linux-stable.git/drivers/tty/serial, branch linux-5.10.y Linux kernel stable tree serial: 8250: Add late synchronize_irq() to shutdown to handle DW UART BUSY 2026-04-18T08:30:58+00:00 Ilpo Järvinen ilpo.jarvinen@linux.intel.com 2026-02-03T17:10:48+00:00 f1274a59bd4912f5da478983ff59d4928d3935ef commit e0a368ae79531ff92105a2692f10d83052055856 upstream. When DW UART is !uart_16550_compatible, it can indicate BUSY at any point (when under constant Rx pressure) unless a complex sequence of steps is performed. Any LCR write can run a foul with the condition that prevents writing LCR while the UART is BUSY, which triggers BUSY_DETECT interrupt that seems unmaskable using IER bits. Normal flow is that dw8250_handle_irq() handles BUSY_DETECT condition by reading USR register. This BUSY feature, however, breaks the assumptions made in serial8250_do_shutdown(), which runs synchronize_irq() after clearing IER and assumes no interrupts can occur after that point but then proceeds to update LCR, which on DW UART can trigger an interrupt. If serial8250_do_shutdown() releases the interrupt handler before the handler has run and processed the BUSY_DETECT condition by read the USR register, the IRQ is not deasserted resulting in interrupt storm that triggers "irq x: nobody cared" warning leading to disabling the IRQ. Add late synchronize_irq() into serial8250_do_shutdown() to ensure BUSY_DETECT from DW UART is handled before port's interrupt handler is released. Alternative would be to add DW UART specific shutdown function but it would mostly duplicate the generic code and the extra synchronize_irq() seems pretty harmless in serial8250_do_shutdown(). Fixes: 7d4008ebb1c9 ("tty: add a DesignWare 8250 driver") Cc: stable <stable@kernel.org> Reported-by: Bandal, Shankar <shankar.bandal@intel.com> Tested-by: Bandal, Shankar <shankar.bandal@intel.com> Tested-by: Murthy, Shanth <shanth.murthy@intel.com> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Link: https://patch.msgid.link/20260203171049.4353-7-ilpo.jarvinen@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit e0a368ae79531ff92105a2692f10d83052055856 upstream.

When DW UART is !uart_16550_compatible, it can indicate BUSY at any
point (when under constant Rx pressure) unless a complex sequence of
steps is performed. Any LCR write can run a foul with the condition
that prevents writing LCR while the UART is BUSY, which triggers
BUSY_DETECT interrupt that seems unmaskable using IER bits.

Normal flow is that dw8250_handle_irq() handles BUSY_DETECT condition
by reading USR register. This BUSY feature, however, breaks the
assumptions made in serial8250_do_shutdown(), which runs
synchronize_irq() after clearing IER and assumes no interrupts can
occur after that point but then proceeds to update LCR, which on DW
UART can trigger an interrupt.

If serial8250_do_shutdown() releases the interrupt handler before the
handler has run and processed the BUSY_DETECT condition by read the USR
register, the IRQ is not deasserted resulting in interrupt storm that
triggers "irq x: nobody cared" warning leading to disabling the IRQ.

Add late synchronize_irq() into serial8250_do_shutdown() to ensure
BUSY_DETECT from DW UART is handled before port's interrupt handler is
released. Alternative would be to add DW UART specific shutdown
function but it would mostly duplicate the generic code and the extra
synchronize_irq() seems pretty harmless in serial8250_do_shutdown().

Fixes: 7d4008ebb1c9 ("tty: add a DesignWare 8250 driver")
Cc: stable <stable@kernel.org>
Reported-by: Bandal, Shankar <shankar.bandal@intel.com>
Tested-by: Bandal, Shankar <shankar.bandal@intel.com>
Tested-by: Murthy, Shanth <shanth.murthy@intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://patch.msgid.link/20260203171049.4353-7-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
serial: 8250: Fix TX deadlock when using DMA 2026-04-18T08:30:58+00:00 Raul E Rangel rrangel@chromium.org 2026-02-09T20:58:18+00:00 8190f9ab6ad90cb97652adbebd238b874a4ef70d commit a424a34b8faddf97b5af41689087e7a230f79ba7 upstream. `dmaengine_terminate_async` does not guarantee that the `__dma_tx_complete` callback will run. The callback is currently the only place where `dma->tx_running` gets cleared. If the transaction is canceled and the callback never runs, then `dma->tx_running` will never get cleared and we will never schedule new TX DMA transactions again. This change makes it so we clear `dma->tx_running` after we terminate the DMA transaction. This is "safe" because `serial8250_tx_dma_flush` is holding the UART port lock. The first thing the callback does is also grab the UART port lock, so access to `dma->tx_running` is serialized. Fixes: 9e512eaaf8f4 ("serial: 8250: Fix fifo underflow on flush") Cc: stable <stable@kernel.org> Signed-off-by: Raul E Rangel <rrangel@google.com> Link: https://patch.msgid.link/20260209135815.1.I16366ecb0f62f3c96fe3dd5763fcf6f3c2b4d8cd@changeid Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit a424a34b8faddf97b5af41689087e7a230f79ba7 upstream.

`dmaengine_terminate_async` does not guarantee that the
`__dma_tx_complete` callback will run. The callback is currently the
only place where `dma->tx_running` gets cleared. If the transaction is
canceled and the callback never runs, then `dma->tx_running` will never
get cleared and we will never schedule new TX DMA transactions again.

This change makes it so we clear `dma->tx_running` after we terminate
the DMA transaction. This is "safe" because `serial8250_tx_dma_flush`
is holding the UART port lock. The first thing the callback does is also
grab the UART port lock, so access to `dma->tx_running` is serialized.

Fixes: 9e512eaaf8f4 ("serial: 8250: Fix fifo underflow on flush")
Cc: stable <stable@kernel.org>
Signed-off-by: Raul E Rangel <rrangel@google.com>
Link: https://patch.msgid.link/20260209135815.1.I16366ecb0f62f3c96fe3dd5763fcf6f3c2b4d8cd@changeid
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
serial: 8250_pci: add support for the AX99100 2026-04-18T08:30:58+00:00 Martin Roukala (né Peres) martin.roukala@mupuf.org 2026-03-09T13:53:10+00:00 bb3778f058d97d9496a7b321d1ba09d03a6e9e8a commit 9c0072bc33d349c83d223e64be30794e11938a6b upstream. This is found in popular brands such as StarTech.com or Delock, and has been a source of frustration to quite a few people, if I can trust Amazon comments complaining about Linux support via the official out-of-the-tree driver. Signed-off-by: Martin Roukala (né Peres) <martin.roukala@mupuf.org> Cc: stable <stable@kernel.org> Link: https://patch.msgid.link/20260309-8250_pci_ax99100-v1-1-3328bdfd8e94@mupuf.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 9c0072bc33d349c83d223e64be30794e11938a6b upstream.

This is found in popular brands such as StarTech.com or Delock, and has
been a source of frustration to quite a few people, if I can trust
Amazon comments complaining about Linux support via the official
out-of-the-tree driver.

Signed-off-by: Martin Roukala (né Peres) <martin.roukala@mupuf.org>
Cc: stable <stable@kernel.org>
Link: https://patch.msgid.link/20260309-8250_pci_ax99100-v1-1-3328bdfd8e94@mupuf.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
serial: 8250: 8250_omap.c: Clear DMA RX running status only after DMA termination is done 2026-03-04T12:20:06+00:00 Moteen Shah m-shah@ti.com 2026-01-12T08:18:29+00:00 b11ecb7f185c722f6f944da38cede7ed273f059d [ Upstream commit a5fd8945a478ff9be14812693891d7c9b4185a50 ] Clear rx_running flag only after DMA teardown polling completes. In the previous implementation the flag was being cleared while hardware teardown was still in progress, creating a mismatch between software state (flag = 0, "ready") and hardware state (still terminating). Signed-off-by: Moteen Shah <m-shah@ti.com> Link: https://patch.msgid.link/20260112081829.63049-3-m-shah@ti.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit a5fd8945a478ff9be14812693891d7c9b4185a50 ]

Clear rx_running flag only after DMA teardown polling completes. In the
previous implementation the flag was being cleared while hardware teardown
was still in progress, creating a mismatch between software state
(flag = 0, "ready") and hardware state (still terminating).

Signed-off-by: Moteen Shah <m-shah@ti.com>
Link: https://patch.msgid.link/20260112081829.63049-3-m-shah@ti.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
serial: 8250_dw: handle clock enable errors in runtime_resume 2026-03-04T12:20:06+00:00 Artem Shimko a.shimko.dev@gmail.com 2025-11-04T14:54:25+00:00 0d3ad1e8fea29f44a16150117b639e9d8d6445a3 [ Upstream commit d31228143a489ba6ba797896a07541ce06828c09 ] Add error checking for clk_prepare_enable() calls in dw8250_runtime_resume(). Currently if either clock fails to enable, the function returns success while leaving clocks in inconsistent state. This change implements comprehensive error handling by checking the return values of both clk_prepare_enable() calls. If the second clock enable operation fails after the first clock has already been successfully enabled, the code now properly cleans up by disabling and unpreparing the first clock before returning. The error code is then propagated to the caller, ensuring that clock enable failures are properly reported rather than being silently ignored. Signed-off-by: Artem Shimko <a.shimko.dev@gmail.com> Link: https://patch.msgid.link/20251104145433.2316165-2-a.shimko.dev@gmail.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit d31228143a489ba6ba797896a07541ce06828c09 ]

Add error checking for clk_prepare_enable() calls in
dw8250_runtime_resume(). Currently if either clock fails to enable,
the function returns success while leaving clocks in inconsistent state.

This change implements comprehensive error handling by checking the return
values of both clk_prepare_enable() calls. If the second clock enable
operation fails after the first clock has already been successfully
enabled, the code now properly cleans up by disabling and unpreparing
the first clock before returning. The error code is then propagated to
the caller, ensuring that clock enable failures are properly reported
rather than being silently ignored.

Signed-off-by: Artem Shimko <a.shimko.dev@gmail.com>
Link: https://patch.msgid.link/20251104145433.2316165-2-a.shimko.dev@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
serial: SH_SCI: improve "DMA support" prompt 2026-03-04T12:19:43+00:00 Randy Dunlap rdunlap@infradead.org 2026-01-10T23:26:43+00:00 5e8d73619bfd4954624a8e48589ada6b411f1035 [ Upstream commit 93bb95a11238d66a4c9aa6eabf9774b073a5895c ] Having a prompt of "DMA support" suddenly appear during a "make oldconfig" can be confusing. Add a little helpful text to the prompt message. Fixes: 73a19e4c0301 ("serial: sh-sci: Add DMA support.") Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be> Link: https://patch.msgid.link/20260110232643.3533351-5-rdunlap@infradead.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 93bb95a11238d66a4c9aa6eabf9774b073a5895c ]

Having a prompt of "DMA support" suddenly appear during a
"make oldconfig" can be confusing. Add a little helpful text to
the prompt message.

Fixes: 73a19e4c0301 ("serial: sh-sci: Add DMA support.")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://patch.msgid.link/20260110232643.3533351-5-rdunlap@infradead.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
serial: imx: change SERIAL_IMX_CONSOLE to bool 2026-03-04T12:19:43+00:00 Randy Dunlap rdunlap@infradead.org 2026-01-10T23:26:40+00:00 caad43c4f2033d1e3b5a0eb96cc5511f02a4d7b7 [ Upstream commit 79527d86ba91c2d9354832d19fd12b3baa66bd10 ] SERIAL_IMX_CONSOLE is a build option for the imx driver (SERIAL_IMX). It does not build a separate console driver file, so it can't be built as a module since it isn't built at all. Change the Kconfig symbol from tristate to bool and update the help text accordingly. Fixes: 0db4f9b91c86 ("tty: serial: imx: enable imx serial console port as module") Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Link: https://patch.msgid.link/20260110232643.3533351-2-rdunlap@infradead.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 79527d86ba91c2d9354832d19fd12b3baa66bd10 ]

SERIAL_IMX_CONSOLE is a build option for the imx driver (SERIAL_IMX).
It does not build a separate console driver file, so it can't be built
as a module since it isn't built at all.

Change the Kconfig symbol from tristate to bool and update the help
text accordingly.

Fixes: 0db4f9b91c86 ("tty: serial: imx: enable imx serial console port as module")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Link: https://patch.msgid.link/20260110232643.3533351-2-rdunlap@infradead.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
serial: sprd: Return -EPROBE_DEFER when uart clock is not ready 2026-01-19T12:11:47+00:00 Wenhua Lin Wenhua.Lin@unisoc.com 2025-10-22T03:08:40+00:00 5422ff46ccb6addf9365605f5608d5a1d4a8730a [ Upstream commit 29e8a0c587e328ed458380a45d6028adf64d7487 ] In sprd_clk_init(), when devm_clk_get() returns -EPROBE_DEFER for either uart or source clock, we should propagate the error instead of just warning and continuing with NULL clocks. Currently the driver only emits a warning when clock acquisition fails and proceeds with NULL clock pointers. This can lead to issues later when the clocks are actually needed. More importantly, when the clock provider is not ready yet and returns -EPROBE_DEFER, we should return this error to allow deferred probing. This change adds explicit checks for -EPROBE_DEFER after both: 1. devm_clk_get(uport->dev, uart) 2. devm_clk_get(uport->dev, source) When -EPROBE_DEFER is encountered, the function now returns -EPROBE_DEFER to let the driver framework retry probing later when the clock dependencies are resolved. Signed-off-by: Wenhua Lin <Wenhua.Lin@unisoc.com> Link: https://patch.msgid.link/20251022030840.956589-1-Wenhua.Lin@unisoc.com Reviewed-by: Cixi Geng <cixi.geng@linux.dev> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 29e8a0c587e328ed458380a45d6028adf64d7487 ]

In sprd_clk_init(), when devm_clk_get() returns -EPROBE_DEFER
for either uart or source clock, we should propagate the
error instead of just warning and continuing with NULL clocks.

Currently the driver only emits a warning when clock acquisition
fails and proceeds with NULL clock pointers. This can lead to
issues later when the clocks are actually needed. More importantly,
when the clock provider is not ready yet and returns -EPROBE_DEFER,
we should return this error to allow deferred probing.

This change adds explicit checks for -EPROBE_DEFER after both:
1. devm_clk_get(uport->dev, uart)
2. devm_clk_get(uport->dev, source)

When -EPROBE_DEFER is encountered, the function now returns
-EPROBE_DEFER to let the driver framework retry probing
later when the clock dependencies are resolved.

Signed-off-by: Wenhua Lin <Wenhua.Lin@unisoc.com>
Link: https://patch.msgid.link/20251022030840.956589-1-Wenhua.Lin@unisoc.com
Reviewed-by: Cixi Geng <cixi.geng@linux.dev>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
serial: add support of CPCI cards 2026-01-19T12:11:25+00:00 Magne Bruno magne.bruno@addi-data.com 2025-11-10T16:24:56+00:00 cdfd14f001d3fb4baf802267d102af355944b4f9 commit 0e5a99e0e5f50353b86939ff6e424800d769c818 upstream. Addi-Data GmbH is manufacturing multi-serial ports cards supporting CompactPCI (known as CPCI). Those cards are identified with different DeviceIds. Those cards integrating standard UARTs work the same way as PCI/PCIe models already supported in the serial driver. Signed-off-by: Magne Bruno <magne.bruno@addi-data.com> Link: https://patch.msgid.link/20251110162456.341029-1-magne.bruno@addi-data.com Cc: stable <stable@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 0e5a99e0e5f50353b86939ff6e424800d769c818 upstream.

Addi-Data GmbH is manufacturing multi-serial ports cards supporting CompactPCI (known as CPCI).
Those cards are identified with different DeviceIds. Those cards integrating standard UARTs
work the same way as PCI/PCIe models already supported in the serial driver.

Signed-off-by: Magne Bruno <magne.bruno@addi-data.com>
Link: https://patch.msgid.link/20251110162456.341029-1-magne.bruno@addi-data.com
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
serial: amba-pl011: prefer dma_mapping_error() over explicit address checking 2025-12-06T21:08:23+00:00 Miaoqian Lin linmq006@gmail.com 2025-10-27T09:20:50+00:00 16336cc676a5d49eeb231644f61ce7c7850addc2 commit eb4917f557d43c7a1c805dd73ffcdfddb2aba39a upstream. Check for returned DMA addresses using specialized dma_mapping_error() helper which is generally recommended for this purpose by Documentation/core-api/dma-api.rst: "In some circumstances dma_map_single(), ... will fail to create a mapping. A driver can check for these errors by testing the returned DMA address with dma_mapping_error()." Found via static analysis and this is similar to commit fa0308134d26 ("ALSA: memalloc: prefer dma_mapping_error() over explicit address checking") Fixes: 58ac1b379979 ("ARM: PL011: Fix DMA support") Cc: stable <stable@kernel.org> Signed-off-by: Miaoqian Lin <linmq006@gmail.com> Reviewed-by: Gregory CLEMENT <gregory.clement@bootlin.com> Link: https://patch.msgid.link/20251027092053.87937-1-linmq006@gmail.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit eb4917f557d43c7a1c805dd73ffcdfddb2aba39a upstream.

Check for returned DMA addresses using specialized dma_mapping_error()
helper which is generally recommended for this purpose by
Documentation/core-api/dma-api.rst:

  "In some circumstances dma_map_single(), ...
will fail to create a mapping. A driver can check for these errors
by testing the returned DMA address with dma_mapping_error()."

Found via static analysis and this is similar to commit fa0308134d26
("ALSA: memalloc: prefer dma_mapping_error() over explicit address checking")

Fixes: 58ac1b379979 ("ARM: PL011: Fix DMA support")
Cc: stable <stable@kernel.org>
Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
Reviewed-by: Gregory CLEMENT <gregory.clement@bootlin.com>
Link: https://patch.msgid.link/20251027092053.87937-1-linmq006@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>