target/linux/bcm27xx/patches-5.15/950-0003-drm-vc4-hdmi-Warn-if-we-access-the-controller-while-.patch

   1 From d0a44f399526a061e74b9a34b554f3d0e9cdddb3 Mon Sep 17 00:00:00 2001
   2 From: Maxime Ripard <maxime@cerno.tech>
   3 Date: Thu, 19 Aug 2021 15:59:31 +0200
   4 Subject: [PATCH] drm/vc4: hdmi: Warn if we access the controller while
   5  disabled
   6
   7 We've had many silent hangs where the kernel would look like it just
   8 stalled due to the access to one of the HDMI registers while the
   9 controller was disabled.
  10
  11 Add a warning if we're about to do that so that it's at least not silent
  12 anymore.
  13
  14 Reviewed-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
  15 Signed-off-by: Maxime Ripard <maxime@cerno.tech>
  16 Link: https://patchwork.freedesktop.org/patch/msgid/20210819135931.895976-7-maxime@cerno.tech
  17 ---
  18  drivers/gpu/drm/vc4/vc4_hdmi_regs.h | 6 ++++++
  19  1 file changed, 6 insertions(+)
  20
  21 --- a/drivers/gpu/drm/vc4/vc4_hdmi_regs.h
  22 +++ b/drivers/gpu/drm/vc4/vc4_hdmi_regs.h
  23 @@ -1,6 +1,8 @@
  24  #ifndef _VC4_HDMI_REGS_H_
  25  #define _VC4_HDMI_REGS_H_
  26
  27 +#include <linux/pm_runtime.h>
  28 +
  29  #include "vc4_hdmi.h"
  30
  31  #define VC4_HDMI_PACKET_STRIDE                 0x24
  32 @@ -412,6 +414,8 @@ static inline u32 vc4_hdmi_read(struct v
  33         const struct vc4_hdmi_variant *variant = hdmi->variant;
  34         void __iomem *base;
  35
  36 +       WARN_ON(!pm_runtime_active(&hdmi->pdev->dev));
  37 +
  38         if (reg >= variant->num_registers) {
  39                 dev_warn(&hdmi->pdev->dev,
  40                          "Invalid register ID %u\n", reg);
  41 @@ -438,6 +442,8 @@ static inline void vc4_hdmi_write(struct
  42         const struct vc4_hdmi_variant *variant = hdmi->variant;
  43         void __iomem *base;
  44
  45 +       WARN_ON(!pm_runtime_active(&hdmi->pdev->dev));
  46 +
  47         if (reg >= variant->num_registers) {
  48                 dev_warn(&hdmi->pdev->dev,
  49                          "Invalid register ID %u\n", reg);