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Re: [PATCH] ACPI, APEI: Fixup incorrect 16-bit access width firmware bug

From Andy Shevchenko <andy.shevchenko@gmail.com>
Newsgroups linux.kernel
Subject Re: [PATCH] ACPI, APEI: Fixup incorrect 16-bit access width firmware bug
Date 2017-07-21 12:00 +0200
Message-ID <u5CT0-3b5-23@gated-at.bofh.it> (permalink)
References <u5CJj-37O-11@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On Fri, Jul 21, 2017 at 12:41 PM, Song liwei <liwei.song@windriver.com> wrote:

> [Firmware Bug]: APEI: Invalid bit width + offset in GAR [0xb2/16/0/1/1]
>
> This is due to an 8-bit access width is specified for a 16-bit register,
> Do bit_width check just like what the original commit have done.

>         else if (bit_width == 64 && bit_offset == 0 && (*paddr & 0x07) == 0 &&
>             *access_bit_width < 64)
>                 *access_bit_width = 64;
> +       else if (bit_width == 16 && bit_offset == 0 && (*paddr & 0x01) == 0 &&
> +           *access_bit_width < 16)
> +               *access_bit_width = 16;

Wouldn't be better to rearrange that it will go in a sequence
(16,32,64 or 64,32,16) ?

or move bit_offset == 0 into external condion

    /* Fixup common BIOS bug */
    if (bit_offset == 0) {
      if (bit_width == 16 && (*paddr & 0x01) == 0 && *access_bit_width < 16)
               *access_bit_width = 16;
      else if (bit_width == 32 && (*paddr & 0x03) == 0 &&
*access_bit_width < 32)
               *access_bit_width = 32;
      else if (bit_width == 64 && (*paddr & 0x07) == 0 &&
*access_bit_width < 64)
               *access_bit_width = 64;
    }


It might be (I'm not sure it will make it better, just a side note)
considered to convert each internal conditional to

...if (bit_width == XX && (*paddr & YY) == 0)
               *access_bit_width = max(*access_bit_width, bit_width);

-- 
With Best Regards,
Andy Shevchenko

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Thread

[PATCH] ACPI, APEI: Fixup incorrect 16-bit access width firmware bug Song liwei <liwei.song@windriver.com> - 2017-07-21 11:50 +0200
  Re: [PATCH] ACPI, APEI: Fixup incorrect 16-bit access width firmware bug Andy Shevchenko <andy.shevchenko@gmail.com> - 2017-07-21 12:00 +0200
    Re: [PATCH] ACPI, APEI: Fixup incorrect 16-bit access width firmware  bug Liwei Song <liwei.song@windriver.com> - 2017-07-26 08:20 +0200
      Re: [PATCH] ACPI, APEI: Fixup incorrect 16-bit access width firmware bug Andy Shevchenko <andy.shevchenko@gmail.com> - 2017-07-26 12:50 +0200

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