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From: Stephen Boyd <swboyd@chromium.org>
To: khsieh@codeaurora.org
Cc: robdclark@gmail.com, sean@poorly.run, abhinavk@codeaurora.org,
	aravindh@codeaurora.org, airlied@linux.ie, daniel@ffwll.ch,
	linux-arm-msm@vger.kernel.org, dri-devel@lists.freedesktop.org,
	freedreno@lists.freedesktop.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 3/3] drm/msm/dp: check main link status before start aux read
Date: Thu, 15 Apr 2021 13:06:29 -0700	[thread overview]
Message-ID: <161851718969.46595.12896385877607476879@swboyd.mtv.corp.google.com> (raw)
In-Reply-To: <60bceecc3d4dcc71c66a4b093d0e6c0f@codeaurora.org>

Quoting khsieh@codeaurora.org (2021-04-15 10:37:29)
> On 2021-04-14 14:09, Stephen Boyd wrote:
> > Quoting Kuogee Hsieh (2021-04-13 16:11:44)
> >> Make sure main link is in connection state before start aux
> >> read/write operation to avoid unnecessary long delay due to
> >> main link had been unplugged.
> >> 
> >> Signed-off-by: Kuogee Hsieh <khsieh@codeaurora.org>
> >> ---
> >>  drivers/gpu/drm/msm/dp/dp_aux.c  |  5 +++++
> >>  drivers/gpu/drm/msm/dp/dp_link.c | 20 +++++++++++++++-----
> >>  2 files changed, 20 insertions(+), 5 deletions(-)
> >> 
> >> diff --git a/drivers/gpu/drm/msm/dp/dp_aux.c 
> >> b/drivers/gpu/drm/msm/dp/dp_aux.c
> >> index 7c22bfe..fae3806 100644
> >> --- a/drivers/gpu/drm/msm/dp/dp_aux.c
> >> +++ b/drivers/gpu/drm/msm/dp/dp_aux.c
> >> @@ -343,6 +343,11 @@ static ssize_t dp_aux_transfer(struct drm_dp_aux 
> >> *dp_aux,
> >> 
> >>         mutex_lock(&aux->mutex);
> >> 
> >> +       if (!dp_catalog_link_is_connected(aux->catalog)) {
> >> +               ret = -ETIMEDOUT;
> >> +               goto unlock_exit;
> >> +       }
> > 
> > I get a crash here sometimes when plugging and unplugging an apple HDMI
> > dongle during suspend/resume. I guess device power management
> > (dp_pm_suspend()) is happening in parallel with aux transfers from the
> > kthread. Why doesn't the aux communication start reporting NAKs once 
> > the
> > cable is disconnected?
> > 
> > [  366.210058] hdmi-audio-codec hdmi-audio-codec.15.auto: calling
> > platform_pm_suspend+0x0/0x60 @ 7175, parent:
> > ae90000.displayport-controller
> > [  366.222825] hdmi-audio-codec hdmi-audio-codec.15.auto:
> > platform_pm_suspend+0x0/0x60 returned 0 after 1 usecs
> > [  366.232939] msm-dp-display ae90000.displayport-controller: calling
> > dp_pm_suspend+0x0/0x80 @ 7175, parent: ae00000.mdss
> > [  366.244006] msm-dp-display ae90000.displayport-controller:
> > dp_pm_suspend+0x0/0x80 returned 0 after 79 usecs
> > [  366.254025] msm_dsi ae94000.dsi: calling
> > pm_runtime_force_suspend+0x0/0xb4 @ 7175, parent: ae00000.mdss
> > [  366.263669] msm_dsi ae94000.dsi: pm_runtime_force_suspend+0x0/0xb4
> > returned 0 after 0 usecs
> > [  366.272290] panel-simple panel: calling
> > platform_pm_suspend+0x0/0x60 @ 7175, parent: platform
> > [  366.272501] ti_sn65dsi86 2-002d: calling
> > pm_runtime_force_suspend+0x0/0xb4 @ 176, parent: i2c-2
> > [  366.281055] panel-simple panel: platform_pm_suspend+0x0/0x60
> > returned 0 after 0 usecs
> > [  366.281081] leds mmc1::: calling led_suspend+0x0/0x4c @ 7175,
> > parent: 7c4000.sdhci
> > [  366.290065] ti_sn65dsi86 2-002d: pm_runtime_force_suspend+0x0/0xb4
> > returned 0 after 0 usecs
> > [  366.298046] leds mmc1::: led_suspend+0x0/0x4c returned 0 after 1 
> > usecs
> > [  366.302994] Internal error: synchronous external abort: 96000010
> > [#1] PREEMPT SMP
> > [  366.303006] Modules linked in: vhost_vsock
> > vmw_vsock_virtio_transport_common vsock vhost rfcomm algif_hash
> > algif_skcipher af_alg xt_cgroup uinput xt_MASQUERADE venus_enc
> > hci_uart venus_dec btqca cros_ec_typec typec bluetooth qcom_spmi_adc5
> > snd_soc_sc7180 qcom_spmi_temp_alarm ecdh_generic qcom_spmi_adc_tm5
> > qcom_vadc_common snd_soc_qcom_common ecc snd_soc_rt5682_i2c
> > snd_soc_rt5682 snd_soc_rl6231 venus_core v4l2_mem2mem
> > snd_soc_lpass_sc7180 snd_soc_lpass_hdmi snd_soc_lpass_cpu
> > snd_soc_lpass_platform snd_soc_max98357a fuse iio_trig_sysfs
> > cros_ec_sensors cros_ec_sensors_ring cros_ec_lid_angle
> > cros_ec_sensors_core industrialio_triggered_buffer kfifo_buf
> > cros_ec_sensorhub lzo_rle lzo_compress zram ath10k_snoc ath10k_core
> > ath mac80211 cfg80211 cdc_ether usbnet r8152 mii uvcvideo
> > videobuf2_vmalloc joydev
> > [  366.303211] CPU: 0 PID: 224 Comm: dp_hpd_handler Not tainted 5.4.109 
> > #27
> > [  366.303216] Hardware name: Google Lazor (rev3+) with KB Backlight 
> > (DT)
> > [  366.303225] pstate: 60c00009 (nZCv daif +PAN +UAO)
> > [  366.303234] pc : dp_catalog_link_is_connected+0x20/0x34
> > [  366.303244] lr : dp_aux_transfer+0x44/0x284
> > [  366.303250] sp : ffffffc011bfbbe0
> > [  366.303254] x29: ffffffc011bfbbe0 x28: aaaaaaaaaaaaaaaa
> > [  366.303262] x27: 000000000000000c x26: ffffff896f8212bc
> > [  366.303269] x25: 0000000000000001 x24: 0000000000000001
> > [  366.303275] x23: 0000000000000020 x22: ffffff896ff82118
> > [  366.303282] x21: ffffffc011bfbc50 x20: ffffff896ff82090
> > [  366.303289] x19: ffffff896ffc3598 x18: 0000000000000000
> > [  366.303295] x17: 0000000000000000 x16: 0000000000000001
> > [  366.303303] x15: 0000000000000000 x14: 00000000000002ef
> > [  366.303311] x13: 0000000000000400 x12: ffffffeb896ea060
> > [  366.303317] x11: 0000000000000000 x10: 0000000000000000
> > [  366.303324] x9 : ffffff896f061100 x8 : ffffffc010582204
> > [  366.303331] x7 : 000000b2b5593519 x6 : 00000000003033ff
> > [  366.303338] x5 : 0000000000000000 x4 : 0000000000000001
> > [  366.303345] x3 : ffffff896ff432a1 x2 : 0000000000000000
> > [  366.303352] x1 : 0000000000000119 x0 : ffffff896ffc3598
> > [  366.303360] Call trace:
> > [  366.303367]  dp_catalog_link_is_connected+0x20/0x34
> > [  366.303374]  dp_aux_transfer+0x44/0x284
> > [  366.303387]  drm_dp_dpcd_access+0x8c/0x11c
> > [  366.303393]  drm_dp_dpcd_read+0x64/0x10c
> > [  366.303399]  dp_link_process_request+0x94/0xaf8
> > [  366.303405]  dp_display_usbpd_attention_cb+0x38/0x140
> > [  366.303411]  hpd_event_thread+0x3f0/0x48c
> > [  366.303426]  kthread+0x140/0x17c
> > [  366.303439]  ret_from_fork+0x10/0x18
> > [  366.303458] Code: d503201f f85f0268 f9400508 91081108 (b9400108)
> > 
> it needs to make sure core clock enabled before access dp ctrl registers
> I am look into it

Is it really necessary to have this patch at all? I think there are
bigger problems with suspend/resume of the DP driver in relation to the
kthread stopping. I hope that the aux channel would start NAKing
transfers once the cable is disconnected too, so that we don't need to
do an extra check for each aux transfer.

  reply	other threads:[~2021-04-15 20:06 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-13 23:11 [PATCH v2 3/3] drm/msm/dp: check main link status before start aux read Kuogee Hsieh
2021-04-14 21:09 ` Stephen Boyd
2021-04-15 17:37   ` khsieh
2021-04-15 20:06     ` Stephen Boyd [this message]
2021-04-15 22:02       ` khsieh
2021-04-15 22:46         ` Stephen Boyd
2021-04-15 23:28           ` [PATCH v3 " Kuogee Hsieh

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