From mboxrd@z Thu Jan 1 00:00:00 1970 From: dhar@codeaurora.org Subject: Re: drm/msm/dpu: Correct dpu encoder spinlock initialization Date: Tue, 25 Jun 2019 11:14:45 +0530 Message-ID: References: <1561357632-15361-1-git-send-email-dhar@codeaurora.org> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Jeykumar Sankaran Cc: dri-devel@lists.freedesktop.org, linux-arm-msm@vger.kernel.org, freedreno@lists.freedesktop.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, robdclark@gmail.com, seanpaul@chromium.org, hoegsberg@chromium.org, abhinavk@codeaurora.org, chandanu@codeaurora.org, nganji@codeaurora.org, jshekhar@codeaurora.org List-Id: devicetree@vger.kernel.org On 2019-06-25 03:56, Jeykumar Sankaran wrote: > On 2019-06-23 23:27, Shubhashree Dhar wrote: >> dpu encoder spinlock should be initialized during dpu encoder >> init instead of dpu encoder setup which is part of commit. >> There are chances that vblank control uses the uninitialized >> spinlock if not initialized during encoder init. > Not much can be done if someone is performing a vblank operation > before encoder_setup is done. > Can you point to the path where this lock is acquired before > the encoder_setup? > > Thanks > Jeykumar S. >> When running some dp usecase, we are hitting this callstack. Process kworker/u16:8 (pid: 215, stack limit = 0x00000000df9dd930) Call trace: spin_dump+0x84/0x8c spin_dump+0x0/0x8c do_raw_spin_lock+0x80/0xb0 _raw_spin_lock_irqsave+0x34/0x44 dpu_encoder_toggle_vblank_for_crtc+0x8c/0xe8 dpu_crtc_vblank+0x168/0x1a0 dpu_kms_enable_vblank+0[ 11.648998] vblank_ctrl_worker+0x3c/0x60 process_one_work+0x16c/0x2d8 worker_thread+0x1d8/0x2b0 kthread+0x124/0x134 Looks like vblank is getting enabled earlier causing this issue and we are using the spinlock without initializing it. Thanks, Shubhashree >> Change-Id: I5a18b95fa47397c834a266b22abf33a517b03a4e >> Signed-off-by: Shubhashree Dhar >> --- >> drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c | 3 +-- >> 1 file changed, 1 insertion(+), 2 deletions(-) >> >> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c >> b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c >> index 5f085b5..22938c7 100644 >> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c >> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c >> @@ -2195,8 +2195,6 @@ int dpu_encoder_setup(struct drm_device *dev, >> struct >> drm_encoder *enc, >> if (ret) >> goto fail; >> >> - spin_lock_init(&dpu_enc->enc_spinlock); >> - >> atomic_set(&dpu_enc->frame_done_timeout, 0); >> timer_setup(&dpu_enc->frame_done_timer, >> dpu_encoder_frame_done_timeout, 0); >> @@ -2250,6 +2248,7 @@ struct drm_encoder *dpu_encoder_init(struct >> drm_device *dev, >> >> drm_encoder_helper_add(&dpu_enc->base, &dpu_encoder_helper_funcs); >> >> + spin_lock_init(&dpu_enc->enc_spinlock); >> dpu_enc->enabled = false; >> >> return &dpu_enc->base;