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);