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Re: [PATCH v5 3/6] iomap: introduce io{read|write}64_{lo_hi|hi_lo}

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On 30/07/17 10:03 AM, Andy Shevchenko wrote:
> On Thu, Jul 27, 2017 at 2:19 AM, Logan Gunthorpe <logang@deltatee.com> wrote:
>> In order to provide non-atomic functions for io{read|write}64 that will
>> use readq and writeq when appropriate. We define a number of variants
>> of these functions in the generic iomap that will do non-atomic
>> operations on pio but atomic operations on mmio.
>>
>> These functions are only defined if readq and writeq are defined. If
>> they are not, then the wrappers that always use non-atomic operations
>> from include/linux/io-64-nonatomic*.h will be used.
> 
> Don't you see here a slight problem?
> 
> In some cases we want to substitute atomic in favour of non-atomic
> when both are defined.
> So, please don't do this "smartly".

I'm not sure what you mean here. The driver should use ioread64 and
include an io-64-nonatomic header. Then there are three cases:

1) The arch has no atomic 64 bit io operations defined. In this case it
uses the non-atomic inline function in the io-64-nonatomic header.

2) The arch uses CONFIG_GENERIC_IOMAP and has readq defined, but not
ioread64 defined (likely because pio can't do atomic 64 bit operations
but mmio can). In this case we need to use the ioread64_xx functions
defined in iomap.c which do atomic mmio and non-atomic pio.

3) The arch has ioread64 defined so the atomic operation is used.

>> +u64 ioread64_lo_hi(void __iomem *addr)
>> +{
>> +       IO_COND(addr, return pio_read64_lo_hi(port), return readq(addr));
>> +       return 0xffffffffffffffffLL;
>> +}
> 
> U missed u.

I'll fix this in the next revision.

Thanks,

Logan

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[PATCH v5 0/6] make io{read|write}64 globally usable Logan Gunthorpe <logang@deltatee.com> - 2017-07-27 01:20 +0200
  [PATCH v5 1/6] powerpc: io.h: move iomap.h include so that it can use readq/writeq defs Logan Gunthorpe <logang@deltatee.com> - 2017-07-27 01:20 +0200
  [PATCH v5 2/6] powerpc: iomap.c: introduce io{read|write}64_{lo_hi|hi_lo} Logan Gunthorpe <logang@deltatee.com> - 2017-07-27 01:30 +0200
  [PATCH v5 5/6] ntb: ntb_hw_intel: use io-64-nonatomic instead of in-driver hacks Logan Gunthorpe <logang@deltatee.com> - 2017-07-27 01:30 +0200
    Re: [PATCH v5 5/6] ntb: ntb_hw_intel: use io-64-nonatomic instead of  in-driver hacks Jon Mason <jdmason@kudzu.us> - 2017-08-01 19:50 +0200
  [PATCH v5 3/6] iomap: introduce io{read|write}64_{lo_hi|hi_lo} Logan Gunthorpe <logang@deltatee.com> - 2017-07-27 01:30 +0200
    Re: [PATCH v5 3/6] iomap: introduce io{read|write}64_{lo_hi|hi_lo} Andy Shevchenko <andy.shevchenko@gmail.com> - 2017-07-30 18:10 +0200
      Re: [PATCH v5 3/6] iomap: introduce io{read|write}64_{lo_hi|hi_lo} Logan Gunthorpe <logang@deltatee.com> - 2017-07-31 18:00 +0200
        Re: [PATCH v5 3/6] iomap: introduce io{read|write}64_{lo_hi|hi_lo} Andy Shevchenko <andy.shevchenko@gmail.com> - 2017-07-31 18:20 +0200
          Re: [PATCH v5 3/6] iomap: introduce io{read|write}64_{lo_hi|hi_lo} Logan Gunthorpe <logang@deltatee.com> - 2017-07-31 18:40 +0200
            Re: [PATCH v5 3/6] iomap: introduce io{read|write}64_{lo_hi|hi_lo} Andy Shevchenko <andy.shevchenko@gmail.com> - 2017-07-31 20:00 +0200
              Re: [PATCH v5 3/6] iomap: introduce io{read|write}64_{lo_hi|hi_lo} Logan Gunthorpe <logang@deltatee.com> - 2017-07-31 20:10 +0200
                Re: [PATCH v5 3/6] iomap: introduce io{read|write}64_{lo_hi|hi_lo} Logan Gunthorpe <logang@deltatee.com> - 2017-07-31 20:10 +0200
                Re: [PATCH v5 3/6] iomap: introduce io{read|write}64_{lo_hi|hi_lo} Andy Shevchenko <andy.shevchenko@gmail.com> - 2017-07-31 20:20 +0200
                Re: [PATCH v5 3/6] iomap: introduce io{read|write}64_{lo_hi|hi_lo} Andy Shevchenko <andy.shevchenko@gmail.com> - 2017-07-31 20:10 +0200
  [PATCH v5 4/6] io-64-nonatomic: add io{read|write}64[be]{_lo_hi|_hi_lo} macros Logan Gunthorpe <logang@deltatee.com> - 2017-07-27 01:30 +0200
  [PATCH v5 6/6] crypto: caam: cleanup CONFIG_64BIT ifdefs when using io{read|write}64 Logan Gunthorpe <logang@deltatee.com> - 2017-07-27 01:30 +0200
  Re: [PATCH v5 0/6] make io{read|write}64 globally usable Horia Geantă <horia.geanta@nxp.com> - 2017-07-31 12:30 +0200

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