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Subject: Re: [PATCH] drm/amd/dm/mst: Ignore payload update failures on disable
To:     Harry Wentland <hwentlan@amd.com>, Lyude Paul <lyude@redhat.com>,
        amd-gfx@lists.freedesktop.org
Cc:     stable@vger.kernel.org, Harry Wentland <harry.wentland@amd.com>,
        Leo Li <sunpeng.li@amd.com>,
        Alex Deucher <alexander.deucher@amd.com>,
        =?UTF-8?Q?Christian_K=c3=b6nig?= <christian.koenig@amd.com>,
        "David (ChunMing) Zhou" <David1.Zhou@amd.com>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>,
        Mikita Lipski <mikita.lipski@amd.com>,
        Sam Ravnborg <sam@ravnborg.org>,
        David Francis <David.Francis@amd.com>,
        Martin Tsai <martin.tsai@amd.com>,
        Chris Wilson <chris@chris-wilson.co.uk>,
        Alvin Lee <alvin.lee2@amd.com>,
        Jean Delvare <jdelvare@suse.de>,
        dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org,
        "Lin, Wayne" <Wayne.Lin@amd.com>
References: <20200124000643.99859-1-lyude@redhat.com>
 <41187639-f077-0212-aa02-d5dcc96c442b@amd.com>
From:   Mikita Lipski <mlipski@amd.com>
Organization: AMD
Message-ID: <4ddde071-356b-77a0-25e8-26c22e0ffa14@amd.com>
Date:   Fri, 24 Jan 2020 11:39:54 -0500
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On 1/24/20 9:55 AM, Harry Wentland wrote:
> On 2020-01-23 7:06 p.m., Lyude Paul wrote:
>> Disabling a display on MST can potentially happen after the entire MST
>> topology has been removed, which means that we can't communicate with
>> the topology at all in this scenario. Likewise, this also means that we
>> can't properly update payloads on the topology and as such, it's a good
>> idea to ignore payload update failures when disabling displays.
>> Currently, amdgpu makes the mistake of halting the payload update
>> process when any payload update failures occur, resulting in leaving
>> DC's local copies of the payload tables out of date.
>>
>> This ends up causing problems with hotplugging MST topologies, and
>> causes modesets on the second hotplug to fail like so:
>>
>> [drm] Failed to updateMST allocation table forpipe idx:1
>> ------------[ cut here ]------------
>> WARNING: CPU: 5 PID: 1511 at
>> drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_link.c:2677
>> update_mst_stream_alloc_table+0x11e/0x130 [amdgpu]
>> Modules linked in: cdc_ether usbnet fuse xt_conntrack nf_conntrack
>> nf_defrag_ipv6 libcrc32c nf_defrag_ipv4 ipt_REJECT nf_reject_ipv4
>> nft_counter nft_compat nf_tables nfnetlink tun bridge stp llc sunrpc
>> vfat fat wmi_bmof uvcvideo snd_hda_codec_realtek snd_hda_codec_generic
>> snd_hda_codec_hdmi videobuf2_vmalloc snd_hda_intel videobuf2_memops
>> videobuf2_v4l2 snd_intel_dspcfg videobuf2_common crct10dif_pclmul
>> snd_hda_codec videodev crc32_pclmul snd_hwdep snd_hda_core
>> ghash_clmulni_intel snd_seq mc joydev pcspkr snd_seq_device snd_pcm
>> sp5100_tco k10temp i2c_piix4 snd_timer thinkpad_acpi ledtrig_audio snd
>> wmi soundcore video i2c_scmi acpi_cpufreq ip_tables amdgpu(O)
>> rtsx_pci_sdmmc amd_iommu_v2 gpu_sched mmc_core i2c_algo_bit ttm
>> drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops cec drm
>> crc32c_intel serio_raw hid_multitouch r8152 mii nvme r8169 nvme_core
>> rtsx_pci pinctrl_amd
>> CPU: 5 PID: 1511 Comm: gnome-shell Tainted: G           O      5.5.0-rc7Lyude-Test+ #4
>> Hardware name: LENOVO FA495SIT26/FA495SIT26, BIOS R12ET22W(0.22 ) 01/31/2019
>> RIP: 0010:update_mst_stream_alloc_table+0x11e/0x130 [amdgpu]
>> Code: 28 00 00 00 75 2b 48 8d 65 e0 5b 41 5c 41 5d 41 5e 5d c3 0f b6 06
>> 49 89 1c 24 41 88 44 24 08 0f b6 46 01 41 88 44 24 09 eb 93 <0f> 0b e9
>> 2f ff ff ff e8 a6 82 a3 c2 66 0f 1f 44 00 00 0f 1f 44 00
>> RSP: 0018:ffffac428127f5b0 EFLAGS: 00010202
>> RAX: 0000000000000002 RBX: ffff8d1e166eee80 RCX: 0000000000000000
>> RDX: ffffac428127f668 RSI: ffff8d1e166eee80 RDI: ffffac428127f610
>> RBP: ffffac428127f640 R08: ffffffffc03d94a8 R09: 0000000000000000
>> R10: ffff8d1e24b02000 R11: ffffac428127f5b0 R12: ffff8d1e1b83d000
>> R13: ffff8d1e1bea0b08 R14: 0000000000000002 R15: 0000000000000002
>> FS:  00007fab23ffcd80(0000) GS:ffff8d1e28b40000(0000) knlGS:0000000000000000
>> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>> CR2: 00007f151f1711e8 CR3: 00000005997c0000 CR4: 00000000003406e0
>> Call Trace:
>>   ? mutex_lock+0xe/0x30
>>   dc_link_allocate_mst_payload+0x9a/0x210 [amdgpu]
>>   ? dm_read_reg_func+0x39/0xb0 [amdgpu]
>>   ? core_link_enable_stream+0x656/0x730 [amdgpu]
>>   core_link_enable_stream+0x656/0x730 [amdgpu]
>>   dce110_apply_ctx_to_hw+0x58e/0x5d0 [amdgpu]
>>   ? dcn10_verify_allow_pstate_change_high+0x1d/0x280 [amdgpu]
>>   ? dcn10_wait_for_mpcc_disconnect+0x3c/0x130 [amdgpu]
>>   dc_commit_state+0x292/0x770 [amdgpu]
>>   ? add_timer+0x101/0x1f0
>>   ? ttm_bo_put+0x1a1/0x2f0 [ttm]
>>   amdgpu_dm_atomic_commit_tail+0xb59/0x1ff0 [amdgpu]
>>   ? amdgpu_move_blit.constprop.0+0xb8/0x1f0 [amdgpu]
>>   ? amdgpu_bo_move+0x16d/0x2b0 [amdgpu]
>>   ? ttm_bo_handle_move_mem+0x118/0x570 [ttm]
>>   ? ttm_bo_validate+0x134/0x150 [ttm]
>>   ? dm_plane_helper_prepare_fb+0x1b9/0x2a0 [amdgpu]
>>   ? _cond_resched+0x15/0x30
>>   ? wait_for_completion_timeout+0x38/0x160
>>   ? _cond_resched+0x15/0x30
>>   ? wait_for_completion_interruptible+0x33/0x190
>>   commit_tail+0x94/0x130 [drm_kms_helper]
>>   drm_atomic_helper_commit+0x113/0x140 [drm_kms_helper]
>>   drm_atomic_helper_set_config+0x70/0xb0 [drm_kms_helper]
>>   drm_mode_setcrtc+0x194/0x6a0 [drm]
>>   ? _cond_resched+0x15/0x30
>>   ? mutex_lock+0xe/0x30
>>   ? drm_mode_getcrtc+0x180/0x180 [drm]
>>   drm_ioctl_kernel+0xaa/0xf0 [drm]
>>   drm_ioctl+0x208/0x390 [drm]
>>   ? drm_mode_getcrtc+0x180/0x180 [drm]
>>   amdgpu_drm_ioctl+0x49/0x80 [amdgpu]
>>   do_vfs_ioctl+0x458/0x6d0
>>   ksys_ioctl+0x5e/0x90
>>   __x64_sys_ioctl+0x16/0x20
>>   do_syscall_64+0x55/0x1b0
>>   entry_SYSCALL_64_after_hwframe+0x44/0xa9
>> RIP: 0033:0x7fab2121f87b
>> Code: 0f 1e fa 48 8b 05 0d 96 2c 00 64 c7 00 26 00 00 00 48 c7 c0 ff ff
>> ff ff c3 66 0f 1f 44 00 00 f3 0f 1e fa b8 10 00 00 00 0f 05 <48> 3d 01
>> f0 ff ff 73 01 c3 48 8b 0d dd 95 2c 00 f7 d8 64 89 01 48
>> RSP: 002b:00007ffd045f9068 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
>> RAX: ffffffffffffffda RBX: 00007ffd045f90a0 RCX: 00007fab2121f87b
>> RDX: 00007ffd045f90a0 RSI: 00000000c06864a2 RDI: 000000000000000b
>> RBP: 00007ffd045f90a0 R08: 0000000000000000 R09: 000055dbd2985d10
>> R10: 000055dbd2196280 R11: 0000000000000246 R12: 00000000c06864a2
>> R13: 000000000000000b R14: 0000000000000000 R15: 000055dbd2196280
>> ---[ end trace 6ea888c24d2059cd ]---
>>
>> Note as well, I have only been able to reproduce this on setups with 2
>> MST displays.
>>
>> Signed-off-by: Lyude Paul <lyude@redhat.com>
>> Cc: stable@vger.kernel.org
> 
> LGTM but would like Mikita or Wayne to have a look as well.
> Acked-by: Harry Wentland <harry.wentland@amd.com>


I think its a good change and it definetely helps to deal with 
discreptency between drm and dc payload allocation tables.
But I think we might not even need extra enable checks.

> 
> Harry
> 
>> ---
>>   drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c | 7 ++++---
>>   1 file changed, 4 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
>> index 069b7a6f5597..252fa60c6775 100644
>> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
>> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
>> @@ -216,6 +216,7 @@ bool dm_helpers_dp_mst_write_payload_allocation_table(
>>   		drm_dp_mst_reset_vcpi_slots(mst_mgr, mst_port);
>>   	}
>>   
>> +	/* If disabling, it's OK for this to fail */
>>   	ret = drm_dp_update_payload_part1(mst_mgr);
>>   
>>   	/* mst_mgr->->payloads are VC payload notify MST branch using DPCD or
>> @@ -225,7 +226,7 @@ bool dm_helpers_dp_mst_write_payload_allocation_table(
>>   
>>   	get_payload_table(aconnector, proposed_table);
>>   
>> -	if (ret)
>> +	if (ret && !enable)
>>   		return false;

Wouldn't it be better to check ret value, and instead of returning false 
just throw DRM_ERROR message, since drm_dp_update_payload_part1 only 
returns error if a port is not validated?

Thank you,
Mikita

>>   
>>   	return true;
>> @@ -299,9 +300,9 @@ bool dm_helpers_dp_mst_send_payload_allocation(
>>   	if (!mst_mgr->mst_state)
>>   		return false;
>>   
>> +	/* If disabling, it's OK for this to fail */
>>   	ret = drm_dp_update_payload_part2(mst_mgr);
>> -
>> -	if (ret)
>> +	if (enable && ret)
>>   		return false;
>>   
>>   	if (!enable)