kernel/drivers/tty/serial/meson_uart.c, branch linux-rolling-stable

serial: Switch back to struct platform_driver::remove()

2024-10-11T06:13:28Z

After commit 0edb555a65d1 ("platform: Make platform_driver::remove() return void") .remove() is (again) the right callback to implement for platform drivers. Convert all platform drivers below drivers/tty/serial to use .remove(), with the eventual goal to drop struct platform_driver::remove_new(). As .remove() and .remove_new() have the same prototypes, conversion is done by just changing the structure member name in the driver initializer. Signed-off-by: Uwe Kleine-König Link: https://lore.kernel.org/r/20241007205803.444994-7-u.kleine-koenig@baylibre.com Signed-off-by: Greg Kroah-Hartman

serial: meson+qcom: don't advance the kfifo twice

2024-04-16T07:05:43Z

Marek reports, that the -next commit 1788cf6a91d9 (tty: serial: switch from circ_buf to kfifo) broke meson_uart and qcom_geni_serial. The commit mistakenly advanced the kfifo twice: once by uart_fifo_get()/kfifo_out() and second time by uart_xmit_advance(). To advance the fifo only once, drop the superfluous uart_xmit_advance() from both. To count the TX statistics properly, use uart_fifo_out() in qcom_geni_serial (meson_uart_start_tx() already uses that). I checked all other uses of uart_xmit_advance() and they appear correct: either they are finishing DMA transfers or are after peek/linear_ptr (i.e. they do not advance fifo). Signed-off-by: Jiri Slaby (SUSE) Reported-by: Marek Szyprowski Fixes: 1788cf6a91d9 ("tty: serial: switch from circ_buf to kfifo") Cc: Neil Armstrong Cc: Kevin Hilman Cc: Jerome Brunet Cc: Martin Blumenstingl Link: https://lore.kernel.org/r/20240416054825.6211-1-jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman

tty: serial: switch from circ_buf to kfifo

2024-04-09T13:28:03Z

Switch from struct circ_buf to proper kfifo. kfifo provides much better API, esp. when wrap-around of the buffer needs to be taken into account. Look at pl011_dma_tx_refill() or cpm_uart_tx_pump() changes for example. Kfifo API can also fill in scatter-gather DMA structures, so it easier for that use case too. Look at lpuart_dma_tx() for example. Note that not all drivers can be converted to that (like atmel_serial), they handle DMA specially. Note that usb-serial uses kfifo for TX for ages. omap needed a bit more care as it needs to put a char into FIFO to start the DMA transfer when OMAP_DMA_TX_KICK is set. In that case, we have to do kfifo_dma_out_prepare twice: once to find out the tx_size (to find out if it is worths to do DMA at all -- size >= 4), the second time for the actual transfer. All traces of circ_buf are removed from serial_core.h (and its struct uart_state). Signed-off-by: Jiri Slaby (SUSE) Cc: Al Cooper Cc: Matthias Brugger Cc: AngeloGioacchino Del Regno Cc: Kumaravel Thiagarajan Cc: Tharun Kumar P Cc: Russell King Cc: Vineet Gupta Cc: Richard Genoud Cc: Nicolas Ferre Cc: Alexandre Belloni Cc: Claudiu Beznea Cc: Alexander Shiyan Cc: Baruch Siach Cc: Maciej W. Rozycki Cc: Shawn Guo Cc: Sascha Hauer Cc: Fabio Estevam Cc: Neil Armstrong Cc: Kevin Hilman Cc: Jerome Brunet Cc: Martin Blumenstingl Cc: Taichi Sugaya Cc: Takao Orito Cc: Bjorn Andersson Cc: Konrad Dybcio Cc: Pali Rohár Cc: Michael Ellerman Cc: Nicholas Piggin Cc: Christophe Leroy Cc: Aneesh Kumar K.V Cc: Naveen N. Rao Cc: Manivannan Sadhasivam Cc: Krzysztof Kozlowski Cc: Alim Akhtar Cc: Laxman Dewangan Cc: Thierry Reding Cc: Jonathan Hunter Cc: Orson Zhai Cc: Baolin Wang Cc: Chunyan Zhang Cc: Patrice Chotard Cc: Maxime Coquelin Cc: Alexandre Torgue Cc: David S. Miller Cc: Hammer Hsieh Cc: Peter Korsgaard Cc: Timur Tabi Cc: Michal Simek Cc: Sumit Semwal Cc: Christian König Link: https://lore.kernel.org/r/20240405060826.2521-13-jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman

serial: meson: Use uart_prepare_sysrq_char().

2024-03-02T21:06:21Z

The port lock is a spinlock_t which is becomes a sleeping lock on PREEMPT_RT. The driver splits the locking function into two parts: local_irq_save() and uart_port_lock() and this breaks PREEMPT_RT. Delay handling sysrq until port lock is dropped. Remove the special case in the console write routine an always use the complete locking function. Cc: Kevin Hilman Cc: Jerome Brunet Cc: linux-arm-kernel@lists.infradead.org Cc: linux-amlogic@lists.infradead.org Signed-off-by: Sebastian Andrzej Siewior Link: https://lore.kernel.org/r/20240301215246.891055-5-bigeasy@linutronix.de Signed-off-by: Greg Kroah-Hartman

serial: meson: Convert to platform remove callback returning void

2023-11-23T19:12:32Z

The .remove() callback for a platform driver returns an int which makes many driver authors wrongly assume it's possible to do error handling by returning an error code. However the value returned is ignored (apart from emitting a warning) and this typically results in resource leaks. To improve here there is a quest to make the remove callback return void. In the first step of this quest all drivers are converted to .remove_new(), which already returns void. Eventually after all drivers are converted, .remove_new() will be renamed to .remove(). Trivially convert this driver from always returning zero in the remove callback to the void returning variant. Signed-off-by: Uwe Kleine-König Link: https://lore.kernel.org/r/20231110152927.70601-24-u.kleine-koenig@pengutronix.de Signed-off-by: Greg Kroah-Hartman

tty: serial: meson: fix hard LOCKUP on crtscts mode

2023-10-17T08:17:01Z

There might be hard lockup if we set crtscts mode on port without RTS/CTS configured: # stty -F /dev/ttyAML6 crtscts; echo 1 > /dev/ttyAML6; echo 2 > /dev/ttyAML6 [ 95.890386] rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: [ 95.890857] rcu: 3-...0: (201 ticks this GP) idle=e33c/1/0x4000000000000000 softirq=5844/5846 fqs=4984 [ 95.900212] rcu: (detected by 2, t=21016 jiffies, g=7753, q=296 ncpus=4) [ 95.906972] Task dump for CPU 3: [ 95.910178] task:bash state:R running task stack:0 pid:205 ppid:1 flags:0x00000202 [ 95.920059] Call trace: [ 95.922485] __switch_to+0xe4/0x168 [ 95.925951] 0xffffff8003477508 [ 95.974379] watchdog: Watchdog detected hard LOCKUP on cpu 3 [ 95.974424] Modules linked in: 88x2cs(O) rtc_meson_vrtc Possible solution would be to not allow to setup crtscts on such port. Tested on S905X3 based board. Fixes: ff7693d079e5 ("ARM: meson: serial: add MesonX SoC on-chip uart driver") Cc: stable@vger.kernel.org Signed-off-by: Pavel Krasavin Reviewed-by: Neil Armstrong Reviewed-by: Dmitry Rokosov v6: stable tag added v5: https://lore.kernel.org/lkml/OF43DA36FF.2BD3BB21-ON00258A47.005A8125-00258A47.005A9513@gdc.ru/ added missed Reviewed-by tags, Fixes tag added according to Dmitry and Neil notes v4: https://lore.kernel.org/lkml/OF55521400.7512350F-ON00258A47.003F7254-00258A47.0040E15C@gdc.ru/ More correct patch subject according to Jiri's note v3: https://lore.kernel.org/lkml/OF6CF5FFA0.CCFD0E8E-ON00258A46.00549EDF-00258A46.0054BB62@gdc.ru/ "From:" line added to the mail v2: https://lore.kernel.org/lkml/OF950BEF72.7F425944-ON00258A46.00488A76-00258A46.00497D44@gdc.ru/ braces for single statement removed according to Dmitry's note v1: https://lore.kernel.org/lkml/OF28B2B8C9.5BC0CD28-ON00258A46.0037688F-00258A46.0039155B@gdc.ru/ Link: https://lore.kernel.org/r/OF66360032.51C36182-ON00258A48.003F656B-00258A48.0040092C@gdc.ru Signed-off-by: Greg Kroah-Hartman

tty: serial: meson: Add a earlycon for the S4 SoC

2023-10-10T06:50:49Z

The new Amlogic S4 SoC does not have a always-on uart, so add OF_EARLYCON_DECLARE for it. Amlogic T7 will use this as fallback. Signed-off-by: Lucas Tanure Reviewed-by: Neil Armstrong Link: https://lore.kernel.org/r/20231009121151.4509-1-tanure@linux.com Signed-off-by: Greg Kroah-Hartman

serial: meson: Use port lock wrappers

2023-09-18T09:18:12Z

When a serial port is used for kernel console output, then all modifications to the UART registers which are done from other contexts, e.g. getty, termios, are interference points for the kernel console. So far this has been ignored and the printk output is based on the principle of hope. The rework of the console infrastructure which aims to support threaded and atomic consoles, requires to mark sections which modify the UART registers as unsafe. This allows the atomic write function to make informed decisions and eventually to restore operational state. It also allows to prevent the regular UART code from modifying UART registers while printk output is in progress. All modifications of UART registers are guarded by the UART port lock, which provides an obvious synchronization point with the console infrastructure. To avoid adding this functionality to all UART drivers, wrap the spin_[un]lock*() invocations for uart_port::lock into helper functions which just contain the spin_[un]lock*() invocations for now. In a subsequent step these helpers will gain the console synchronization mechanisms. Converted with coccinelle. No functional change. Signed-off-by: Thomas Gleixner Acked-by: Neil Armstrong Signed-off-by: John Ogness Link: https://lore.kernel.org/r/20230914183831.587273-38-john.ogness@linutronix.de Signed-off-by: Greg Kroah-Hartman

Revert "tty: serial: meson: Add a earlycon for the T7 SoC"

2023-08-27T09:43:01Z

This reverts commit 6a4197f9763325043abf7690a21124a9facbf52e New SoC will use ttyS0 instead of ttyAML, so T7 SoC doesn't need a OF_EARLYCON_DECLARE. Fixes: 6a4197f97633 ("tty: serial: meson: Add a earlycon for the T7 SoC") Signed-off-by: Lucas Tanure Link: https://lore.kernel.org/r/20230827082944.5100-1-tanure@linux.com Signed-off-by: Greg Kroah-Hartman

tty: serial: meson: Add a earlycon for the T7 SoC

2023-08-22T13:29:01Z

The new Amlogic T7 SoC does not have a always-on uart, so add OF_EARLYCON_DECLARE for it. Signed-off-by: Lucas Tanure Acked-by: Neil Armstrong Link: https://lore.kernel.org/r/20230814080128.143613-2-tanure@linux.com Signed-off-by: Greg Kroah-Hartman