On Mon, 14.08.06 23:25, Yu, Luming (luming.yu@xxxxxxxxx) wrote:
Hi
> First of all, thanks for your patch.
You're welcome!
> >+static int acpi_ec_transaction(union acpi_ec *ec, u8 command,
> >+ const u8 *wdata, unsigned wdata_len,
> >+ u8 *rdata, unsigned rdata_len)
>
> I agree the name: transaction sounds better than read/write, and
> can reduce redundant code from separate read, write function.
> But, I guess using argument : u8 address will make the patch
> looks better.
I don't understand? You mean to add an additional parameter "u8
address" which would more or less be what wdata[0] is in my
suggestion?
This wouldn't work. Some of the EC commands do not take addresses as
arguments. In fact only "RD_EC" (read byte) and "WR_EC" (write byte)
take addresses. All others, BE_EC (burst enable), BD_EC (burst
disable) and QR_EC (query EC) do not take any argument at all.
Please note that ec_transaction() is *not* an API for reading/writing
a series of bytes from/to EC *memory*. Instead It is an API to write a
command to the EC control port and then read/write a series of bytes
from/to the EC data port.
The reason I did this patch was that I needed a generic way to access
the ACPI EC for my MSI S270 laptop driver. The non-standard EC MSI
builds into its laptops knows a few non-standard commands, besides the
standard commands listed above. These commands are not from the 0x80
range like RD/WR/BE/BD/QR, but from the 0x10 range. The data these
commands take is completely arbitrary, the commands have no notion of
an "address".
> >+{
> >+ if (acpi_ec_poll_mode)
> >+ return acpi_ec_poll_transaction(ec, command,
> >wdata, wdata_len, rdata, rdata_len);
> >+ else
> >+ return acpi_ec_intr_transaction(ec, command,
> >wdata, wdata_len, rdata, rdata_len);
> >+}
> >+
>
> It would be better to use a function pointer instead of
> using if-lese statement which looks not so neat.
Hmm, this is just the way the original acpi_ec_read()/acpi_ec_write()
functions worked. I didn't want to change too much of the logic,
because, honestly, I didn't understand everything in that source
file, such as the full semantics of the "poll" version of the
functions in contrast to the "intr" version.
> > static int acpi_ec_read(union acpi_ec *ec, u8 address, u32 * data)
> > {
> >- if (acpi_ec_poll_mode)
> >- return acpi_ec_poll_read(ec, address, data);
> >- else
> >- return acpi_ec_intr_read(ec, address, data);
> >+ int result;
> >+ u8 d;
> >+ result = acpi_ec_transaction(ec,
> >ACPI_EC_COMMAND_READ, &address, 1, &d, 1);
> >+ *data = d;
> >+ return result;
> > }
>
> Due to missing argument: address, you have to pass address in
> argument: wdata. This kind of code style is prone to error.
See above.
If we'd pass the address seperately we couldn't use
acpi_ec_transaction() to implement acpi_ec_query(), because QR_EC
doesn't take any address argument (wdata_len = 0).
> > static int acpi_ec_write(union acpi_ec *ec, u8 address, u8 data)
> > {
> >- if (acpi_ec_poll_mode)
> >- return acpi_ec_poll_write(ec, address, data);
> >- else
> >- return acpi_ec_intr_write(ec, address, data);
> >+ u8 wdata[2] = { address, data };
> >+ return acpi_ec_transaction(ec, ACPI_EC_COMMAND_WRITE,
> >wdata, 2, NULL, 0);
> > }
>
> It would be more clear if there is argument : address.
See above.
>
> >-static int acpi_ec_poll_read(union acpi_ec *ec, u8 address,
> >u32 * data)
> >+
> >+static int acpi_ec_poll_transaction(union acpi_ec *ec, u8 command,
> >+ const u8 *wdata, unsigned
> >wdata_len,
> >+ u8 *rdata, unsigned rdata_len)
> > {
> > acpi_status status = AE_OK;
> > int result = 0;
> > unsigned long flags = 0;
> > u32 glk = 0;
> >
> >- ACPI_FUNCTION_TRACE("acpi_ec_read");
> >+ ACPI_FUNCTION_TRACE("acpi_ec_poll_transaction");
> >
> >- if (!ec || !data)
> >+ if (!ec || !wdata || !wdata_len || (rdata_len && !rdata))
> > return_VALUE(-EINVAL);
>
>
> why return -EINVAL if wdata_len == 0?
Got me! This is a bug. This should read:
If (!ec || (wdata_len && !wdata) || (rdata_len && !rdata)) ...
BTW: I noticed that ec.c recieved quite a few cleanups in the
2.6.18-pre kernels. Apparently no logic really changed, but some
tracing has been removed among other minor stuff. My patch doesn't
apply cleanly anymore.
Shall I prepare an updated patch?
Thanks for reviewing,
Lennart
--
Lennart Poettering; lennart [at] poettering [dot] net
ICQ# 11060553; GPG 0x1A015CC4; http://0pointer.net/lennart/
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