lkml.org 
[lkml]   [2020]   [Jul]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRe: [PATCH v4 09/10] powerpc/watchpoint: Return available watchpoints dynamically
Date
Ravi Bangoria <ravi.bangoria@linux.ibm.com> writes:
> On 7/20/20 9:12 AM, Jordan Niethe wrote:
>> On Fri, Jul 17, 2020 at 2:11 PM Ravi Bangoria
>> <ravi.bangoria@linux.ibm.com> wrote:
>>>
>>> So far Book3S Powerpc supported only one watchpoint. Power10 is
>>> introducing 2nd DAWR. Enable 2nd DAWR support for Power10.
>>> Availability of 2nd DAWR will depend on CPU_FTR_DAWR1.
>>>
>>> Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
>>> ---
>>> arch/powerpc/include/asm/cputable.h | 4 +++-
>>> arch/powerpc/include/asm/hw_breakpoint.h | 5 +++--
>>> 2 files changed, 6 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/arch/powerpc/include/asm/cputable.h b/arch/powerpc/include/asm/cputable.h
>>> index 3445c86e1f6f..36a0851a7a9b 100644
>>> --- a/arch/powerpc/include/asm/cputable.h
>>> +++ b/arch/powerpc/include/asm/cputable.h
>>> @@ -633,7 +633,9 @@ enum {
>>> * Maximum number of hw breakpoint supported on powerpc. Number of
>>> * breakpoints supported by actual hw might be less than this.
>>> */
>>> -#define HBP_NUM_MAX 1
>>> +#define HBP_NUM_MAX 2
>>> +#define HBP_NUM_ONE 1
>>> +#define HBP_NUM_TWO 2

>> I wonder if these defines are necessary - has it any advantage over
>> just using the literal?
>
> No, not really. Initially I had something like:
>
> #define HBP_NUM_MAX 2
> #define HBP_NUM_P8_P9 1
> #define HBP_NUM_P10 2
>
> But then I thought it's also not right. So I made it _ONE and _TWO.
> Now the function that decides nr watchpoints dynamically (nr_wp_slots)
> is in different file, I thought to keep it like this so it would be
> easier to figure out why _MAX is 2.

I don't think it makes anything clearer.

I had to stare at it thinking there was some sort of mapping or
indirection going on, before I realised it's just literally the number
of breakpoints.

So please just do:

static inline int nr_wp_slots(void)
{
return cpu_has_feature(CPU_FTR_DAWR1) ? 2 : 1;
}

If you think HBP_NUM_MAX needs explanation then do that with a comment,
it can refer to nr_wp_slots() if that's helpful.

cheers

\
 
 \ /
  Last update: 2020-07-21 13:37    [W:0.335 / U:0.752 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site