From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752705AbYIIX7q (ORCPT ); Tue, 9 Sep 2008 19:59:46 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750835AbYIIX7h (ORCPT ); Tue, 9 Sep 2008 19:59:37 -0400 Received: from scing.com ([217.160.110.58]:45476 "EHLO scing.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750823AbYIIX7h (ORCPT ); Tue, 9 Sep 2008 19:59:37 -0400 X-GoodMailTo: skipped X-GoodMailTo: skipped X-GoodMailTo: skipped X-GoodMailTo: skipped X-GoodMailTo: skipped From: Janne Grunau To: Jonathan Corbet Subject: Re: [PATCH 03/18] lirc driver for 1st-gen Media Center Ed. USB IR transceivers Date: Wed, 10 Sep 2008 01:59:32 +0200 User-Agent: KMail/1.9.9 Cc: Jarod Wilson , linux-kernel@vger.kernel.org, Christoph Bartelmus , dconti@acm.wwu.edu References: <1220933164-10160-1-git-send-email-jwilson@redhat.com> <1220933164-10160-4-git-send-email-jwilson@redhat.com> <20080909132140.3c0adcca@bike.lwn.net> In-Reply-To: <20080909132140.3c0adcca@bike.lwn.net> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200809100159.32524.j@jannau.net> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 > > 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