On Wednesday, January 21, 2015 10:15:01 AM Jiang Liu wrote:
> On 2015/1/21 8:42, Rafael J. Wysocki wrote:
> > On Thursday, January 08, 2015 10:32:56 AM Jiang Liu wrote:
> >> According to ACPI spec 5, section 6.4.3.1 "24-Bit Memory Range Descriptor",
> >> minimum, maximum and address_length field in struct acpi_resource_memory24
> >> is in granularity of 256-bytes. So shift 8-bit left to get correct address.
> >
> > Are you sure about this?
> >
> > I'm reading ACPI 5.1 ATM and (on page 316) it only says about the range length
> > being in 256 byte blocks.
> Hi Rafael,
> According to ACPI spec 5.a sec 6.4.3.1,
> Byte 4, "Range minimum base address, _MIN, bits[7:0]", "Address
> bits[15:8] of the minimum base memory address for which
> the card may be configured."
> Byte 5, "Range minimum base address, _MIN, bits[15:8]", "Address
> bits[23:16] of the minimum base memory address for
> which the card may be configured".
Ah, OK.
So bits [15:0] of the _MIN field are bits [23:8] of the address. Tricky that.
I wonder why no problems with that have ever been reported ...
> Byte 10, "Range length, _LEN, bits[7:0]", "This field contains the lower
> eight bits of the memory range length. The range length provides the
> length of the memory range in 256 byte blocks."
> Byte 11, "Range length, _LEN, bits[15:8]", "This field contains the
> upper eight bits of the memory range length. The range length field
> provides the length of the memory range in 256 byte blocks."
>
> That means _MIN defines bits[23:8] of the minimal address, and _LEN
> is in granularity of 256 bytes, so shift them left by 8 bits.
> Regards,
> Gerry
>
> >
> >> Signed-off-by: Jiang Liu <jiang.liu@xxxxxxxxxxxxxxx>
> >> ---
> >> drivers/acpi/resource.c | 4 ++--
> >> 1 file changed, 2 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/drivers/acpi/resource.c b/drivers/acpi/resource.c
> >> index abe3a29ad802..f4aeef22a9d8 100644
> >> --- a/drivers/acpi/resource.c
> >> +++ b/drivers/acpi/resource.c
> >> @@ -90,8 +90,8 @@ bool acpi_dev_resource_memory(struct acpi_resource *ares, struct resource *res)
> >> switch (ares->type) {
> >> case ACPI_RESOURCE_TYPE_MEMORY24:
> >> memory24 = &ares->data.memory24;
> >> - acpi_dev_get_memresource(res, memory24->minimum,
> >> - memory24->address_length,
> >> + acpi_dev_get_memresource(res, memory24->minimum << 8,
> >> + memory24->address_length << 8,
> >> memory24->write_protect);
> >> break;
> >> case ACPI_RESOURCE_TYPE_MEMORY32:
> >>
> >
> --
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--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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