kernel/linux.git/drivers/tty/serial/msm_serial.c, branch v4.9.331

serial: msm_serial: disable interrupts in __msm_console_write()

2022-06-14T14:52:40+00:00

[ Upstream commit aabdbb1b7a5819e18c403334a31fb0cc2c06ad41 ] __msm_console_write() assumes that interrupts are disabled, but with threaded console printers it is possible that the write() callback of the console is called with interrupts enabled. Explicitly disable interrupts using local_irq_save() to preserve the assumed context. Reported-by: Marek Szyprowski Reviewed-by: Petr Mladek Signed-off-by: John Ogness Link: https://lore.kernel.org/r/20220506213324.470461-1-john.ogness@linutronix.de Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin

tty: serial: msm_serial: Deactivate RX DMA for polling support

2021-12-08T07:45:07+00:00

commit 7492ffc90fa126afb67d4392d56cb4134780194a upstream. The CONSOLE_POLLING mode is used for tools like k(g)db. In this kind of setup, it is often sharing a serial device with the normal system console. This is usually no problem because the polling helpers can consume input values directly (when in kgdb context) and the normal Linux handlers can only consume new input values after kgdb switched back. This is not true anymore when RX DMA is enabled for UARTDM controllers. Single input values can no longer be received correctly. Instead following seems to happen: * on 1. input, some old input is read (continuously) * on 2. input, two old inputs are read (continuously) * on 3. input, three old input values are read (continuously) * on 4. input, 4 previous inputs are received This repeats then for each group of 4 input values. This behavior changes slightly depending on what state the controller was when the first input was received. But this makes working with kgdb basically impossible because control messages are always corrupted when kgdboc tries to parse them. RX DMA should therefore be off when CONSOLE_POLLING is enabled to avoid these kind of problems. No such problem was noticed for TX DMA. Fixes: 99693945013a ("tty: serial: msm: Add RX DMA support") Cc: stable@vger.kernel.org Signed-off-by: Sven Eckelmann Link: https://lore.kernel.org/r/20211113121050.7266-1-sven@narfation.org Signed-off-by: Greg Kroah-Hartman

tty: serial: msm_serial: Fix lockup for sysrq and oops

2020-01-12T10:24:17+00:00

commit 0e4f7f920a5c6bfe5e851e989f27b35a0cc7fb7e upstream. As the commit 677fe555cbfb ("serial: imx: Fix recursive locking bug") has mentioned the uart driver might cause recursive locking between normal printing and the kernel debugging facilities (e.g. sysrq and oops). In the commit it gave out suggestion for fixing recursive locking issue: "The solution is to avoid locking in the sysrq case and trylock in the oops_in_progress case." This patch follows the suggestion (also used the exactly same code with other serial drivers, e.g. amba-pl011.c) to fix the recursive locking issue, this can avoid stuck caused by deadlock and print out log for sysrq and oops. Fixes: 04896a77a97b ("msm_serial: serial driver for MSM7K onboard serial peripheral.") Signed-off-by: Leo Yan Reviewed-by: Jeffrey Hugo Link: https://lore.kernel.org/r/20191127141544.4277-2-leo.yan@linaro.org Signed-off-by: Greg Kroah-Hartman Signed-off-by: Greg Kroah-Hartman

tty: serial: msm_serial: Fix flow control

2019-12-21T09:40:44+00:00

commit b027ce258369cbfa88401a691c23dad01deb9f9b upstream. hci_qca interfaces to the wcn3990 via a uart_dm on the msm8998 mtp and Lenovo Miix 630 laptop. As part of initializing the wcn3990, hci_qca disables flow, configures the uart baudrate, and then reenables flow - at which point an event is expected to be received over the uart from the wcn3990. It is observed that this event comes after the baudrate change but before hci_qca re-enables flow. This is unexpected, and is a result of msm_reset() being broken. According to the uart_dm hardware documentation, it is recommended that automatic hardware flow control be enabled by setting RX_RDY_CTL. Auto hw flow control will manage RFR based on the configured watermark. When there is space to receive data, the hw will assert RFR. When the watermark is hit, the hw will de-assert RFR. The hardware documentation indicates that RFR can me manually managed via CR when RX_RDY_CTL is not set. SET_RFR asserts RFR, and RESET_RFR de-asserts RFR. msm_reset() is broken because after resetting the hardware, it unconditionally asserts RFR via SET_RFR. This enables flow regardless of the current configuration, and would undo a previous flow disable operation. It should instead de-assert RFR via RESET_RFR to block flow until the hardware is reconfigured. msm_serial should rely on the client to specify that flow should be enabled, either via mctrl() or the termios structure, and only assert RFR in response to those triggers. Fixes: 04896a77a97b ("msm_serial: serial driver for MSM7K onboard serial peripheral.") Signed-off-by: Jeffrey Hugo Reviewed-by: Bjorn Andersson Cc: stable Reviewed-by: Andy Gross Link: https://lore.kernel.org/r/20191021154616.25457-1-jeffrey.l.hugo@gmail.com Signed-off-by: Greg Kroah-Hartman

tty: serial: msm_serial: avoid system lockup condition

2019-08-04T07:33:37+00:00

[ Upstream commit ba3684f99f1b25d2a30b6956d02d339d7acb9799 ] The function msm_wait_for_xmitr can be taken with interrupts disabled. In order to avoid a potential system lockup - demonstrated under stress testing conditions on SoC QCS404/5 - make sure we wait for a bounded amount of time. Tested on SoC QCS404. Signed-off-by: Jorge Ramirez-Ortiz Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin

tty: serial: msm_serial: Fix XON/XOFF

2019-06-11T10:22:42+00:00

commit 61c0e37950b88bad590056286c1d766b1f167f4e upstream. When the tty layer requests the uart to throttle, the current code executing in msm_serial will trigger "Bad mode in Error Handler" and generate an invalid stack frame in pstore before rebooting (that is if pstore is indeed configured: otherwise the user shall just notice a reboot with no further information dumped to the console). This patch replaces the PIO byte accessor with the word accessor already used in PIO mode. Fixes: 68252424a7c7 ("tty: serial: msm: Support big-endian CPUs") Cc: stable@vger.kernel.org Signed-off-by: Jorge Ramirez-Ortiz Reviewed-by: Bjorn Andersson Reviewed-by: Stephen Boyd Signed-off-by: Greg Kroah-Hartman

tty: serial: msm: Fix module autoload

2017-02-26T10:10:51+00:00

commit abe81f3b8ed2996e1712d26d38ff6b73f582c616 upstream. If the driver is built as a module, autoload won't work because the module alias information is not filled. So user-space can't match the registered device with the corresponding module. Export the module alias information using the MODULE_DEVICE_TABLE() macro. Before this patch: $ modinfo drivers/tty/serial/msm_serial.ko | grep alias $ After this patch: $ modinfo drivers/tty/serial/msm_serial.ko | grep alias alias: of:N*T*Cqcom,msm-uartdmC* alias: of:N*T*Cqcom,msm-uartdm alias: of:N*T*Cqcom,msm-uartC* alias: of:N*T*Cqcom,msm-uart Signed-off-by: Javier Martinez Canillas Acked-by: Bjorn Andersson Cc: stable Signed-off-by: Greg Kroah-Hartman Signed-off-by: Greg Kroah-Hartman

tty: serial: msm: fix definition of msm_stop_dma

2016-06-25T17:23:54+00:00

The msm_stop_dma() is not exported from the driver, so make it static to stop the following warning: drivers/tty/serial/msm_serial.c:84:6: warning: symbol 'msm_stop_dma' was not declared. Should it be static? Signed-off-by: Ben Dooks Acked-by: Andy Gross Reviewed-by: Bjorn Andersson Reviewed-by: Stephen Boyd Signed-off-by: Greg Kroah-Hartman

tty: serial: msm: Don't read off end of tx fifo

2016-06-25T17:23:54+00:00

For dm uarts in pio mode tx data is transferred to the fifo register 4 bytes at a time, but care is not taken when these 4 bytes spans the end of the xmit buffer so the loop might read up to 3 bytes past the buffer and then skip the actual data at the beginning of the buffer. Fix this by, analogous to the DMA case, make sure the chunk doesn't wrap the xmit buffer. Fixes: 3a878c430fd6 ("tty: serial: msm: Add TX DMA support") Cc: Ivan Ivanov Cc: stable@vger.kernel.org Reported-by: Frank Rowand Reported-by: Nicolas Dechesne Signed-off-by: Bjorn Andersson Acked-by: Andy Gross Tested-by: Frank Rowand Reviewed-by: Stephen Boyd Signed-off-by: Greg Kroah-Hartman

tty:serial:msm:Do not restore Rx interrupts in DMA

2016-06-25T17:23:54+00:00

Avoid data corruption issues that result in CRC errors during file transfers over serial ports at higher baud rates. The current msm_serial driver masks the FIFO Rx interrupts in msm_start_rx_dma() since Rx FIFO interrupts are not required in DMA mode. However, msm_complete_rx_dma() re-enables the Rx FIFO interrupts which could cause RXSTALE event to be processed when a TXLEV interrupt occurs. The following is the sequence of events that could occur resulting in data corruption. msm_start_rx_dma -> msm_complete_rx_dma --> spin_unlock_irqrestore(&port->lock) --> msm_uart_irq()(For TXLEV interrupt) --> msm_handle_rx_dm() (Read from FIFO resulting in data corruption) The patch fixes the issue by not restoring the RXLEV and RXSTALE interrupts in msm_complete_rx_dma(). These interrupts are required only in FIFO mode. Signed-off-by: Charanya Venkatraman Acked-by: Andy Gross Reviewed-by: Stephen Boyd Signed-off-by: Greg Kroah-Hartman