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Date: Mon, 09 Mar 2009 12:35:33 +0800
From: gyang <graf.yang@...log.com>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: Bryan Wu <cooloney@...nel.org>, samuel@...tiz.org,
irda-users@...ts.sourceforge.net, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] [net/irda]: new Blackfin on-chip SIR IrDA driver
On Fri, 2009-03-06 at 14:58 -0800, Andrew Morton wrote:
> On Fri, 6 Mar 2009 14:44:45 +0800
> Bryan Wu <cooloney@...nel.org> wrote:
>
> > From: Graf Yang <graf.yang@...log.com>
> >
> > Signed-off-by: Graf Yang <graf.yang@...log.com>
> > Signed-off-by: Bryan Wu <cooloney@...nel.org>
>
> Mutter. Nothing to be said at all?
>
> > drivers/net/irda/bfin_sir.h | 147 ++++++++
> > 4 files changed, 989 insertions(+), 0 deletions(-)
> > create mode 100644 drivers/net/irda/bfin_sir.c
> > create mode 100644 drivers/net/irda/bfin_sir.h
> >
> > diff --git a/drivers/net/irda/Kconfig b/drivers/net/irda/Kconfig
> > index e631755..0e4d7e0 100644
> > --- a/drivers/net/irda/Kconfig
> > +++ b/drivers/net/irda/Kconfig
> > @@ -17,6 +17,51 @@ config IRTTY_SIR
> >
> > If unsure, say Y.
> >
> > +config BFIN_SIR
> > + tristate "Blackfin SIR on UART"
> > + depends on BLACKFIN && IRDA
> > + default n
> > + help
> > + Say Y here if your want to enable SIR function on Blackfin UART
> > + devices.
> > +
> > + To activate this driver you can start irattach like:
> > + "irattach irda0 -s"
> > +
> > + Saying M, it will be built as a module named bfin_sir.
> > +
> > + Note that you need to turn off one of the serial drivers for SIR
> > + to use that UART.
> > +
> > +config BFIN_SIR3
> > + bool "Blackfin SIR on UART3"
> > + depends on BFIN_SIR && !SERIAL_BFIN_UART3 && (BF54x)
> > +
> > +config BFIN_SIR1
> > + bool "Blackfin SIR on UART1"
> > + depends on BFIN_SIR && !SERIAL_BFIN_UART1 && (!BF531 && !BF532 && !BF533 && !BF561)
> > +
> > +config BFIN_SIR0
> > + bool "Blackfin SIR on UART0"
> > + depends on BFIN_SIR && !SERIAL_BFIN_UART0
> > +
> > +config BFIN_SIR2
> > + bool "Blackfin SIR on UART2"
> > + depends on BFIN_SIR && !SERIAL_BFIN_UART2 && (BF54x || BF538 || BF539)
> > +
> > +choice
> > + prompt "SIR Mode"
> > + depends on BFIN_SIR
> > + default SIR_BFIN_DMA
> > +
> > +config SIR_BFIN_DMA
> > + bool "DMA mode"
> > + depends on !DMA_UNCACHED_NONE
> > +
> > +config SIR_BFIN_PIO
> > + bool "PIO mode"
> > +endchoice
>
> This arrangement is pretty user-hostile. It requires that people
> reconfigure and rebuild their kernel any time they want to change the
> driver options.
>
> It would be much better to be able to do this via a kernel boot option.
>
> It would be better still to be able to do this via a module parameter.
>
> It would be better still to be able to do this via a runtime knob:
> ioctl, sysfs file, whatever.
>
> it would be better still to do all this automatically at probe time.
>
> What you've chosen here is the worst possible solution, sorry.
Because most of our end-users are using it in embedded devices, they
want the binary be smaller and faster. The compile time overhead is not
a problem.
>
> > comment "Dongle support"
> >
> > ...
> >
> > +static void turnaround_delay(unsigned long last_jif, int mtt)
> > +{
> > + long ticks;
> > +
> > + mtt = mtt < 10000 ? 10000 : mtt;
> > + ticks = 1 + mtt / (USEC_PER_SEC / HZ);
> > + schedule_timeout_interruptible(ticks);
> > +}
>
> If the calling task has signal_pending() then the
> schedule_timeout_interruptible() will return immediately. I bet this
> breaks the driver.
>
> Fixable by using schedule_timeout_uninterruptible().
OK, Thanks.
>
> >
> > ...
> >
> > +static void bfin_sir_stop_tx(struct bfin_sir_port *port)
> > +{
> > +#ifdef CONFIG_SIR_BFIN_DMA
> > + disable_dma(port->tx_dma_channel);
> > +#endif
> > +
> > + while (!(SIR_UART_GET_LSR(port) & THRE))
> > + continue;
>
> cpu_relax().
>
> > + SIR_UART_STOP_TX(port);
> > +}
> > +
> >
> > ...
> >
> > +#ifdef CONFIG_SIR_BFIN_PIO
> > +static void bfin_sir_tx_chars(struct net_device *dev)
> > +{
> > + unsigned int chr;
> > + struct bfin_sir_self *self = netdev_priv(dev);
> > + struct bfin_sir_port *port = self->sir_port;
> > +
> > + if (self->tx_buff.len != 0) {
> > + chr = *(self->tx_buff.data);
> > + SIR_UART_PUT_CHAR(port, chr);
> > + self->tx_buff.data++;
> > + self->tx_buff.len--;
>
> I don't see any locking which protects the tx_buff.
I will add lock for both tx/rx.
>
> > + } else {
> > + self->stats.tx_packets++;
> > + self->stats.tx_bytes += self->tx_buff.data - self->tx_buff.head;
> > + if (self->newspeed) {
> > + bfin_sir_set_speed(port, self->newspeed);
> > + self->speed = self->newspeed;
> > + self->newspeed = 0;
> > + }
> > + bfin_sir_stop_tx(port);
> > + bfin_sir_enable_rx(port);
> > + /* I'm hungry! */
> > + netif_wake_queue(dev);
> > + }
> > +}
> > +
> > +static void bfin_sir_rx_chars(struct net_device *dev)
> > +{
> > + struct bfin_sir_self *self = netdev_priv(dev);
> > + struct bfin_sir_port *port = self->sir_port;
> > + unsigned char ch;
> > +
> > + SIR_UART_CLEAR_LSR(port);
> > + ch = SIR_UART_GET_CHAR(port);
> > + async_unwrap_char(dev, &self->stats, &self->rx_buff, ch);
> > + dev->last_rx = jiffies;
> > +}
> > +
> > +static irqreturn_t bfin_sir_rx_int(int irq, void *dev_id)
> > +{
> > + struct net_device *dev = dev_id;
> > + struct bfin_sir_self *self = netdev_priv(dev);
> > + struct bfin_sir_port *port = self->sir_port;
>
> blank line here.
>
> > + while ((SIR_UART_GET_LSR(port) & DR))
> > + bfin_sir_rx_chars(dev);
> > +
> > + return IRQ_HANDLED;
> > +}
> > +
> >
> > ...
> >
> > +static irqreturn_t bfin_sir_dma_tx_int(int irq, void *dev_id)
> > +{
> > + struct net_device *dev = dev_id;
> > + struct bfin_sir_self *self = netdev_priv(dev);
> > + struct bfin_sir_port *port = self->sir_port;
> > + spin_lock(&self->lock);
>
> please prefer to put a blank line after end-of-locals and before
> start-of-code,
>
> > + if (!(get_dma_curr_irqstat(port->tx_dma_channel)&DMA_RUN)) {
> > + clear_dma_irqstat(port->tx_dma_channel);
> > + bfin_sir_stop_tx(port);
> > +
> > + self->stats.tx_packets++;
> > + self->stats.tx_bytes += self->tx_buff.len;
> > + self->tx_buff.len = 0;
> > + if (self->newspeed) {
> > + bfin_sir_set_speed(port, self->newspeed);
> > + self->speed = self->newspeed;
> > + self->newspeed = 0;
> > + }
> > + bfin_sir_enable_rx(port);
> > + /* I'm hungry! */
> > + netif_wake_queue(dev);
> > + port->tx_done = 1;
> > + }
> > + spin_unlock(&self->lock);
> > +
> > + return IRQ_HANDLED;
> > +}
> > +
> > +static void bfin_sir_dma_rx_chars(struct net_device *dev)
> > +{
> > + struct bfin_sir_self *self = netdev_priv(dev);
> > + struct bfin_sir_port *port = self->sir_port;
> > + int i;
> > +
>
> like that.
>
> > + SIR_UART_CLEAR_LSR(port);
> > +
> > + for (i = port->rx_dma_buf.head; i < port->rx_dma_buf.tail; i++)
> > + async_unwrap_char(dev, &self->stats, &self->rx_buff, port->rx_dma_buf.buf[i]);
> > +}
> > +
> >
> > ...
> >
> > +static int bfin_sir_stop(struct net_device *dev)
> > +{
> > + struct bfin_sir_self *self = netdev_priv(dev);
> > +
> > + flush_scheduled_work();
>
> flush_scheduled_work() flushes all work items. It is preferable to use
> flush_work() to flush a single item.
OK, thanks.
>
>
> > + bfin_sir_shutdown(self->sir_port, dev);
> > +
> > + if (self->rxskb) {
> > + dev_kfree_skb(self->rxskb);
> > + self->rxskb = NULL;
> > + }
> > +
> > + /* Stop IrLAP */
> > + if (self->irlap) {
> > + irlap_close(self->irlap);
> > + self->irlap = NULL;
> > + }
> > +
> > + netif_stop_queue(dev);
> > + self->open = 0;
> > +
> > + return 0;
> > +}
> > +
> > +static int bfin_sir_init_iobuf(iobuff_t *io, int size)
> > +{
> > + io->head = kmalloc(size, GFP_KERNEL | GFP_DMA);
>
> Does it actually _need_ the GFP_DMA?
>
> It is wrong (or at least, contradictory) to combine GFP_KERNEL and
> GFP_DMA together in this manner. Use one or the other.
OK. Thanks.
>
> > + if (!io->head)
> > + return -ENOMEM;
> > + io->truesize = size;
> > + io->in_frame = FALSE;
> > + io->state = OUTSIDE_FRAME;
> > + io->data = io->head;
> > + return 0;
> > +}
> > +
> >
> > ...
> >
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