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

[Michal Simek <michal.simek@amd.com>]

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