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From: YongSu Yoo <yongsuyoo0215@gmail.com>
Date: Thu, 23 May 2024 22:16:15 +0900
Message-ID: <CANXPkT6GdjfmRr5rzJfqc0N1O2dAOneZKhLA4yCejGc3hV2kTA@mail.gmail.com>
Subject: Re: [PATCH] media: dvb_ca_en50221: Add a returing EBUSY logic into CA_RESET
To: mchehab@kernel.org, yongsuyoo0215@gmail.com, v4bel@theori.io, 
	linux-media@vger.kernel.org, linux-kernel@vger.kernel.org
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Dear All

Can you review this patch ?
Can you share how this modification is going ?

2024=EB=85=84 5=EC=9B=94 1=EC=9D=BC (=EC=88=98) =EC=98=A4=ED=9B=84 4:54, Yo=
ngSu Yoo <yongsuyoo0215@gmail.com>=EB=8B=98=EC=9D=B4 =EC=9E=91=EC=84=B1:
>
> Dear All
>
> Can you review this patch ?
> Can you share how this modification is going ?
>
> 2024=EB=85=84 4=EC=9B=94 11=EC=9D=BC (=EB=AA=A9) =EC=98=A4=ED=9B=84 9:02,=
 YongSu Yoo <yongsuyoo0215@gmail.com>=EB=8B=98=EC=9D=B4 =EC=9E=91=EC=84=B1:
> >
> > Dear All
> >
> > Can you review this patch ?
> > Can you share how this modification is going ?
> >
> > 2024=EB=85=84 3=EC=9B=94 8=EC=9D=BC (=EA=B8=88) =EC=98=A4=ED=9B=84 9:13=
, <yongsuyoo0215@gmail.com>=EB=8B=98=EC=9D=B4 =EC=9E=91=EC=84=B1:
> > >
> > > From: Yongsu yoo <yongsuyoo0215@gmail.com>
> > >
> > > Signed-off-by:Yongsu Yoo <yongsuyoo0215@gmail.com>
> > >
> > > In source/drivers/media/dvb-core/dvb_ca_en50221.c, if the CA_RESET io=
ctl
> > > is called, in a normal case, the state of the thread of the
> > > dvb_ca_en50221_thread_state_machine will transit like below order.
> > > DVB_CA_SLOTSTATE_NONE -> DVB_CA_SLOTSTATE_UNINITIALISED ->
> > > DVB_CA_SLOTSTATE_WAITREADY -> DVB_CA_SLOTSTATE_VALIDATE ->
> > > DVB_CA_SLOTSTATE_WAITFR -> DVB_CA_SLOTSTATE_LINKINIT ->
> > > DVB_CA_SLOTSTATE_RUNNING
> > > But in some problem cases, the state will become DVB_CA_SLOTSTATE_INV=
ALID.
> > > Among the above mentioned states, the DVB_CA_SLOTSTATE_NONE and
> > > the DVB_CA_SLOTSTATE_INVALID are "already stablized" states,
> > > whereas other states are "transiting" states.
> > > The "already stablized" states mean no matter how long time we wait,
> > > the state will not be changed.
> > > The "transiting" states mean the states whose final state is not yet
> > > determined. The state keeps to be changed. Only after some time passe=
s,
> > > we get to know whether the final state will be DVB_CA_SLOTSTATE_RUNNI=
NG
> > > or DVB_CA_SLOTSTATE_INVALID.
> > > During the "transiting" states, we do not yet know whether the
> > > CA_RESET operation, which triggered the "transiting" states, will
> > > succeed or fail. For this reason, during the "transiting" states, if
> > > another CA_RESET ioctl is called and if this new CA_RESET ioctl
> > > operation begins again, it will be meaningless and waste time.
> > > For preventing this problem from happening, we make CA_RESET ioctl do
> > > nothing and only return EBUSY if the ioctl is called during the
> > > "transiting" states.
> > > ---
> > >  drivers/media/dvb-core/dvb_ca_en50221.c | 8 +++++++-
> > >  1 file changed, 7 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/media/dvb-core/dvb_ca_en50221.c b/drivers/media/=
dvb-core/dvb_ca_en50221.c
> > > index baf64540dc00..2e8aec354b7c 100644
> > > --- a/drivers/media/dvb-core/dvb_ca_en50221.c
> > > +++ b/drivers/media/dvb-core/dvb_ca_en50221.c
> > > @@ -1362,13 +1362,19 @@ static int dvb_ca_en50221_io_do_ioctl(struct =
file *file,
> > >                         struct dvb_ca_slot *sl =3D &ca->slot_info[slo=
t];
> > >
> > >                         mutex_lock(&sl->slot_lock);
> > > -                       if (sl->slot_state !=3D DVB_CA_SLOTSTATE_NONE=
) {
> > > +                       if ((sl->slot_state =3D=3D DVB_CA_SLOTSTATE_R=
UNNING) ||
> > > +                           (sl->slot_state =3D=3D DVB_CA_SLOTSTATE_I=
NVALID)) {
> > >                                 dvb_ca_en50221_slot_shutdown(ca, slot=
);
> > >                                 if (ca->flags & DVB_CA_EN50221_FLAG_I=
RQ_CAMCHANGE)
> > >                                         dvb_ca_en50221_camchange_irq(=
ca->pub,
> > >                                                                      =
slot,
> > >                                                                      =
DVB_CA_EN50221_CAMCHANGE_INSERTED);
> > >                         }
> > > +                       else {
> > > +                               if (sl->slot_state !=3D DVB_CA_SLOTST=
ATE_NONE) {
> > > +                                       err =3D -EBUSY;
> > > +                               }
> > > +                       }
> > >                         mutex_unlock(&sl->slot_lock);
> > >                 }
> > >                 ca->next_read_slot =3D 0;
> > > --
> > > 2.17.1
> > >