* a problem about the function of acpi_ec_read_data
@ 2008-08-14 7:32 Zhao Yakui
2008-08-15 20:38 ` Alexey Starikovskiy
0 siblings, 1 reply; 3+ messages in thread
From: Zhao Yakui @ 2008-08-14 7:32 UTC (permalink / raw)
To: astarikovskiy; +Cc: linux-acpi, lenb
Hi, Alexey
There is a question about the function of acpi_ec_read_data.
When the data is ready for OS, OS will check the OBF flag of EC status and then call the following
function to read the data returned by EC controller.
static inline u8 acpi_ec_read_data(struct acpi_ec *ec)
{
u8 x = inb(ec->data_addr);
pr_debug(PREFIX "---> data = 0x%2.2x\n", x);
return inb(ec->data_addr);
}
Why is the EC data I/O address accessed twice to get the data returned by EC controller?
Does there exist some specific reason about it?
Thanks for the comments.
Best regards.
Yakui
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: a problem about the function of acpi_ec_read_data
2008-08-14 7:32 a problem about the function of acpi_ec_read_data Zhao Yakui
@ 2008-08-15 20:38 ` Alexey Starikovskiy
0 siblings, 0 replies; 3+ messages in thread
From: Alexey Starikovskiy @ 2008-08-15 20:38 UTC (permalink / raw)
To: Zhao Yakui; +Cc: linux-acpi, lenb
Hi Zhao,
Good catch, it is probably debug patch gone bad. it is definitely needs to read "return x;"
Please submit patch, I ACK it.
Thanks,
Alex.
Zhao Yakui wrote:
> Hi, Alexey
> There is a question about the function of acpi_ec_read_data.
>
> When the data is ready for OS, OS will check the OBF flag of EC status and then call the following
> function to read the data returned by EC controller.
>
> static inline u8 acpi_ec_read_data(struct acpi_ec *ec)
> {
> u8 x = inb(ec->data_addr);
> pr_debug(PREFIX "---> data = 0x%2.2x\n", x);
> return inb(ec->data_addr);
> }
>
> Why is the EC data I/O address accessed twice to get the data returned by EC controller?
> Does there exist some specific reason about it?
>
> Thanks for the comments.
>
> Best regards.
> Yakui
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* a problem about the function of acpi_ec_read_data
@ 2008-08-18 2:37 Zhao Yakui
0 siblings, 0 replies; 3+ messages in thread
From: Zhao Yakui @ 2008-08-18 2:37 UTC (permalink / raw)
To: astarikovskiy; +Cc: linux-acpi, lenb
Hi, Alexey
There is a question about the function of acpi_ec_read_data.
When the data is ready for OS, OS will check the OBF flag of EC status and then call the following
function to read the data returned by EC controller.
static inline u8 acpi_ec_read_data(struct acpi_ec *ec)
{
u8 x = inb(ec->data_addr);
pr_debug(PREFIX "---> data = 0x%2.2x\n", x);
return inb(ec->data_addr);
}
Why is the EC data I/O address accessed twice to get the data returned by EC controller?
Does there exist some specific reason about it?
Thanks for the comments.
Best regards.
Yakui
^ permalink raw reply [flat|nested] 3+ messages in thread
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