kernel/linux.git/drivers/tty/serial, branch linux-5.9.y

serial: 8250_omap: Avoid FIFO corruption caused by MDR1 access

2020-12-21T12:28:20+00:00

commit d96f04d347e4011977abdbb4da5d8f303ebd26f8 upstream. It has been observed that once per 300-1300 port openings the first transmitted byte is being corrupted on AM3352 ("v" written to FIFO appeared as "e" on the wire). It only happened if single byte has been transmitted right after port open, which means, DMA is not used for this transfer and the corruption never happened afterwards. Therefore I've carefully re-read the MDR1 errata (link below), which says "when accessing the MDR1 registers that causes a dummy under-run condition that will freeze the UART in IrDA transmission. In UART mode, this may corrupt the transferred data". Strictly speaking, omap_8250_mdr1_errataset() performs a read access and if the value is the same as should be written, exits without errata-recommended FIFO reset. A brief check of the serial_omap_mdr1_errataset() from the competing omap-serial driver showed it has no read access of MDR1. After removing the read access from omap_8250_mdr1_errataset() the data corruption never happened any more. Link: https://www.ti.com/lit/er/sprz360i/sprz360i.pdf Fixes: 61929cf0169d ("tty: serial: Add 8250-core based omap driver") Cc: stable@vger.kernel.org Signed-off-by: Alexander Sverdlin Link: https://lore.kernel.org/r/20201210055257.1053028-1-alexander.sverdlin@gmail.com Signed-off-by: Greg Kroah-Hartman

serial: ar933x_uart: disable clk on error handling path in probe

2020-11-24T12:39:10+00:00

commit 425af483523b76bc78e14674a430579d38b2a593 upstream. ar933x_uart_probe() does not invoke clk_disable_unprepare() on one error handling path. This patch fixes that. Fixes: 9be1064fe524 ("serial: ar933x_uart: add RS485 support") Reported-by: Hulk Robot Signed-off-by: Zheng Zengkai Link: https://lore.kernel.org/r/20201111124426.42638-1-zhengzengkai@huawei.com Cc: stable Signed-off-by: Greg Kroah-Hartman

tty: serial: imx: keep console clocks always on

2020-11-24T12:39:08+00:00

commit e67c139c488e84e7eae6c333231e791f0e89b3fb upstream. For below code, there has chance to cause deadlock in SMP system: Thread 1: clk_enable_lock(); pr_info("debug message"); clk_enable_unlock(); Thread 2: imx_uart_console_write() clk_enable() clk_enable_lock(); Thread 1: Acuired clk enable_lock -> printk -> console_trylock_spinning Thread 2: console_unlock() -> imx_uart_console_write -> clk_disable -> Acquite clk enable_lock So the patch is to keep console port clocks always on like other console drivers. Fixes: 1cf93e0d5488 ("serial: imx: remove the uart_console() check") Acked-by: Uwe Kleine-König Signed-off-by: Fugang Duan Link: https://lore.kernel.org/r/20201111025136.29818-1-fugang.duan@nxp.com Cc: stable [fix up build warning - gregkh] Signed-off-by: Greg Kroah-Hartman

tty: serial: imx: fix potential deadlock

2020-11-24T12:39:08+00:00

commit 33f16855dcb973f745c51882d0e286601ff3be2b upstream. Enabling the lock dependency validator has revealed that the way spinlocks are used in the IMX serial port could result in a deadlock. Specifically, imx_uart_int() acquires a spinlock without disabling the interrupts, meaning that another interrupt could come along and try to acquire the same spinlock, potentially causing the two to wait for each other indefinitely. Use spin_lock_irqsave() instead to disable interrupts upon acquisition of the spinlock. Fixes: c974991d2620 ("tty:serial:imx: use spin_lock instead of spin_lock_irqsave in isr") Reviewed-by: Uwe Kleine-König Signed-off-by: Sam Nobs Link: https://lore.kernel.org/r/1604955006-9363-1-git-send-email-samuel.nobs@taitradio.com Cc: stable Signed-off-by: Greg Kroah-Hartman

serial: txx9: add missing platform_driver_unregister() on error in serial_txx9_init

2020-11-10T11:39:09+00:00

commit 0c5fc92622ed5531ff324b20f014e9e3092f0187 upstream. Add the missing platform_driver_unregister() before return from serial_txx9_init in the error handling case when failed to register serial_txx9_pci_driver with macro ENABLE_SERIAL_TXX9_PCI defined. Fixes: ab4382d27412 ("tty: move drivers/serial/ to drivers/tty/serial/") Signed-off-by: Qinglang Miao Link: https://lore.kernel.org/r/20201103084942.109076-1-miaoqinglang@huawei.com Cc: stable Signed-off-by: Greg Kroah-Hartman

serial: 8250_mtk: Fix uart_get_baud_rate warning

2020-11-10T11:39:09+00:00

commit 912ab37c798770f21b182d656937072b58553378 upstream. Mediatek 8250 port supports speed higher than uartclk / 16. If the baud rates in both the new and the old termios setting are higher than uartclk / 16, the WARN_ON in uart_get_baud_rate() will be triggered. Passing NULL as the old termios so uart_get_baud_rate() will use uartclk / 16 - 1 as the new baud rate which will be replaced by the original baud rate later by tty_termios_encode_baud_rate() in mtk8250_set_termios(). Fixes: 551e553f0d4a ("serial: 8250_mtk: Fix high-speed baud rates clamping") Signed-off-by: Claire Chang Link: https://lore.kernel.org/r/20201102120749.374458-1-tientzu@chromium.org Cc: stable Signed-off-by: Greg Kroah-Hartman

tty: serial: imx: enable earlycon by default if IMX_SERIAL_CONSOLE is enabled

2020-11-10T11:39:07+00:00

commit 427627a23c3e86e31113f9db9bfdca41698a0ee5 upstream. Since 699cc4dfd140 (tty: serial: imx: add imx earlycon driver), the earlycon part of imx serial is a separate driver and isn't necessarily enabled anymore when the console is enabled. This causes users to loose the earlycon functionality when upgrading their kenrel configuration via oldconfig. Enable earlycon by default when IMX_SERIAL_CONSOLE is enabled. Fixes: 699cc4dfd140 (tty: serial: imx: add imx earlycon driver) Reviewed-by: Fabio Estevam Reviewed-by: Fugang Duan Signed-off-by: Lucas Stach Link: https://lore.kernel.org/r/20201105204026.1818219-1-l.stach@pengutronix.de Cc: stable Signed-off-by: Greg Kroah-Hartman

tty: serial: fsl_lpuart: LS1021A has a FIFO size of 16 words, like LS1028A

2020-11-05T10:51:40+00:00

commit c97f2a6fb3dfbfbbc88edc8ea62ef2b944e18849 upstream. Prior to the commit that this one fixes, the FIFO size was derived from the read-only register LPUARTx_FIFO[TXFIFOSIZE] using the following formula: TX FIFO size = 2 ^ (LPUARTx_FIFO[TXFIFOSIZE] - 1) The documentation for LS1021A is a mess. Under chapter 26.1.3 LS1021A LPUART module special consideration, it mentions TXFIFO_SZ and RXFIFO_SZ being equal to 4, and in the register description for LPUARTx_FIFO, it shows the out-of-reset value of TXFIFOSIZE and RXFIFOSIZE fields as "011", even though these registers read as "101" in reality. And when LPUART on LS1021A was working, the "101" value did correspond to "16 datawords", by applying the formula above, even though the documentation is wrong again (!!!!) and says that "101" means 64 datawords (hint: it doesn't). So the "new" formula created by commit f77ebb241ce0 has all the premises of being wrong for LS1021A, because it relied only on false data and no actual experimentation. Interestingly, in commit c2f448cff22a ("tty: serial: fsl_lpuart: add LS1028A support"), Michael Walle applied a workaround to this by manually setting the FIFO widths for LS1028A. It looks like the same values are used by LS1021A as well, in fact. When the driver thinks that it has a deeper FIFO than it really has, getty (user space) output gets truncated. Many thanks to Michael for pointing out where to look. Fixes: f77ebb241ce0 ("tty: serial: fsl_lpuart: correct the FIFO depth size") Suggested-by: Michael Walle Signed-off-by: Vladimir Oltean Link: https://lore.kernel.org/r/20201023013429.3551026-1-vladimir.oltean@nxp.com Reviewed-by：Fugang Duan Cc: stable Signed-off-by: Greg Kroah-Hartman

tty: serial: 21285: fix lockup on open

2020-11-05T10:51:40+00:00

commit 82776f6c75a90e1d2103e689b84a689de8f1aa02 upstream. Commit 293f89959483 ("tty: serial: 21285: stop using the unused[] variable from struct uart_port") introduced a bug which stops the transmit interrupt being disabled when there are no characters to transmit - disabling the transmit interrupt at the interrupt controller is the only way to stop an interrupt storm. If this interrupt is not disabled when there are no transmit characters, we end up with an interrupt storm which prevents the machine making forward progress. Fixes: 293f89959483 ("tty: serial: 21285: stop using the unused[] variable from struct uart_port") Signed-off-by: Russell King Cc: stable Link: https://lore.kernel.org/r/E1kU4GS-0006lE-OO@rmk-PC.armlinux.org.uk Signed-off-by: Greg Kroah-Hartman

serial: pl011: Fix lockdep splat when handling magic-sysrq interrupt

2020-11-01T11:47:09+00:00

commit 534cf755d9df99e214ddbe26b91cd4d81d2603e2 upstream. Issuing a magic-sysrq via the PL011 causes the following lockdep splat, which is easily reproducible under QEMU: | sysrq: Changing Loglevel | sysrq: Loglevel set to 9 | | ====================================================== | WARNING: possible circular locking dependency detected | 5.9.0-rc7 #1 Not tainted | ------------------------------------------------------ | systemd-journal/138 is trying to acquire lock: | ffffab133ad950c0 (console_owner){-.-.}-{0:0}, at: console_lock_spinning_enable+0x34/0x70 | | but task is already holding lock: | ffff0001fd47b098 (&port_lock_key){-.-.}-{2:2}, at: pl011_int+0x40/0x488 | | which lock already depends on the new lock. [...] | Possible unsafe locking scenario: | | CPU0 CPU1 | ---- ---- | lock(&port_lock_key); | lock(console_owner); | lock(&port_lock_key); | lock(console_owner); | | *** DEADLOCK *** The issue being that CPU0 takes 'port_lock' on the irq path in pl011_int() before taking 'console_owner' on the printk() path, whereas CPU1 takes the two locks in the opposite order on the printk() path due to setting the "console_owner" prior to calling into into the actual console driver. Fix this in the same way as the msm-serial driver by dropping 'port_lock' before handling the sysrq. Cc: # 4.19+ Cc: Russell King Cc: Greg Kroah-Hartman Cc: Jiri Slaby Link: https://lore.kernel.org/r/20200811101313.GA6970@willie-the-truck Signed-off-by: Peter Zijlstra Tested-by: Will Deacon Signed-off-by: Will Deacon Link: https://lore.kernel.org/r/20200930120432.16551-1-will@kernel.org Signed-off-by: Greg Kroah-Hartman