lkml.org 
[lkml]   [2008]   [Sep]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    From
    SubjectRe: [PATCH 03/18] lirc driver for 1st-gen Media Center Ed. USB IR transceivers
    Date
    On Tuesday 09 September 2008 21:21:40 Jonathan Corbet wrote:
    >
    > > + * 2003_11_11 - Restructured to minimalize code interpretation in
    > > the + * driver. The normal use case will be with lirc.
    > > + *
    > > + * 2004_01_01 - Removed all code interpretation. Generate mode2
    > > data + * for passing off to lirc. Cleanup
    > > + *
    > > + * 2004_01_04 - Removed devfs handle. Put in a temporary
    > > workaround + * for a known issue where repeats generate two
    > > + * sequential spaces (last_was_repeat_gap)
    > > + *
    > > + * 2004_02_17 - Changed top level api to no longer use fops, and
    > > + * instead use new interface for polling via
    > > + * lirc_thread. Restructure data read/mode2 generation to
    > > + * a single pass, reducing number of buffers. Rev to .2
    > > + *
    > > + * 2004_02_27 - Last of fixups to plugin->add_to_buf API. Properly
    > > + * handle broken fragments from the receiver. Up the
    > > + * sample rate and remove any pacing from
    > > + * fetch_more_data. Fixes all known issues.
    >
    > General convention is that this sort of changelog information belongs
    > in the SCM, not in the code. That's doubly true for the USB skeleton
    > driver info.

    I don't really care and I agree that the SCM is the preferred place for
    the information. The only problem is that the info is in a different
    SCM (lirc cvs repository).

    I've removed the changelogs from all files as long as no names wre
    mentioned.

    > > +#include <linux/smp_lock.h>
    >
    > It doesn't look like this include is needed.

    removed

    > > +/* Structure to hold all of our device specific stuff */
    > > +struct usb_skel {
    >
    > Perhaps renaming this structure to something more directly
    > descriptive would make sense?

    renamed to mceusb_device

    > > + struct usb_device *udev; /* save off the usb device pointer */
    > > + struct usb_interface *interface; /* the interface for this device
    > > */ + unsigned char minor; /* the starting minor number for this
    > > device */
    >
    > Minor numbers don't necessarily fit in an unsigned char.
    >
    > > + unsigned char num_ports; /* the number of ports this device has
    > > */ + char num_interrupt_in; /* number of interrupt in endpoints */
    > > + char num_bulk_in; /* number of bulk in endpoints */
    > > + char num_bulk_out; /* number of bulk out endpoints */
    > > +
    > > + unsigned char *bulk_in_buffer; /* the buffer to receive data */
    > > + int bulk_in_size; /* the size of the receive buffer */
    > > + __u8 bulk_in_endpointAddr; /* the address of bulk in endpoint */
    > > +
    > > + unsigned char *bulk_out_buffer; /* the buffer to send data */
    > > + int bulk_out_size; /* the size of the send buffer */
    > > + struct urb *write_urb; /* the urb used to send data */
    > > + __u8 bulk_out_endpointAddr; /* the address of bulk out endpoint
    > > */ +
    > > + atomic_t write_busy; /* true iff write urb is busy */
    > > + struct completion write_finished; /* wait for the write to finish
    > > */ +
    > > + wait_queue_head_t wait_q; /* for timeouts */
    > > + int open_count; /* number of times this port has been opened */
    > > + struct mutex sem; /* locks this structure */
    >
    > "sem" is not a semaphore; it should probably have a different name.

    renamed to lock

    > > +static void mceusb_setup(struct usb_device *udev)
    > > +{
    > > + char data[8];
    > > + int res;
    > > +
    > > + memset(data, 0, 8);
    > > +
    > > + /* Get Status */
    > > + res = usb_control_msg(udev, usb_rcvctrlpipe(udev, 0),
    > > + USB_REQ_GET_STATUS, USB_DIR_IN,
    > > + 0, 0, data, 2, HZ * 3);
    >
    > res is set many times in this function, but it is never checked. It
    > seems to me like the addition of some error handling would be a good
    > idea.

    sigh, It would be a good idea, not sure if I'm motivated enough to add
    that to a driver I can't test and I know almost nothing about.


    > > + /* These two are sent by the windows driver, but stall for
    > > + * me. I dont have an analyzer on the linux side so i can't
    > > + * see what is actually different and why the device takes
    > > + * issue with them
    > > + */
    >
    > Hmm...how was that information obtained? If this driver was
    > reverse-engineered, it would be good to know just what process was
    > followed.

    That's probably a question for the original author, Dan. CC added. I'm
    just cleaning them up for kernel inclusion.

    > > +static int msir_fetch_more_data(struct usb_skel *dev, int
    > > dont_block) +{
    >
    > ...
    >
    > > + /* retry a few times on overruns; map all
    > > + other errors to -EIO */
    > > + if (retval) {
    > > + if (retval == -EOVERFLOW && retries < 5) {
    > > + retries++;
    > > + interruptible_sleep_on_timeout(
    > > + &dev->wait_q, HZ);
    > > + continue;
    >
    > As others have noted, I think, getting new sleep_on() calls into the
    > kernel is kind of a hard sell.

    there are more, I'll fix them all before the next patchset get posted.

    > ...
    >
    > > +
    > > + /* select a "subminor" number (part of a minor number) */
    > > + down(&minor_table_mutex);
    >
    > So...this driver has a mutex called "sem" and a semaphore called
    > "minor_table_mutex". I suspect that minor_table_mutex should, in
    > fact, be a mutex.

    yes, the declaration looks like this:
    static DECLARE_MUTEX(...);

    which gives us a single holder semaphore. the static in front of
    DECLARE_MUTEX() fools checkpatch. changed to to DEFINE_MUTEX, also in
    two other drivers.

    >
    > ...
    >
    > > +error:
    > > + mceusb_delete(dev);
    > > + dev = NULL;
    > > + dprintk("%s: retval = %x", __func__, retval);
    > > + up(&minor_table_mutex);
    > > + return retval;
    > > +}
    >
    > This will leak the memory allocated for dev. It also leaves the
    > entry in minor_table pointing to a nonfunctional device.

    fixed.

    Thanks for the review.

    Janne



    \
     
     \ /
      Last update: 2008-09-10 02:01    [from the cache]
    ©2003-2011 Jasper Spaans