Re: [PATCH v6, 6/7] media: mediatek: vcodec: prevent kernel crash when scp ipi timeout

["yunfei.dong@mediatek.com" <yunfei.dong@mediatek.com>]

Dear Hans,

Thanks for your review.
On Wed, 2022-05-18 at 11:37 +0200, Hans Verkuil wrote:
> Hi Yunfei,
> 
> On 5/13/22 11:25, Yunfei Dong wrote:
> > When SCP timeout during playing video, kernel crashes with
> > following
> > message. It's caused by accessing NULL pointer in
> > vpu_dec_ipi_handler.
> > This patch doesn't solve the root cause of NULL pointer, but merely
> > prevent kernel crashed when encounter the NULL pointer.
> 
> Is the root cause being addressed as well? Where is the root cause?
> Is it
> in this driver or in the scp (i.e. the remoteproc) driver?
> 
> I need a bit more information to decide whether this series is ready
> to
> be merged for 5.20 or not.
> 
> Regards,
> 
> 	Hans
> 
Vpu will be NUll when scp(micro processor) is hang or crash. Need to
keep kernel works well , so add this patch.

Best Regards,
Yunfei Dong
> > 
> > After applied this patch, kernel keeps alive, only the video player
> > turns
> > to green screen.
> > 
> > [67242.065474] pc : vpu_dec_ipi_handler+0xa0/0xb20 [mtk_vcodec_dec]
> > [67242.065485] [MTK_V4L2] level=0 fops_vcodec_open(),334:
> > 18000000.vcodec_dec decoder [135]
> > [67242.065523] lr : scp_ipi_handler+0x11c/0x244 [mtk_scp]
> > [67242.065540] sp : ffffffbb4207fb10
> > [67242.065557] x29: ffffffbb4207fb30 x28: ffffffd00a1d5000
> > [67242.065592] x27: 1ffffffa0143aa24 x26: 0000000000000000
> > [67242.065625] x25: dfffffd000000000 x24: ffffffd0168bfdb0
> > [67242.065659] x23: 1ffffff76840ff74 x22: ffffffbb41fa8a88
> > [67242.065692] x21: ffffffbb4207fb9c x20: ffffffbb4207fba0
> > [67242.065725] x19: ffffffbb4207fb98 x18: 0000000000000000
> > [67242.065758] x17: 0000000000000000 x16: ffffffd042022094
> > [67242.065791] x15: 1ffffff77ed4b71a x14: 1ffffff77ed4b719
> > [67242.065824] x13: 0000000000000000 x12: 0000000000000000
> > [67242.065857] x11: 0000000000000000 x10: dfffffd000000001
> > [67242.065890] x9 : 0000000000000000 x8 : 0000000000000002
> > [67242.065923] x7 : 0000000000000000 x6 : 000000000000003f
> > [67242.065956] x5 : 0000000000000040 x4 : ffffffffffffffe0
> > [67242.065989] x3 : ffffffd043b841b8 x2 : 0000000000000000
> > [67242.066021] x1 : 0000000000000010 x0 : 0000000000000010
> > [67242.066055] Call trace:
> > [67242.066092]  vpu_dec_ipi_handler+0xa0/0xb20 [mtk_vcodec_dec
> > 12220d230d83a7426fc38c56b3e7bc6066955bae]
> > [67242.066119]  scp_ipi_handler+0x11c/0x244 [mtk_scp
> > 8fb69c2ef141dd3192518b952b65aba35627b8bf]
> > [67242.066145]  mt8192_scp_irq_handler+0x70/0x128 [mtk_scp
> > 8fb69c2ef141dd3192518b952b65aba35627b8bf]
> > [67242.066172]  scp_irq_handler+0xa0/0x114 [mtk_scp
> > 8fb69c2ef141dd3192518b952b65aba35627b8bf]
> > [67242.066200]  irq_thread_fn+0x84/0xf8
> > [67242.066220]  irq_thread+0x170/0x1ec
> > [67242.066242]  kthread+0x2f8/0x3b8
> > [67242.066264]  ret_from_fork+0x10/0x30
> > [67242.066292] Code: 38f96908 35003628 91004340 d343fc08 (38f96908)
> > 
> > Signed-off-by: Tinghan Shen <tinghan.shen@mediatek.com>
> > Signed-off-by: Yunfei Dong <yunfei.dong@mediatek.com>
> > Reviewed-by: Macpaul Lin <macpaul.lin@mediatek.com>
> > ---
> >  drivers/media/platform/mediatek/vcodec/vdec_vpu_if.c | 5 +++++
> >  1 file changed, 5 insertions(+)
> > 
> > diff --git a/drivers/media/platform/mediatek/vcodec/vdec_vpu_if.c
> > b/drivers/media/platform/mediatek/vcodec/vdec_vpu_if.c
> > index 35f4d5583084..1041dd663e76 100644
> > --- a/drivers/media/platform/mediatek/vcodec/vdec_vpu_if.c
> > +++ b/drivers/media/platform/mediatek/vcodec/vdec_vpu_if.c
> > @@ -91,6 +91,11 @@ static void vpu_dec_ipi_handler(void *data,
> > unsigned int len, void *priv)
> >  	struct vdec_vpu_inst *vpu = (struct vdec_vpu_inst *)
> >  					(unsigned long)msg-
> > >ap_inst_addr;
> >  
> > +	if (!vpu) {
> > +		mtk_v4l2_err("ap_inst_addr is NULL");
> > +		return;
> > +	}
> > +
> >  	mtk_vcodec_debug(vpu, "+ id=%X", msg->msg_id);
> >  
> >  	vpu->failure = msg->status;