DSS not idle when suspending");
+
 	dispc->is_enabled = false;
 
 	clk_disable_unprepare(dispc->fclk);
@@ -2620,6 +2628,9 @@ int dispc_runtime_resume(struct dispc_device *dispc)
 
 	clk_prepare_enable(dispc->fclk);
 
+	if (!dispc_is_idle(dispc))
+		dev_warn(dispc->dev, "Bad HW state: DSS not idle when resuming");
+
 	if (REG_GET(dispc, DSS_SYSSTATUS, 0, 0) == 0)
 		dev_warn(dispc->dev, "DSS FUNC RESET not done!\n");
 

-- 
2.34.1