drm/vc4: hdmi: Warn if we access the controller while disabled

We've had many silent hangs where the kernel would look like it just
stalled due to the access to one of the HDMI registers while the
controller was disabled.

Add a warning if we're about to do that so that it's at least not silent
anymore.

Reviewed-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://patchwork.freedesktop.org/patch/msgid/20210819135931.895976-7-maxime@cerno.tech

diff --git a/drivers/gpu/drm/vc4/vc4_hdmi_regs.h b/drivers/gpu/drm/vc4/vc4_hdmi_regs.h
index 19d2fdc446bcac738530b9c0732c6ebf4978cece..99dde6e06a3788c4d1da61ff526d286120094c2f 100644 (file)
--- a/drivers/gpu/drm/vc4/vc4_hdmi_regs.h
+++ b/drivers/gpu/drm/vc4/vc4_hdmi_regs.h
@@ -1,6 +1,8 @@
 #ifndef _VC4_HDMI_REGS_H_
 #define _VC4_HDMI_REGS_H_
 
+#include <linux/pm_runtime.h>
+
 #include "vc4_hdmi.h"
 
 #define VC4_HDMI_PACKET_STRIDE                 0x24
@@ -412,6 +414,8 @@ static inline u32 vc4_hdmi_read(struct vc4_hdmi *hdmi,
        const struct vc4_hdmi_variant *variant = hdmi->variant;
        void __iomem *base;
 
+       WARN_ON(!pm_runtime_active(&hdmi->pdev->dev));
+
        if (reg >= variant->num_registers) {
                dev_warn(&hdmi->pdev->dev,
                         "Invalid register ID %u\n", reg);
@@ -438,6 +442,8 @@ static inline void vc4_hdmi_write(struct vc4_hdmi *hdmi,
        const struct vc4_hdmi_variant *variant = hdmi->variant;
        void __iomem *base;
 
+       WARN_ON(!pm_runtime_active(&hdmi->pdev->dev));
+
        if (reg >= variant->num_registers) {
                dev_warn(&hdmi->pdev->dev,
                         "Invalid register ID %u\n", reg);