On 04 Σεπ 2006, at 8:28 ΜΜ, Sergei Shtylyov wrote:
Hello.
Russell King wrote:
BTW, can anybody enlighten me why 8250_au1x00.c came into
being at all?
Its only function seems to register the UART platform devices,
the thing
that is usually done in the board setup code, i. e. I'd rather
have it in arch/mips/au1000/common/platform.c (however, 8250.c
should have been able to filter out ports with UPIO_AU in case
CONFIG_SERIAL_8250_AU1X00 undefined)...
Seemed like a good idea at the moment to follow the already
existing convention.
Already existing convention is as per Sergei's mail actually - to
have the
platform device registration in arch/*. The others which you
thought were
convention there (accent, boca, fourport, hub6, mca) are all for
add-in
cards and aren't architecture specific.
Hence, they can't live in arch/*.
So yes, 8250_au1x00.c breaks the established convention because it
isn't
an add-in card.
Thanks for clarification.
Now another question to Pantelis: IIUC, the Alchemy UART
platform devices have UPF_SKIP_TEST set because of the Alchemy docs
claiming that UARTs other than UART3 don't have MCR/MSR and only
UART3 does have the full set of the modem control/status lines?
Were they indeed failing the loopback test for you? Asking because
on DBAu1550 board all (enabled) UARTs do pass the loopback test if
I get rid of this flag (however, Au1550 datasheet says MCR/MSR
exists on all UARTs, just no modem pins exist on UART0, and only
RTS-/CTS- pair on UART1 -- and the bits having no correspoding pins
seem to be tied high internally).
If I'm correct, the driver seems inconsistent in how it handles
UART_BUG_NOMSR flag, only checking it when deciding whether to
enable the modem status interrupts or not while actually it should
have been checked in serial8250_set_mctrl() and check_modem_status
() as well...
It also looks like the driver doesn't use Alchemy UARTs to their
full potential currently: UART3 has not only full set of modem
lines, but also is capable of the auto flow control (UART1 on
Au1550 also is). (Making use of these features howewer are
complicated by the auto flow control being only available in the
late steppings of Au1500 and UART3 modem pins being multiplexed
with GPIO...)
WBR, Sergei
PS: CCing linux-mips to keep people here informed. :-)
Hi Sergei,
Yes, 1550 has proper UARTs on all port, but not 1200 ;)
Somehow I thought that hacking 8250 to support two different Au's
(1550 & 1200)
wouldn't go down well; so I chickened out & settled for a subset that
would work on
both. Feel free to fight your way through to support all the
functionality you
require.
Pantelis
