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| author |   Lukas Wunner <lukas@wunner.de> | 2021-12-28 18:22:00 +0100 |
|---|---|---|
| committer |   Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-12-30 13:23:44 +0100 |
| commit | b4a29b94804c4774f22555651296b838df6ec0e4 (patch) | |
| tree | 941ce02678fe2d72628c8bd9d4428b1ce100f985 /drivers/tty/serial/sunsu.c | |
| parent | serial: Fix incorrect rs485 polarity on uart open (diff) | |
| download | linux-dev-b4a29b94804c4774f22555651296b838df6ec0e4.tar.xz linux-dev-b4a29b94804c4774f22555651296b838df6ec0e4.zip | |
serial: 8250: Move Alpha-specific quirk out of the core
struct uart_8250_port contains mcr_mask and mcr_force members whose
sole purpose is to work around an Alpha-specific quirk. This code
doesn't belong in the core where it is executed by everyone else,
so move it to a proper ->set_mctrl callback which is used on the
affected Alpha machine only.
The quirk was introduced in January 1995:
https://git.kernel.org/pub/scm/linux/kernel/git/history/history.git/diff/drivers/char/serial.c?h=1.1.83
The members in struct uart_8250_port were added in 2002:
https://git.kernel.org/history/history/c/4524aad27854
The quirk applies to non-PCI Alphas and arch/alpha/Kconfig specifies
"select FORCE_PCI if !ALPHA_JENSEN". So apparently the only affected
machine is the EISA-based Jensen that Linus was working on back then:
https://lore.kernel.org/all/CAHk-=wj1JWZ3sCrGz16nxEj7=0O+srMg6Ah3iPTDXSPKEws_SA@mail.gmail.com/
Up until now the quirk is not applied unless CONFIG_PCI is disabled.
If users forget to do that or run a generic Alpha kernel, the serial
ports aren't usable on Jensen. Avoid by confining the quirk to
CONFIG_ALPHA_JENSEN instead of !CONFIG_PCI. On generic Alpha kernels,
auto-detect at runtime whether the quirk needs to be applied.
Cc: Russell King <rmk+kernel@armlinux.org.uk>
Cc: Ulrich Teichert <krypton@ulrich-teichert.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Link: https://lore.kernel.org/r/b83d069cb516549b8a5420e097bb6bdd806f36fc.1640695609.git.lukas@wunner.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty/serial/sunsu.c')
| -rw-r--r-- | drivers/tty/serial/sunsu.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/tty/serial/sunsu.c b/drivers/tty/serial/sunsu.c index 425a016f9db7..98b2f4fb9a99 100644 --- a/drivers/tty/serial/sunsu.c +++ b/drivers/tty/serial/sunsu.c @@ -127,7 +127,8 @@ static void serial_out(struct uart_sunsu_port *up, int offset, int value) * gate outputs a logical one. Since we use level triggered interrupts * we have lockup and watchdog reset. We cannot mask IRQ because * keyboard shares IRQ with us (Word has it as Bob Smelik's design). - * This problem is similar to what Alpha people suffer, see serial.c. + * This problem is similar to what Alpha people suffer, see + * 8250_alpha.c. */ if (offset == UART_MCR) value |= UART_MCR_OUT2; |