speedtch usbatm.c,1.20,1.21 usbatm.h,1.13,1.14
rkagan at mail.ru
Wed Apr 27 00:42:07 EDT 2005
On Tue, Apr 26, 2005 at 11:39:02PM +0200, Duncan Sands wrote:
> Hi Roman, the channel initialization in usbatm_usb_probe seems messy.
Yes this is the part I'm the least happy myself.
> Near the start, you do:
> instance->rx_channel.endpoint = usb_rcvbulkpipe(usb_dev, driver->in);
> instance->tx_channel.endpoint = usb_sndbulkpipe(usb_dev, driver->out);
> instance->rx_channel.stride = ATM_CELL_SIZE + driver->rx_padding;
> instance->tx_channel.stride = ATM_CELL_SIZE + driver->tx_padding;
> instance->rx_channel.buf_size = rcv_buf_size * instance->rx_channel.stride;
> instance->tx_channel.buf_size = snd_buf_size * instance->tx_channel.stride;
> This is before calling bind. After bind you do:
> tasklet_init(&instance->rx_channel.tasklet, usbatm_rx_process, (unsigned long)instance);
> tasklet_init(&instance->tx_channel.tasklet, usbatm_tx_process, (unsigned long)instance);
> instance->rx_channel.usbatm = instance->tx_channel.usbatm = instance;
> Why do these in different places?
In some sense it's historical: this is where the corresponding bits were
initialized before. I think most of the before-bind stuff can safely go
One thing is special, however: the endpoints are initialized to bulk
pipes from usbatm_driver.in and .out, and I assumed that the subdriver
could override it by an iso pipe, if needed. I guess I should better
check the endpoint descriptor instead to determine if it's bulk or iso,
and this all can (and should) be done after bind.
> Also, you'd expect something called usbatm_init_channel
> to initialize the whole thing, but in fact it only initializes a bit of it (just as well,
> since otherwise it would wipe out the fields you already initialized). Why group this
> particular bit of initialization in a procedure, and not all, or other bits - what is the
I wouldn't call it "logic" - I just didn't think well about it :) At
some point I was scared that usbatm_init_channel() will turn into a
ten-argument function, most of which would be a simple assignment from
an argument to a field in the structure. That's certainly not true so
I'd better merge it into one function.
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