linux-kernel - Re: [PATCH v7 16/19] staging: r8188eu: clean up rtw_read*() and rtw

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Date:   Sat, 18 Sep 2021 13:41:48 +0200
From:   "Fabio M. De Francesco" <fmdefrancesco@...il.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Larry Finger <Larry.Finger@...inger.net>,
        Phillip Potter <phil@...lpotter.co.uk>,
        Pavel Skripkin <paskripkin@...il.com>,
        linux-staging@...ts.linux.dev, linux-kernel@...r.kernel.org,
        David Laight <david.Laight@...lab.com>,
        Dan Carpenter <dan.carpenter@...cle.com>
Subject: Re: [PATCH v7 16/19] staging: r8188eu: clean up rtw_read*() and rtw_write*()

On Friday, September 17, 2021 4:45:29 PM CEST Greg Kroah-Hartman wrote:
> On Fri, Sep 17, 2021 at 09:18:34AM +0200, Fabio M. De Francesco wrote:
> > Clean up rtw_read{8,16,32}() and rtw_write{8,16,32,N}() in 
usb_ops_linux.c.
> > 
> > 1) Rename variables:
> >         length => len
> >         pio_priv => io_priv
> >         pintfhdl => intfhdl
> >         wvalue => address.
> 
> Wait, why are you changing wvalue?  Isn't that the USB name for this
> variable in the USB message sent to the device?  Check the USB spec
> before changing this, that is a common field and probably should not be
> changed.

Oh, sorry. This was due to my very limited knowledge of the USB subsystems 
and its Core API. So I misunderstood the semantics of this "wvalue" argument 
and we'll change it to "value" (just to remove that unnecessary 'w', that I 
guess is for "word"). 

I had thought that the mere knowledge of C and OS kernels (from a theoretical 
perspective) would suffice to work on the code that we change in our patches. 
Now I understand that such a naive approach is clearly wrong.

I have been too lazy to open your LDD 3rd ed. for reading but now I have 
decided that it is time to do it. Furthermore, I have found one more book 
about Linux device drivers and I'm about to read also its "Linux USB device 
drivers" chapter.

I think that by this evening I'll have some basic knowledge of the USB 
subsystem, at least of what is needed to avoid future mistakes like the one 
you noticed. :) 

Thank you very much for the time you spent reviewing our code and for taking 
the first 14 patches,

Fabio

> 
> thanks,
> 
> greg k-h