Re: [PATCH] staging: r8188eu: Used u16 instead of __le16 in rtl8188e_set_FwMediaStatus_cmd()

[Gaurav Pathak <gauravpathak129@gmail.com>]

Thanks Dan and Larry for looking into it.
I also don't have much understanding of the underlying hardware, please do let me know
of your tests on big-endin machine.

> On little-endian systems, both are no-ops, thus it does not matter
Does it mean that the patch is not required and the original implementation
is okay?

On Tue, Jan 10, 2023 at 11:00:35AM -0600, Larry Finger wrote:
> On 1/10/23 08:17, Dan Carpenter wrote:
> > On Tue, Jan 10, 2023 at 07:20:58PM +0530, Gaurav Pathak wrote:
> > > - Changed 2nd argument from __le16 to u16 to fix sparse warning
> > >    "warning: incorrect type in argument 2 (different base types)"
> > > - Removed le16_to_cpu() in staging/r8188eu/hal/rtl8188e_cmd.c
> > > 
> > > Signed-off-by: Gaurav Pathak <gauravpathak129@gmail.com>
> > > ---
> > >   drivers/staging/r8188eu/hal/rtl8188e_cmd.c     | 4 ++--
> > >   drivers/staging/r8188eu/include/rtl8188e_cmd.h | 2 +-
> > >   2 files changed, 3 insertions(+), 3 deletions(-)
> > > 
> > > diff --git a/drivers/staging/r8188eu/hal/rtl8188e_cmd.c b/drivers/staging/r8188eu/hal/rtl8188e_cmd.c
> > > index 8310d7f53982..a055e71d30ae 100644
> > > --- a/drivers/staging/r8188eu/hal/rtl8188e_cmd.c
> > > +++ b/drivers/staging/r8188eu/hal/rtl8188e_cmd.c
> > > @@ -193,9 +193,9 @@ void rtl8188e_set_FwPwrMode_cmd(struct adapter *adapt, u8 Mode)
> > >   }
> > > -void rtl8188e_set_FwMediaStatus_cmd(struct adapter *adapt, __le16 mstatus_rpt)
> > > +void rtl8188e_set_FwMediaStatus_cmd(struct adapter *adapt, u16 mstatus_rpt)
> > >   {
> > > -	u16 mst_rpt = le16_to_cpu(mstatus_rpt);
> > > +	u16 mst_rpt = mstatus_rpt;
> > 
> > You are changing the behavior of the code here for big endian systems.
> > Either the change is good or bad.  TLDR; I suspect the change is bad but
> > I don't know.
> > 
> > The mstatus_rpt is CPU endian.  It is the one of two things for connect
> > or disconnect:
> > 
> >     connect: (psta->mac_id << 8) | 1
> > disconnect: (psta->mac_id << 8) | 0
> > 
> > So the question is in FillH2CCmd_88E() should the connect/disconnect
> > come before the mac_id as it currently does or should it only work that
> > way on little endian systems and be reversed on big endian systems?
> > My feeling is that the second option makes no sense so this patch is not
> > correct.
> > 
> > Instead what should happen is:
> > 
> > -void rtl8188e_set_FwMediaStatus_cmd(struct adapter *adapt, __le16 mstatus_rpt)
> > +void rtl8188e_set_FwMediaStatus_cmd(struct adapter *adapt, u16 mstatus_rpt)
> >   {
> > -	u16 mst_rpt = le16_to_cpu(mstatus_rpt);
> > +	__le16 mst_rpt = cpu_to_le16(mstatus_rpt);
> > 
> > But this is just my intuition and I don't know this hardware.
> 
> I agree with Dan. This patch was attacking the symptom, not the cause. The
> original Realtek driver confuses cpu_to_le16() with le16_to_cpu() in many
> places. Apparently, I missed this one. On little-endian systems, both are
> no-ops, thus it does not matter.
> 
> I have a big-endian system (PowerBook G4) and will test later today.
> 
> Larry
> 
>