[aspeed][Nexthop] Enable UDMA on the AST2700 BMC uart12 console - #614
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[aspeed][Nexthop] Enable UDMA on the AST2700 BMC uart12 console#614jack-nexthop wants to merge 1 commit into
jack-nexthop wants to merge 1 commit into
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Enable dma-mode on uart12 in the NextHop B27 R0 device tree and add
fixes to make the UDMA console usable:
-`serial-8250_aspeed-fix-UDMA-ring-pointer-desync.patch`:
Keep driver's xmit kfifo and RX ring indices aligned with the
UDMA engine's ring pointers (software readonly, preserved
across channel reset) across `flush_buffer`, `set_termios`
and `open`. Without this the console hangs in `tcsetattr()`
on the second and later logins and wedges `RX` on the
first `termios` change (bricking console until
`serial-getty@ttyS12.service` is restarted)
-`soc-aspeed-udma-lower-idle-timeout.patch`
Lower `UDMA_TMOUT` from `0x200` (`~98.5`ms on AST2700) to `0x40`
(`~12` ms) so single keystrokes on a UDMA console are less visibly
delayed
Verified on NextHop B27 R0 (AST2700) hardware
Signed-off-by: Jack Cai <jack@nexthop.ai>
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paulmenzel
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Aug 22, 2026
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In the commit message, please don’t indent Verified on NextHop B27 R0 (AST2700) hardware.
Also, for people not knowing ASPEED code, on what repository are your patches based, and what is the plan to upstream them?
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Enable dma-mode on uart12 in the NextHop B27 R0 device tree and add fixes to make the UDMA console usable:
-
serial-8250_aspeed-fix-UDMA-ring-pointer-desync.patch:Keep driver's xmit kfifo and RX ring indices aligned with the
UDMA engine's ring pointers (software readonly, preserved
across channel reset) across
flush_buffer,set_termiosand
open. Without this the console hangs intcsetattr()on the second and later logins and wedges
RXon thefirst
termioschange (bricking console untilserial-getty@ttyS12.serviceis restarted)-
soc-aspeed-udma-lower-idle-timeout.patchLower
UDMA_TMOUTfrom0x200(~98.5ms on AST2700) to0x40(~12ms)so single keystrokes on a UDMA console are less visibly delayed
Verified on NextHop B27 R0 (AST2700) hardware