linux-kernel - Re: [PATCH v2 4/4] drm/msm/dpu: don't set crtc_state->mode_changed from atomic

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Message-ID: <vn3f6jzx27twq7maamdmeqahvn4zzoxmdttkm7epg2qgn4ueov@hqzjzzzw3mog>
Date: Wed, 26 Feb 2025 13:55:04 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
	Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, 
	David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, Rob Clark <robdclark@...il.com>, 
	Abhinav Kumar <quic_abhinavk@...cinc.com>, Sean Paul <sean@...rly.run>, 
	Marijn Suijten <marijn.suijten@...ainline.org>, Chandan Uddaraju <chandanu@...eaurora.org>, 
	Jeykumar Sankaran <jsanka@...eaurora.org>, Jordan Crouse <jordan@...micpenguin.net>, 
	Sravanthi Kollukuduru <skolluku@...eaurora.org>
Cc: dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org, 
	Archit Taneja <architt@...eaurora.org>, Rajesh Yadav <ryadav@...eaurora.org>, 
	linux-arm-msm@...r.kernel.org, freedreno@...ts.freedesktop.org, 
	Simona Vetter <simona.vetter@...ll.ch>
Subject: Re: [PATCH v2 4/4] drm/msm/dpu: don't set crtc_state->mode_changed
 from atomic_check()

On Thu, Jan 23, 2025 at 02:43:36PM +0200, Dmitry Baryshkov wrote:
> The MSM driver uses drm_atomic_helper_check() which mandates that none
> of the atomic_check() callbacks toggles crtc_state->mode_changed.
> Perform corresponding check before calling the drm_atomic_helper_check()
> function.
> 
> Fixes: 8b45a26f2ba9 ("drm/msm/dpu: reserve cdm blocks for writeback in case of YUV output")
> Reported-by: Simona Vetter <simona.vetter@...ll.ch>
> Closes: https://lore.kernel.org/dri-devel/ZtW_S0j5AEr4g0QW@phenom.ffwll.local/
> Reviewed-by: Abhinav Kumar <quic_abhinavk@...cinc.com>
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
> ---
>  drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c | 32 +++++++++++++++++++++++++----
>  drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h |  4 ++++
>  drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c     | 26 +++++++++++++++++++++++
>  drivers/gpu/drm/msm/msm_atomic.c            | 13 +++++++++++-
>  drivers/gpu/drm/msm/msm_kms.h               |  7 +++++++
>  5 files changed, 77 insertions(+), 5 deletions(-)
> 

JFI, this patch generates following warnings, deferred now:

10:49:07.279: [  235.096198] WARNING: CPU: 1 PID: 515 at drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c:459 dpu_kms_check_mode_changed+0xb0/0xbc
10:49:07.279: [  235.107375] Modules linked in:
10:49:07.279: [  235.110532] CPU: 1 UID: 0 PID: 515 Comm: kms_atomic_tran Tainted: G        W          6.14.0-rc4-gd229bc98da6b #1
10:49:07.279: [  235.121069] Tainted: [W]=WARN
10:49:07.279: [  235.124130] Hardware name: Google Lazor Limozeen without Touchscreen (rev5 - rev8) (DT)
10:49:07.279: [  235.132356] pstate: 20400009 (nzCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
10:49:07.279: [  235.139513] pc : dpu_kms_check_mode_changed+0xb0/0xbc
10:49:07.279: [  235.144712] lr : msm_atomic_check+0xc0/0xe0
10:49:07.279: [  235.149023] sp : ffff8000843f3960
10:49:07.279: [  235.150686] usb 1-1.1: new high-speed USB device number 100 using xhci-hcd
10:49:07.279: [  235.152439] x29: ffff8000843f3960 x28: ffff65a18386d080 x27: ffff65a184826a80
10:49:07.279: [  235.166848] x26: 0000000000000038 x25: 0000000000000008 x24: ffff65a1866fd580
10:49:07.279: [  235.174188] x23: 0000000000000028 x22: 0000000000000028 x21: 0000000000000038
10:49:07.279: [  235.181527] x20: ffff65a184826a80 x19: 0000000000000000 x18: 0000000000000000
10:49:07.279: [  235.188866] x17: 0000000000000000 x16: 0000000000000000 x15: 0000aaab013dfeb8
10:49:07.279: [  235.196215] x14: 00000000000c0000 x13: 0040a00000400800 x12: 0000000000000000
10:49:07.279: [  235.203553] x11: 0000000000000050 x10: 0000000000000000 x9 : ffffbdf7fc448530
10:49:07.279: [  235.210892] x8 : 00000000ffffffff x7 : ffff65a182610400 x6 : 0000000000000038
10:49:07.279: [  235.218231] x5 : ffff65a18314b000 x4 : 0000000000000000 x3 : 0000000000000001
10:49:07.279: [  235.225570] x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff65a18ca7a600
10:49:07.279: [  235.232910] Call trace:
10:49:07.279: [  235.235440]  dpu_kms_check_mode_changed+0xb0/0xbc (P)
10:49:07.279: [  235.240641]  msm_atomic_check+0xc0/0xe0
10:49:07.279: [  235.244594]  drm_atomic_check_only+0x498/0x934
10:49:07.279: [  235.249169]  drm_atomic_commit+0x48/0xc4
10:49:07.279: [  235.253209]  drm_mode_atomic_ioctl+0xa98/0xd00
10:49:07.279: [  235.257791]  drm_ioctl_kernel+0xbc/0x12c
10:49:07.280: [  235.261832]  drm_ioctl+0x228/0x4e4
10:49:07.280: [  235.265339]  __arm64_sys_ioctl+0xb4/0xec
10:49:07.280: [  235.269381]  invoke_syscall+0x48/0x110
10:49:07.280: [  235.273248]  el0_svc_common.constprop.0+0x40/0xe0
10:49:07.280: [  235.278090]  do_el0_svc+0x1c/0x28
10:49:07.280: [  235.281512]  el0_svc+0x48/0x110
10:49:07.280: [  235.284753]  el0t_64_sync_handler+0x10c/0x138
10:49:07.280: [  235.289234]  el0t_64_sync+0x198/0x19c


-- 
With best wishes
Dmitry