https://bugzilla.kernel.org/show_bug.cgi?id=209293
Bug ID: 209293
Summary: When I mask this bit, I'm still receiving input
characters, at least on a pl2303 USB UART. Looking at
the source code of drivers/usb/serial/, the *only*
driver appearing to respect CREAD is
digi_acceleport.c. All others seem to ignore it. To
the contra
Product: ACPI
Version: 2.5
Kernel Version: It seems that a lot of Linux kernel serial device
drivers are ignoring the CREAD
Hardware: All
OS: Linux
Tree: Mainline
Status: NEW
Severity: normal
Priority: P1
Component: ACPICA-Core
Assignee: [email protected]
Reporter: [email protected]
Regression: No
"Macro: tcflag_t CREAD - If this bit is set, input can be read from the
terminal. Otherwise, input is discarded when it arrives."
When I mask this bit, I'm still receiving input characters, at least on a
pl2303 USB UART. Looking at the source code of drivers/usb/serial/, the *only*
driver appearing to respect CREAD is digi_acceleport.c. All others seem to
ignore it. To the contrary, most drivers in drivers/tty/serial seem to
implement it.
In absence of low-level support in individual drivers to actually disable the
receiver in hardware, I would have at least expected the core tty/serial layer
to drop/discard any characters received by the hardware while CREAD is not set.
But that also doesn't appear to be the case.
What's even more worrying is that the tcsetattr() call succeeds, i.e. it is a
silent error. I would expect the kernel to either implement the functionalty
ino one way or another, or simply return tcsetattr() with an error if an
unsupported combination (i.e. CFLAG not set) is configured.
This is not a theoretical issue. Anyone implementing a half-duplex protocol
with shared Rx and Tx line will face the same issue.
https://sites.google.com/site/bestessaywritingservicereview/
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