Hi Andy,
On 30/07/2017 06:01, Andy Shevchenko wrote:
On Sun, Jul 30, 2017 at 6:19 AM, Paulo Alcantara <pcacjr@xxxxxxxxx> wrote:
The WMI queries are performed by evaluating the WMPV() method from ACPI
DSDT tables, and it takes three arguments: instance index, method id and
input data (buffer).
Currently the method id is hard-coded to 0x3 in hp_wmi_perform_query()
which means that it will perform WMI calls that expect an output data of
size 0x80 (128). The output size is usually OK for the WMI queries we
perform, however it would be better to pick the correct one before
evaluating the WMI method.
Which correct method id to choose can be figured out by looking at the
following ASL code from WVPI() method:
...
Name (PVSZ, Package (0x05)
{
Zero,
0x04,
0x80,
0x0400,
0x1000
})
Store (Zero, Local0)
If (LAnd (LGreaterEqual (Arg1, One), LLessEqual (Arg1, 0x05)))
{
Store (DerefOf (Index (PVSZ, Subtract (Arg1, One))), Local0)
}
...
Arg1 is the method id and PVSZ is the package used to index the
corresponding output size; 1 -> 0, 2 -> 4, 3 -> 128, 4 -> 1024, 5 ->
4096.
This patch maps the output size passed in hp_wmi_perform_query() to the
correct method id before evaluating the WMI method.
Thanks for the patch, my comments below.
+/* map output size to the corresponding WMI method id */
+static inline u32 outsize_to_mid(int outsize)
I would name it like
encode_outsize_for_pvsz
+{
+ if (!outsize)
+ return 1;
+ if (outsize <= 0x4)
+ return 2;
+ if (outsize <= 0x80)
+ return 3;
+ if (outsize <= 0x400)
+ return 4;
+ if (outsize <= 0x1000)
+ return 5;
+ return (u32)-1;
I would do other way around, i.e.
if (outsize > 4096)
return U32_MAX;
if (outsize > ...)
return ...;
if (outsize > 0)
return 2;
return 1;
Note two things:
1) use decimal integers for size (slightly better to read);
2) don't trick negative numbers.
+}
+ mid = outsize_to_mid(outsize);
+ if (WARN_ON(mid == (u32)-1))
And looking here, why you don't return int from that function directly
and use it's negative value as error code?
+ return -EINVAL;
+
Thanks for the quick review. I agree with all you comments and
suggestions. I'll send a v2 shortly.
-Paulo
