kernel/linux.git/include/linux/serial_core.h, branch v5.10.185

serial: 8250: Let drivers request full 16550A feature probing

2022-11-10T17:14:14+00:00

[ Upstream commit 9906890c89e4dbd900ed87ad3040080339a7f411 ] A SERIAL_8250_16550A_VARIANTS configuration option has been recently defined that lets one request the 8250 driver not to probe for 16550A device features so as to reduce the driver's device startup time in virtual machines. Some actual hardware devices require these features to have been fully determined however for their driver to work correctly, so define a flag to let drivers request full 16550A feature probing on a device-by-device basis if required regardless of the SERIAL_8250_16550A_VARIANTS option setting chosen. Fixes: dc56ecb81a0a ("serial: 8250: Support disabling mdelay-filled probes of 16550A variants") Cc: stable@vger.kernel.org # v5.6+ Reported-by: Anders Blomdell Signed-off-by: Maciej W. Rozycki Link: https://lore.kernel.org/r/alpine.DEB.2.21.2209202357520.41633@angie.orcam.me.uk Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin

serial: Create uart_xmit_advance()

2022-09-28T09:10:37+00:00

commit e77cab77f2cb3a1ca2ba8df4af45bb35617ac16d upstream. A very common pattern in the drivers is to advance xmit tail index and do bookkeeping of Tx'ed characters. Create uart_xmit_advance() to handle it. Reviewed-by: Andy Shevchenko Cc: stable Signed-off-by: Ilpo Järvinen Link: https://lore.kernel.org/r/20220901143934.8850-2-ilpo.jarvinen@linux.intel.com Signed-off-by: Greg Kroah-Hartman

serial: 8250: Fix PM usage_count for console handover

2022-07-21T19:20:19+00:00

commit f9b11229b79c0fb2100b5bb4628a101b1d37fbf6 upstream. When console is enabled, univ8250_console_setup() calls serial8250_console_setup() before .dev is set to uart_port. Therefore, it will not call pm_runtime_get_sync(). Later, when the actual driver is going to take over univ8250_console_exit() is called. As .dev is already set, serial8250_console_exit() makes pm_runtime_put_sync() call with usage count being zero triggering PM usage count warning (extra debug for univ8250_console_setup(), univ8250_console_exit(), and serial8250_register_ports()): [ 0.068987] univ8250_console_setup ttyS0 nodev [ 0.499670] printk: console [ttyS0] enabled [ 0.717955] printk: console [ttyS0] printing thread started [ 1.960163] serial8250_register_ports assigned dev for ttyS0 [ 1.976830] printk: console [ttyS0] disabled [ 1.976888] printk: console [ttyS0] printing thread stopped [ 1.977073] univ8250_console_exit ttyS0 usage:0 [ 1.977075] serial8250 serial8250: Runtime PM usage count underflow! [ 1.977429] dw-apb-uart.6: ttyS0 at MMIO 0x4010006000 (irq = 33, base_baud = 115200) is a 16550A [ 1.977812] univ8250_console_setup ttyS0 usage:2 [ 1.978167] printk: console [ttyS0] printing thread started [ 1.978203] printk: console [ttyS0] enabled To fix the issue, call pm_runtime_get_sync() in serial8250_register_ports() as soon as .dev is set for an uart_port if it has console enabled. This problem became apparent only recently because 82586a721595 ("PM: runtime: Avoid device usage count underflows") added the warning printout. I confirmed this problem also occurs with v5.18 (w/o the warning printout, obviously). Fixes: bedb404e91bb ("serial: 8250_port: Don't use power management for kernel console") Cc: stable Tested-by: Tony Lindgren Reviewed-by: Andy Shevchenko Reviewed-by: Tony Lindgren Signed-off-by: Ilpo Järvinen Link: https://lore.kernel.org/r/b4f428e9-491f-daf2-2232-819928dc276e@linux.intel.com Signed-off-by: Greg Kroah-Hartman

serial: 8250: fix XOFF/XON sending when DMA is used

2022-04-08T12:40:28+00:00

[ Upstream commit f58c252e30cf74f68b0054293adc03b5923b9f0e ] When 8250 UART is using DMA, x_char (XON/XOFF) is never sent to the wire. After this change, x_char is injected correctly. Create uart_xchar_out() helper for sending the x_char out and accounting related to it. It seems that almost every driver does these same steps with x_char. Except for 8250, however, almost all currently lack .serial_out so they cannot immediately take advantage of this new helper. The downside of this patch is that it might reintroduce the problems some devices faced with mixed DMA/non-DMA transfer which caused revert f967fc8f165f (Revert "serial: 8250_dma: don't bother DMA with small transfers"). However, the impact should be limited to cases with XON/XOFF (that didn't work with DMA capable devices to begin with so this problem is not very likely to cause a major issue, if any at all). Fixes: 9ee4b83e51f74 ("serial: 8250: Add support for dmaengine") Reported-by: Gilles Buloz Tested-by: Gilles Buloz Reviewed-by: Andy Shevchenko Signed-off-by: Ilpo Järvinen Link: https://lore.kernel.org/r/20220314091432.4288-2-ilpo.jarvinen@linux.intel.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin

treewide: Convert macro and uses of section(foo) to section("foo")

2020-10-25T21:51:49+00:00

Use a more generic form for __section that requires quotes to avoid complications with clang and gcc differences. Remove the quote operator # from compiler_attributes.h __section macro. Convert all unquoted __section(foo) uses to quoted __section("foo"). Also convert __attribute__((section("foo"))) uses to __section("foo") even if the __attribute__ has multiple list entry forms. Conversion done using the script at: https://lore.kernel.org/lkml/75393e5ddc272dc7403de74d645e6c6e0f4e70eb.camel@perches.com/2-convert_section.pl Signed-off-by: Joe Perches Reviewed-by: Nick Desaulniers Reviewed-by: Miguel Ojeda Signed-off-by: Linus Torvalds

serial: core: fix console port-lock regression

2020-09-16T11:22:44+00:00

Fix the port-lock initialisation regression introduced by commit a3cb39d258ef ("serial: core: Allow detach and attach serial device for console") by making sure that the lock is again initialised during console setup. The console may be registered before the serial controller has been probed in which case the port lock needs to be initialised during console setup by a call to uart_set_options(). The console-detach changes introduced a regression in several drivers by effectively removing that initialisation by not initialising the lock when the port is used as a console (which is always the case during console setup). Add back the early lock initialisation and instead use a new console-reinit flag to handle the case where a console is being re-attached through sysfs. The question whether the console-detach interface should have been added in the first place is left for another discussion. Note that the console-enabled check in uart_set_options() is not redundant because of kgdboc, which can end up reinitialising an already enabled console (see commit 42b6a1baa3ec ("serial_core: Don't re-initialize a previously initialized spinlock.")). Fixes: a3cb39d258ef ("serial: core: Allow detach and attach serial device for console") Cc: stable # 5.7 Signed-off-by: Johan Hovold Reviewed-by: Andy Shevchenko Link: https://lore.kernel.org/r/20200909143101.15389-3-johan@kernel.org Signed-off-by: Greg Kroah-Hartman

Merge 5.8-rc6 into tty-next

2020-07-20T07:39:11+00:00

We need the serial/tty fixes in here as well. Signed-off-by: Greg Kroah-Hartman

serial: core: drop redundant sysrq checks

2020-06-27T14:16:37+00:00

The sysrq timestamp will never be set unless port->has_sysrq is set (see uart_handle_break()) so drop the redundant checks that were added by commit 1997e9dfdc84 ("serial_core: Un-ifdef sysrq SUPPORT_SYSRQ"). Signed-off-by: Johan Hovold Reviewed-by: Andy Shevchenko Reviewed-by: Dmitry Safonov <0x7f454c46@gmail.com> Link: https://lore.kernel.org/r/20200610152232.16925-4-johan@kernel.org Signed-off-by: Greg Kroah-Hartman

serial: core: fix sysrq overhead regression

2020-06-27T14:16:37+00:00

Commit 8e20fc391711 ("serial_core: Move sysrq functions from header file") converted the inline sysrq helpers to exported functions which are now called for every received character, interrupt and break signal also on systems without CONFIG_MAGIC_SYSRQ_SERIAL instead of being optimised away by the compiler. Inlining these helpers again also avoids the function call overhead when CONFIG_MAGIC_SYSRQ_SERIAL is enabled (e.g. when the port is not used as a console). Fixes: 8e20fc391711 ("serial_core: Move sysrq functions from header file") Cc: Dmitry Safonov <0x7f454c46@gmail.com> Signed-off-by: Johan Hovold Cc: stable Reviewed-by: Andy Shevchenko Reviewed-by: Dmitry Safonov <0x7f454c46@gmail.com> Link: https://lore.kernel.org/r/20200610152232.16925-3-johan@kernel.org Signed-off-by: Greg Kroah-Hartman

Revert "serial: core: Refactor uart_unlock_and_check_sysrq()"

2020-06-27T14:16:37+00:00

This reverts commit da9a5aa3402db0ff3b57216d8dbf2478e1046cae. In order to ease backporting a fix for a sysrq regression, revert this rewrite which was since added on top. The other sysrq helpers now bail out early when sysrq is not enabled; it's better to keep that pattern here as well. Note that the __releases() attribute won't be needed after the follow-on fix either. Fixes: da9a5aa3402d ("serial: core: Refactor uart_unlock_and_check_sysrq()") Cc: stable Signed-off-by: Johan Hovold Reviewed-by: Andy Shevchenko Link: https://lore.kernel.org/r/20200610152232.16925-2-johan@kernel.org Signed-off-by: Greg Kroah-Hartman

kernel/linux.git/include/linux/serial_core.h, branch v5.10.185

serial: 8250: Let drivers request full 16550A feature probing

serial: Create uart_xmit_advance()

serial: 8250: Fix PM usage_count for console handover

serial: 8250: fix XOFF/XON sending when DMA is used

treewide: Convert macro and uses of __section(foo) to __section("foo")

serial: core: fix console port-lock regression

Merge 5.8-rc6 into tty-next

serial: core: drop redundant sysrq checks

serial: core: fix sysrq overhead regression

Revert "serial: core: Refactor uart_unlock_and_check_sysrq()"

treewide: Convert macro and uses of section(foo) to section("foo")