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From: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Maxime Ripard <maxime@cerno.tech>, Emma Anholt <emma@anholt.net>,
	David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>,
	Philipp Zabel <p.zabel@pengutronix.de>,
	dri-devel <dri-devel@lists.freedesktop.org>,
	linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: Regression with mainline kernel on rpi4
Date: Wed, 22 Sep 2021 21:19:06 +0100	[thread overview]
Message-ID: <CADVatmPDeSxeY3GTZyC6+G0N76su0E6Y3LF_h6BOcBf5QAtjvg@mail.gmail.com> (raw)
In-Reply-To: <CAHk-=wh+y=C5hVhE1X=AvZz+OM5Yp8eLHYGth31pfoJVF7UKKQ@mail.gmail.com>

On Wed, Sep 22, 2021 at 7:23 PM Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> On Wed, Sep 22, 2021 at 10:02 AM Sudip Mukherjee
> <sudipm.mukherjee@gmail.com> wrote:
> >
> >
> > Attached is a complete dmesg and also the decoded trace.
> > This is done on 4357f03d6611 ("Merge tag 'pm-5.15-rc2' of
> > git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm")
>
> drivers/gpu/drm/vc4/vc4_hdmi.c:1214 is
>
>         tmp = (u64)(mode->clock * 1000) * n;
>
> in vc4_hdmi_set_n_cts(), which has apparently been inlined from
> vc4_hdmi_audio_prepare() in vc4_hdmi.c:1398.
>
> So it looks like 'mode' is some offset off a NULL pointer.
>
> Which looks not impossible:
>
>   1207          struct drm_connector *connector = &vc4_hdmi->connector;
>   1208          struct drm_crtc *crtc = connector->state->crtc;
>   1209          const struct drm_display_mode *mode =
> &crtc->state->adjusted_mode;
>
> looks like crtc->state perhaps might be NULL.

I added some debugs to print the addresses, and I am getting:
[   38.813809] sudip crtc 0000000000000000

This is from struct drm_crtc *crtc = connector->state->crtc;

connector and connector->state had valid addresses.
[   38.805302] sudip connector ffff000040bac578
[   38.809779] sudip state ffff000057eb5400

This is the diff of the debug I added:
diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
index 4a1115043114..2a8f06948094 100644
--- a/drivers/gpu/drm/vc4/vc4_hdmi.c
+++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
@@ -1205,11 +1205,20 @@ static void
vc4_hdmi_audio_set_mai_clock(struct vc4_hdmi *vc4_hdmi,
 static void vc4_hdmi_set_n_cts(struct vc4_hdmi *vc4_hdmi, unsigned
int samplerate)
 {
        struct drm_connector *connector = &vc4_hdmi->connector;
-       struct drm_crtc *crtc = connector->state->crtc;
-       const struct drm_display_mode *mode = &crtc->state->adjusted_mode;
+       struct drm_crtc *crtc;
+       struct drm_display_mode *mode;
        u32 n, cts;
        u64 tmp;

+
+       pr_err("sudip connector %px\n", connector);
+       pr_err("sudip state %px\n", connector->state);
+       crtc = connector->state->crtc;
+
+       pr_err("sudip crtc %px\n", crtc);
+       pr_err("sudip state %px\n", crtc->state);
+       pr_err("state mode %px\n", &crtc->state->adjusted_mode);
+       mode = &crtc->state->adjusted_mode;
        n = 128 * samplerate / 1000;
        tmp = (u64)(mode->clock * 1000) * n;
        do_div(tmp, 128 * samplerate);


-- 
Regards
Sudip

  reply	other threads:[~2021-09-22 20:19 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-02  9:08 Sudip Mukherjee
2021-09-02  9:08 ` Sudip Mukherjee
2021-09-03 16:03 ` Maxime Ripard
2021-09-03 20:09   ` Sudip Mukherjee
2021-09-03 20:09     ` Sudip Mukherjee
2021-09-04  9:10     ` Maxime Ripard
2021-09-04  9:40       ` Sudip Mukherjee
2021-09-04  9:40         ` Sudip Mukherjee
2021-09-20 14:47         ` Maxime Ripard
2021-09-20 15:43           ` Maxime Ripard
2021-09-20 15:53             ` Maxime Ripard
2021-09-20 16:35               ` Sudip Mukherjee
2021-09-20 16:35                 ` Sudip Mukherjee
2021-09-20 17:10                 ` Maxime Ripard
2021-09-20 17:21                   ` Sudip Mukherjee
2021-09-20 17:21                     ` Sudip Mukherjee
2021-09-22  9:57                     ` Maxime Ripard
2021-09-22 10:10                       ` Sudip Mukherjee
2021-09-22 10:10                         ` Sudip Mukherjee
2021-09-22 11:28                         ` Maxime Ripard
2021-09-22 17:18                           ` Sudip Mukherjee
2021-09-22 17:18                             ` Sudip Mukherjee
2021-09-22 15:22                         ` Linus Torvalds
2021-09-22 15:22                           ` Linus Torvalds
2021-09-22 17:02                           ` Sudip Mukherjee
2021-09-22 17:02                             ` Sudip Mukherjee
2021-09-22 18:23                             ` Linus Torvalds
2021-09-22 18:23                               ` Linus Torvalds
2021-09-22 20:19                               ` Sudip Mukherjee [this message]
2021-09-22 20:19                                 ` Sudip Mukherjee
2021-09-22 20:25                                 ` Linus Torvalds
2021-09-22 20:25                                   ` Linus Torvalds
2021-09-24 13:30                                   ` Maxime Ripard
2021-09-24 22:50                                     ` Daniel Vetter
2021-09-24 22:50                                       ` Daniel Vetter
2021-09-28  8:34                                       ` Maxime Ripard
2021-09-30  9:19                                         ` Daniel Vetter
2021-10-13 15:01                                           ` Maxime Ripard
2021-10-14 13:15                                             ` Daniel Vetter
2021-10-25 14:15                                               ` Maxime Ripard

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