Am Freitag, den 18.12.2009, 07:00 -0500 schrieb Andy Walls:
> On Fri, 2009-12-18 at 08:14 -0200, Mauro Carvalho Chehab wrote:
> > Andy,
> >
> > Please review. The lack of porting cx23885 to new kfifo is stopping the merge
> > of the redesigned kfifo upstream.
>
>
> Stefani and Mauro,
>
> My comments/concerns are in line:
>
> > -------- Mensagem original --------
> > Assunto: [patch] media video cx23888 driver: ported to new kfifo API
> > Data: Fri, 18 Dec 2009 09:12:34 +0100
> > De: Stefani Seibold <stefani@xxxxxxxxxxx>
> > Para: linux-kernel@xxxxxxxxxxxxxxx, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>, Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxx>
> >
> > This patch will fix the cx23888 driver to use the new kfifo API.
> >
> > The patch-set is against current mm tree from 11-Dec-2009
> >
> > Greetings,
> > Stefani
> >
> > Signed-off-by: Stefani Seibold <stefani@xxxxxxxxxxx>
> > ---
> > cx23888-ir.c | 35 ++++++++++-------------------------
> > 1 file changed, 10 insertions(+), 25 deletions(-)
> >
> > --- mmotm.orig/drivers/media/video/cx23885/cx23888-ir.c 2009-12-18 08:42:53.936778002 +0100
> > +++ mmotm/drivers/media/video/cx23885/cx23888-ir.c 2009-12-18 09:03:04.808703259 +0100
> > @@ -124,15 +124,12 @@ struct cx23888_ir_state {
> > atomic_t rxclk_divider;
> > atomic_t rx_invert;
> >
> > - struct kfifo *rx_kfifo;
> > + struct kfifo rx_kfifo;
> > spinlock_t rx_kfifo_lock;
> >
> > struct v4l2_subdev_ir_parameters tx_params;
> > struct mutex tx_params_lock;
> > atomic_t txclk_divider;
> > -
> > - struct kfifo *tx_kfifo;
> > - spinlock_t tx_kfifo_lock;
> > };
> >
> > static inline struct cx23888_ir_state *to_state(struct v4l2_subdev *sd)
> > @@ -594,8 +591,9 @@ static int cx23888_ir_irq_handler(struct
> > if (i == 0)
> > break;
> > j = i * sizeof(u32);
> > - k = kfifo_put(state->rx_kfifo,
> > - (unsigned char *) rx_data, j);
> > + k = kfifo_in_locked(&state->rx_kfifo,
> > + (unsigned char *) rx_data, j,
> > + &state->rx_kfifo_lock);
> > if (k != j)
> > kror++; /* rx_kfifo over run */
> > }
> > @@ -631,7 +629,7 @@ static int cx23888_ir_irq_handler(struct
> > cx23888_ir_write4(dev, CX23888_IR_CNTRL_REG, cntrl);
> > *handled = true;
> > }
> > - if (kfifo_len(state->rx_kfifo) >= CX23888_IR_RX_KFIFO_SIZE / 2)
> > + if (kfifo_len(&state->rx_kfifo) >= CX23888_IR_RX_KFIFO_SIZE / 2)
> > events |= V4L2_SUBDEV_IR_RX_FIFO_SERVICE_REQ;
> >
> > if (events)
>
> I am concerned about reading the kfifo_len() without taking the lock,
> since another thread on another CPU may be reading from the kfifo at the
> same time.
>
> If the new kfifo implementation has an atomic_read() or something behind
> the kfifo_len() call, then OK.
>
>
> > @@ -657,7 +655,7 @@ static int cx23888_ir_rx_read(struct v4l
> > return 0;
> > }
> >
> > - n = kfifo_get(state->rx_kfifo, buf, n);
> > + n = kfifo_out_locked(&state->rx_kfifo, buf, n, &state->rx_kfifo_lock);
> >
> > n /= sizeof(u32);
> > *num = n * sizeof(u32);
> > @@ -785,7 +783,7 @@ static int cx23888_ir_rx_s_parameters(st
> > o->interrupt_enable = p->interrupt_enable;
> > o->enable = p->enable;
> > if (p->enable) {
> > - kfifo_reset(state->rx_kfifo);
> > + kfifo_reset(&state->rx_kfifo);
> > if (p->interrupt_enable)
> > irqenable_rx(dev, IRQEN_RSE | IRQEN_RTE | IRQEN_ROE);
> > control_rx_enable(dev, p->enable);
>
> Same concern about kfifo_reset() not taking the lock, and another thread
> reading data from the kfifo at the same time. In the cx23885 module,
> this would mostly likely happen only during module unload as things are
> being shut down.
>
>
> > @@ -892,7 +890,6 @@ static int cx23888_ir_tx_s_parameters(st
> > o->interrupt_enable = p->interrupt_enable;
> > o->enable = p->enable;
> > if (p->enable) {
> > - kfifo_reset(state->tx_kfifo);
> > if (p->interrupt_enable)
> > irqenable_tx(dev, IRQEN_TSE);
> > control_tx_enable(dev, p->enable);
>
> I don't mind the currently unused tx_kfifo being removed from the
> current implementation. However, could you leave a comment at this line
> about reseting a tx_kfifo? Otherwise, I may forget this one when I go
> to implement transmit.
>
>
> > @@ -1168,19 +1165,9 @@ int cx23888_ir_probe(struct cx23885_dev
> > return -ENOMEM;
> >
> > spin_lock_init(&state->rx_kfifo_lock);
> > - state->rx_kfifo = kfifo_alloc(CX23888_IR_RX_KFIFO_SIZE, GFP_KERNEL,
> > - &state->rx_kfifo_lock);
> > - if (state->rx_kfifo == NULL)
> > + if (kfifo_alloc(&state->rx_kfifo, CX23888_IR_RX_KFIFO_SIZE, GFP_KERNEL))
> > return -ENOMEM;
> >
> > - spin_lock_init(&state->tx_kfifo_lock);
> > - state->tx_kfifo = kfifo_alloc(CX23888_IR_TX_KFIFO_SIZE, GFP_KERNEL,
> > - &state->tx_kfifo_lock);
> > - if (state->tx_kfifo == NULL) {
> > - kfifo_free(state->rx_kfifo);
> > - return -ENOMEM;
> > - }
> > -
> > state->dev = dev;
> > state->id = V4L2_IDENT_CX23888_IR;
> > state->rev = 0;
> > @@ -1211,8 +1198,7 @@ int cx23888_ir_probe(struct cx23885_dev
> > sizeof(struct v4l2_subdev_ir_parameters));
> > v4l2_subdev_call(sd, ir, tx_s_parameters, &default_params);
> > } else {
> > - kfifo_free(state->rx_kfifo);
> > - kfifo_free(state->tx_kfifo);
> > + kfifo_free(&state->rx_kfifo);
> > }
> > return ret;
> > }
> > @@ -1231,8 +1217,7 @@ int cx23888_ir_remove(struct cx23885_dev
> >
> > state = to_state(sd);
> > v4l2_device_unregister_subdev(sd);
> > - kfifo_free(state->rx_kfifo);
> > - kfifo_free(state->tx_kfifo);
> > + kfifo_free(&state->rx_kfifo);
> > kfree(state);
> > /* Nothing more to free() as state held the actual v4l2_subdev object */
> > return 0;
> >
> >
>
>
> That's it. Thanks for taking the time to work up a patch.
Sorry, i ported it only to the new API. I did not touch the
functionality. Feel free to fix it and post it.
Stefani
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