Re: [PATCH RFC] staging: r8188eu: comment about the chip's packet format

[Larry Finger]

On 2/18/22 04:22, Dan Carpenter wrote:
> On Fri, Feb 18, 2022 at 10:22:53AM +0100, Martin Kaiser wrote:
> > The structs phy_rx_agc_info and phy_status_rpt define parts of the
> > header data that the r8188eu chipset sends to this driver via usb.
> >
> > Add a comment to clarify that we cannot modify the content of these
> > structures and remove seemingly unused fields.
> >
> > Signed-off-by: Martin Kaiser <martin@xxxxxxxxx>
> > ---
> >
> > Dear all,
> >
> > I experimented with "cleaning up" these structures and related code before
> > discovering that their content comes from usb packets we receive from the
> > r8188eu chipset.
> >
> > Would it make sense to add a word of warning to prevent others from
> > repeating this exercise?
>
> Just the fact that these structs are endian means they're from the
> firmware or the network.
>
> If a struct has a pointer in it, then it's rarely part of the UAPI but
> if it has endian data then it probably is.

Additionally, do not change any struct with the __packed attribute. Most will 
have endian variables as well, but not all will.

Testing after modifying any struct is a necessity.

Larry