Re: [PATCH 2/3] net: emaclite: fix xemaclite_alignedread/write functions

[Jan Remes <jan.remes@codasip.com>]

On Mon, Aug 8, 2022 at 10:05 AM Michal Simek <michal.simek@amd.com> wrote:
>
>
>
> On 8/6/22 19:33, Ramon Fried wrote:
> > On Wed, Jul 13, 2022 at 5:02 PM Samuel Obuch <samuel.obuch@codasip.com> wrote:
> >>
> >> Use __raw_read* and __raw_write* functions to ensure read/write
> >> is passed to the memory-mapped regions, as non-volatile accesses
> >> may get optimised out.
> >>
> >> Signed-off-by: Samuel Obuch <samuel.obuch@codasip.com>
> >> ---
> >>   drivers/net/xilinx_emaclite.c | 9 ++++-----
> >>   1 file changed, 4 insertions(+), 5 deletions(-)
> >>
> >> diff --git a/drivers/net/xilinx_emaclite.c b/drivers/net/xilinx_emaclite.c
> >> index 5cd88e04fe..de7a2dee0b 100644
> >> --- a/drivers/net/xilinx_emaclite.c
> >> +++ b/drivers/net/xilinx_emaclite.c
> >> @@ -113,12 +113,12 @@ static void xemaclite_alignedread(u32 *srcptr, void *destptr, u32 bytecount)
> >>          /* Word aligned buffer, no correction needed. */
> >>          to32ptr = (u32 *) destptr;
> >>          while (bytecount > 3) {
> >> -               *to32ptr++ = *from32ptr++;
> >> +               *to32ptr++ = __raw_readl(from32ptr++);
> >>                  bytecount -= 4;
> >>          }
> >>          to8ptr = (u8 *) to32ptr;
> >>
> >> -       alignbuffer = *from32ptr++;
> >> +       alignbuffer = __raw_readl(from32ptr++);
> >>          from8ptr = (u8 *) &alignbuffer;
> >>
> >>          for (i = 0; i < bytecount; i++)
> >> @@ -136,8 +136,7 @@ static void xemaclite_alignedwrite(void *srcptr, u32 *destptr, u32 bytecount)
> >>
> >>          from32ptr = (u32 *) srcptr;
> >>          while (bytecount > 3) {
> >> -
> >> -               *to32ptr++ = *from32ptr++;
> >> +               __raw_writel(*from32ptr++, to32ptr++);
> >>                  bytecount -= 4;
> >>          }
> >>
> >> @@ -148,7 +147,7 @@ static void xemaclite_alignedwrite(void *srcptr, u32 *destptr, u32 bytecount)
> >>          for (i = 0; i < bytecount; i++)
> >>                  *to8ptr++ = *from8ptr++;
> >>
> >> -       *to32ptr++ = alignbuffer;
> >> +       __raw_writel(alignbuffer, to32ptr++);
> >>   }
> >>
> >>   static int wait_for_bit(const char *func, u32 *reg, const u32 mask,
> >> --
> >> 2.31.1
> >>
> > I think that using readl/writel is fine, no need for raw_...
>
> For microblaze that should be fine but let me ask my team to rest it on ARM.
> I think that __raw version are safer because this IP can also run on big endian
> systems and I think that was the reason why readl/writel wasn't used in past.
>
> Thanks,
> Michal

Hi Michal,

Do you have any new information on this? For the v2, it would be good
to have this resolved.

Thanks,
Jan