lkml.org 
[lkml]   [2021]   [Dec]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH v2 1/4] Docs: usb: update usb_bulk_msg receiving example
From
Date
On 12/5/21 12:00 PM, Greg KH wrote:
> On Sat, Dec 04, 2021 at 05:35:11PM +0100, Philipp Hortmann wrote:
>> Clarification that this example is not in the driver template anymore.
>> Update code example so that it fits best to usb-skeleton.c
>> Update format of function names
>>
>> Signed-off-by: Philipp Hortmann <philipp.g.hortmann@gmail.com>
>> ---
>> V1 -> V2: Added "Update format of function names" to patch description
>> Corrected format of function names like the following example:
>> "`usb_bulk_msg` function" to "usb_bulk_msg()"
>> ---
>> .../driver-api/usb/writing_usb_driver.rst | 32 +++++++++----------
>> 1 file changed, 16 insertions(+), 16 deletions(-)
>>
>> diff --git a/Documentation/driver-api/usb/writing_usb_driver.rst b/Documentation/driver-api/usb/writing_usb_driver.rst
>> index b43e1ce49f0e..ed11398837e5 100644
>> --- a/Documentation/driver-api/usb/writing_usb_driver.rst
>> +++ b/Documentation/driver-api/usb/writing_usb_driver.rst
>> @@ -218,36 +218,36 @@ do very much processing at that time. Our implementation of
>> ``skel_write_bulk_callback`` merely reports if the urb was completed
>> successfully or not and then returns.
>>
>> -The read function works a bit differently from the write function in
>> +This read function works a bit differently from the write function in
>> that we do not use an urb to transfer data from the device to the
>> -driver. Instead we call the :c:func:`usb_bulk_msg` function, which can be used
>> +driver. Instead we call usb_bulk_msg(), which can be used
>> to send or receive data from a device without having to create urbs and
>> -handle urb completion callback functions. We call the :c:func:`usb_bulk_msg`
>> -function, giving it a buffer into which to place any data received from
>> +handle urb completion callback functions. We call usb_bulk_msg(),
>> +giving it a buffer into which to place any data received from
>> the device and a timeout value. If the timeout period expires without
>> receiving any data from the device, the function will fail and return an
>> error message. This can be shown with the following code::
>>
>> /* do an immediate bulk read to get data from the device */
>> - retval = usb_bulk_msg (skel->dev,
>> - usb_rcvbulkpipe (skel->dev,
>> - skel->bulk_in_endpointAddr),
>> - skel->bulk_in_buffer,
>> - skel->bulk_in_size,
>> - &count, 5000);
>> + rv = usb_bulk_msg(dev->udev,
>
> Why are you changing the varible name? That seems unnecessary.
Reason is that retval does not exist in skel_read().
>
>> + usb_rcvbulkpipe (dev->udev,
>> + dev->bulk_in_endpointAddr),
>> + dev->bulk_in_buffer,
>> + dev->bulk_in_size,
>> + &len, 5000);
>> /* if the read was successful, copy the data to user space */
>> - if (!retval) {
>> - if (copy_to_user (buffer, skel->bulk_in_buffer, count))
>> - retval = -EFAULT;
>> + if (!rv) {
>> + if (copy_to_user (buffer, dev->bulk_in_buffer, len))
>> + rv = -EFAULT;
>> else
>> - retval = count;
>> + rv = len;
>> }
>
> Leaving the variable name alone keeps this patch much smaller.
Will leave the variable name in the next patch.
>
>>
>>
>> -The :c:func:`usb_bulk_msg` function can be very useful for doing single reads
>> +usb_bulk_msg() can be very useful for doing single reads
>
> You are doing different things in this patch, one is converting the
> function style and one is updating the text. How about doing just the
> function name stuff first, all in one patch, and then the updates, as
> that would make it much easier to read.
Will be changed.
>
> Also, any reason you aren't cc:ing the USB maintainer on these changes? :)
According to:
perl scripts/get_maintainer.pl --separator , --nokeywords --nogit
--nogit-fallback --norolestats -f
Documentation/driver-api/usb/writing_usb_driver.rst
Jonathan Corbet
<corbet@lwn.net>,linux-doc@vger.kernel.org,linux-kernel@vger.kernel.org
you are not in charge.
thanks,
Philipp Hortmann
> thanks,
>
> greg k-h
>

\
 
 \ /
  Last update: 2021-12-05 18:05    [W:0.052 / U:1.692 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site