linux.git/drivers/tty/serial/xilinx_uartps.c, branch v5.13 Linux kernel source tree serial: xilinx_uartps: drop low-latency workaround 2021-04-22T10:09:26+00:00 Johan Hovold johan@kernel.org 2021-04-21T09:55:09+00:00 348fbd61700ce0527625582aee8bb136373f10af Commit c8dbdc842d30 ("serial: xuartps: Rewrite the interrupt handling logic") reworked the driver interrupt processing but also, without comment, added an unnecessary workaround for the infamous low_latency behaviour of tty_flip_buffer_push() which had been removed years before. Specifically, since commit a9c3f68f3cd8 ("tty: Fix low_latency BUG"), tty_flip_buffer_push() always schedules a work item to push data to the line discipline and there's no need to keep any low_latency hacks around. Cc: Michal Simek <michal.simek@xilinx.com> Signed-off-by: Johan Hovold <johan@kernel.org> Link: https://lore.kernel.org/r/20210421095509.3024-27-johan@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
Commit c8dbdc842d30 ("serial: xuartps: Rewrite the interrupt handling
logic") reworked the driver interrupt processing but also, without
comment, added an unnecessary workaround for the infamous low_latency
behaviour of tty_flip_buffer_push() which had been removed years
before.

Specifically, since commit a9c3f68f3cd8 ("tty: Fix low_latency BUG"),
tty_flip_buffer_push() always schedules a work item to push data to the
line discipline and there's no need to keep any low_latency hacks around.

Cc: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210421095509.3024-27-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tty: serial: xilinx_uartps: Supply description for missing member 'cts_override' 2020-11-06T09:54:05+00:00 Lee Jones lee.jones@linaro.org 2020-11-04T19:35:35+00:00 b482bd793c55a1a40c5ec5ab20bc7b8ee20ff6c4 Fixes the following W=1 kernel build warning(s): drivers/tty/serial/xilinx_uartps.c:205: warning: Function parameter or member 'cts_override' not described in 'cdns_uart' Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Jiri Slaby <jirislaby@kernel.org> Cc: Michal Simek <michal.simek@xilinx.com> Cc: linux-serial@vger.kernel.org Signed-off-by: Lee Jones <lee.jones@linaro.org> Link: https://lore.kernel.org/r/20201104193549.4026187-23-lee.jones@linaro.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
Fixes the following W=1 kernel build warning(s):

 drivers/tty/serial/xilinx_uartps.c:205: warning: Function parameter or member 'cts_override' not described in 'cdns_uart'

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jirislaby@kernel.org>
Cc: Michal Simek <michal.simek@xilinx.com>
Cc: linux-serial@vger.kernel.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20201104193549.4026187-23-lee.jones@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
treewide: Use fallthrough pseudo-keyword 2020-08-23T22:36:59+00:00 Gustavo A. R. Silva gustavoars@kernel.org 2020-08-23T22:36:59+00:00 df561f6688fef775baa341a0f5d960becd248b11 Replace the existing /* fall through */ comments and its variants with the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary fall-through markings when it is the case. [1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> 
Replace the existing /* fall through */ comments and its variants with
the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary
fall-through markings when it is the case.

[1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
tty: xilinx_uartps: Really fix id assignment 2020-07-21T16:12:03+00:00 Helmut Grohne helmut.grohne@intenta.de 2020-07-13T07:32:28+00:00 22a82fa7d6c3e16d56a036b1fa697a39b954adf0 The problems started with the revert (18cc7ac8a28e28). The cdns_uart_console.index is statically assigned -1. When the port is registered, Linux assigns consecutive numbers to it. It turned out that when using ttyPS1 as console, the index is not updated as we are reusing the same cdns_uart_console instance for multiple ports. When registering ttyPS0, it gets updated from -1 to 0, but when registering ttyPS1, it already is 0 and not updated. That led to 2ae11c46d5fdc4. It assigns the index prior to registering the uart_driver once. Unfortunately, that ended up breaking the situation where the probe order does not match the id order. When using the same device tree for both uboot and linux, it is important that the serial0 alias points to the console. So some boards reverse those aliases. This was reported by Jan Kiszka. The proposed fix was reverting the index assignment and going back to the previous iteration. However such a reversed assignement (serial0 -> uart1, serial1 -> uart0) was already partially broken by the revert (18cc7ac8a28e28). While the ttyPS device works, the kmsg connection is already broken and kernel messages go missing. Reverting the id assignment does not fix this. >From the xilinx_uartps driver pov (after reverting the refactoring commits), there can be only one console. This manifests in static variables console_pprt and cdns_uart_console. These variables are not properly linked and can go out of sync. The cdns_uart_console.index is important for uart_add_one_port. We call that function for each port - one of which hopefully is the console. If it isn't, the CON_ENABLED flag is not set and console_port is cleared. The next cdns_uart_probe call then tries to register the next port using that same cdns_uart_console. It is important that console_port and cdns_uart_console (and its index in particular) stay in sync. The index assignment implemented by Shubhrajyoti Datta is correct in principle. It just may have to happen a second time if the first cdns_uart_probe call didn't encounter the console device. And we shouldn't change the index once the console uart is registered. Reported-by: Shubhrajyoti Datta <shubhrajyoti.datta@xilinx.com> Reported-by: Jan Kiszka <jan.kiszka@web.de> Link: https://lore.kernel.org/linux-serial/f4092727-d8f5-5f91-2c9f-76643aace993@siemens.com/ Fixes: 18cc7ac8a28e28 ("Revert "serial: uartps: Register own uart console and driver structures"") Fixes: 2ae11c46d5fdc4 ("tty: xilinx_uartps: Fix missing id assignment to the console") Fixes: 76ed2e10579671 ("Revert "tty: xilinx_uartps: Fix missing id assignment to the console"") Signed-off-by: Helmut Grohne <helmut.grohne@intenta.de> Cc: stable <stable@vger.kernel.org> Link: https://lore.kernel.org/r/20200713073227.GA3805@laureti-dev Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
The problems started with the revert (18cc7ac8a28e28). The
cdns_uart_console.index is statically assigned -1. When the port is
registered, Linux assigns consecutive numbers to it. It turned out that
when using ttyPS1 as console, the index is not updated as we are reusing
the same cdns_uart_console instance for multiple ports. When registering
ttyPS0, it gets updated from -1 to 0, but when registering ttyPS1, it
already is 0 and not updated.

That led to 2ae11c46d5fdc4. It assigns the index prior to registering
the uart_driver once. Unfortunately, that ended up breaking the
situation where the probe order does not match the id order. When using
the same device tree for both uboot and linux, it is important that the
serial0 alias points to the console. So some boards reverse those
aliases. This was reported by Jan Kiszka. The proposed fix was reverting
the index assignment and going back to the previous iteration.

However such a reversed assignement (serial0 -> uart1, serial1 -> uart0)
was already partially broken by the revert (18cc7ac8a28e28). While the
ttyPS device works, the kmsg connection is already broken and kernel
messages go missing. Reverting the id assignment does not fix this.

>From the xilinx_uartps driver pov (after reverting the refactoring
commits), there can be only one console. This manifests in static
variables console_pprt and cdns_uart_console. These variables are not
properly linked and can go out of sync. The cdns_uart_console.index is
important for uart_add_one_port. We call that function for each port -
one of which hopefully is the console. If it isn't, the CON_ENABLED flag
is not set and console_port is cleared. The next cdns_uart_probe call
then tries to register the next port using that same cdns_uart_console.

It is important that console_port and cdns_uart_console (and its index
in particular) stay in sync. The index assignment implemented by
Shubhrajyoti Datta is correct in principle. It just may have to happen a
second time if the first cdns_uart_probe call didn't encounter the
console device. And we shouldn't change the index once the console uart
is registered.

Reported-by: Shubhrajyoti Datta <shubhrajyoti.datta@xilinx.com>
Reported-by: Jan Kiszka <jan.kiszka@web.de>
Link: https://lore.kernel.org/linux-serial/f4092727-d8f5-5f91-2c9f-76643aace993@siemens.com/
Fixes: 18cc7ac8a28e28 ("Revert "serial: uartps: Register own uart console and driver structures"")
Fixes: 2ae11c46d5fdc4 ("tty: xilinx_uartps: Fix missing id assignment to the console")
Fixes: 76ed2e10579671 ("Revert "tty: xilinx_uartps: Fix missing id assignment to the console"")
Signed-off-by: Helmut Grohne <helmut.grohne@intenta.de>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20200713073227.GA3805@laureti-dev
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Revert "tty: xilinx_uartps: Fix missing id assignment to the console" 2020-06-27T14:16:37+00:00 Jan Kiszka jan.kiszka@siemens.com 2020-06-18T08:11:40+00:00 76ed2e105796710cf5b8a4ba43c81eceed948b70 This reverts commit 2ae11c46d5fdc46cb396e35911c713d271056d35. It turned out to break the ultra96-rev1, e.g., which uses uart1 as serial0 (and stdout-path = "serial0:115200n8"). Fixes: 2ae11c46d5fd ("tty: xilinx_uartps: Fix missing id assignment to the console") Cc: stable <stable@vger.kernel.org> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> Reviewed-by: Michal Simek <michal.simek@xilinx.com> Tested-by: Michal Simek <michal.simek@xilinx.com> Link: https://lore.kernel.org/r/f4092727-d8f5-5f91-2c9f-76643aace993@siemens.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
This reverts commit 2ae11c46d5fdc46cb396e35911c713d271056d35.

It turned out to break the ultra96-rev1, e.g., which uses uart1 as
serial0 (and stdout-path = "serial0:115200n8").

Fixes: 2ae11c46d5fd ("tty: xilinx_uartps: Fix missing id assignment to the console")
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Reviewed-by: Michal Simek <michal.simek@xilinx.com>
Tested-by: Michal Simek <michal.simek@xilinx.com>
Link: https://lore.kernel.org/r/f4092727-d8f5-5f91-2c9f-76643aace993@siemens.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Merge 5.7-rc5 into tty-next 2020-05-11T06:55:10+00:00 Greg Kroah-Hartman gregkh@linuxfoundation.org 2020-05-11T06:55:10+00:00 1cc18584e5acfd845464616b66fb2fd81eff467e We need the tty fixes in here too. Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
We need the tty fixes in here too.

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tty: xilinx_uartps: Fix missing id assignment to the console 2020-05-04T16:55:45+00:00 Shubhrajyoti Datta shubhrajyoti.datta@xilinx.com 2020-05-04T14:27:28+00:00 2ae11c46d5fdc46cb396e35911c713d271056d35 When serial console has been assigned to ttyPS1 (which is serial1 alias) console index is not updated property and pointing to index -1 (statically initialized) which ends up in situation where nothing has been printed on the port. The commit 18cc7ac8a28e ("Revert "serial: uartps: Register own uart console and driver structures"") didn't contain this line which was removed by accident. Fixes: 18cc7ac8a28e ("Revert "serial: uartps: Register own uart console and driver structures"") Signed-off-by: Shubhrajyoti Datta <shubhrajyoti.datta@xilinx.com> Cc: stable <stable@vger.kernel.org> Signed-off-by: Michal Simek <michal.simek@xilinx.com> Link: https://lore.kernel.org/r/ed3111533ef5bd342ee5ec504812240b870f0853.1588602446.git.michal.simek@xilinx.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
When serial console has been assigned to ttyPS1 (which is serial1 alias)
console index is not updated property and pointing to index -1 (statically
initialized) which ends up in situation where nothing has been printed on
the port.

The commit 18cc7ac8a28e ("Revert "serial: uartps: Register own uart console
and driver structures"") didn't contain this line which was removed by
accident.

Fixes: 18cc7ac8a28e ("Revert "serial: uartps: Register own uart console and driver structures"")
Signed-off-by: Shubhrajyoti Datta <shubhrajyoti.datta@xilinx.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Link: https://lore.kernel.org/r/ed3111533ef5bd342ee5ec504812240b870f0853.1588602446.git.michal.simek@xilinx.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Merge 5.7-rc3 into tty-next 2020-04-27T07:33:21+00:00 Greg Kroah-Hartman gregkh@linuxfoundation.org 2020-04-27T07:33:21+00:00 e947861d0ccbc765af4512a395251e6af6857600 We need the tty/serial fixes in here too. Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
We need the tty/serial fixes in here too.

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
serial: uartps: Use cdns_uart_tx_empty in console_write 2020-04-16T14:15:14+00:00 Raviteja Narayanam raviteja.narayanam@xilinx.com 2020-04-09T06:26:03+00:00 a8e7346b7c0a3b33963e5e043e2c612fdf69de34 Instead of accessing the registers and checking for tx_empty, use cdns_uart_tx_empty in cdns_uart_console_write function. Signed-off-by: Raviteja Narayanam <raviteja.narayanam@xilinx.com> Reviewed-by: Shubhrajyoti Datta <shubhrajyoti.datta@xilinx.com> Link: https://lore.kernel.org/r/1586413563-29125-3-git-send-email-raviteja.narayanam@xilinx.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
Instead of accessing the registers and checking for tx_empty,
use cdns_uart_tx_empty in cdns_uart_console_write function.

Signed-off-by: Raviteja Narayanam <raviteja.narayanam@xilinx.com>
Reviewed-by: Shubhrajyoti Datta <shubhrajyoti.datta@xilinx.com>
Link: https://lore.kernel.org/r/1586413563-29125-3-git-send-email-raviteja.narayanam@xilinx.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
serial: uartps: Wait for tx_empty in console setup 2020-04-16T14:15:14+00:00 Raviteja Narayanam raviteja.narayanam@xilinx.com 2020-04-09T06:26:02+00:00 42e11948ddf68b9f799cad8c0ddeab0a39da33e8 On some platforms, the log is corrupted while console is being registered. It is observed that when set_termios is called, there are still some bytes in the FIFO to be transmitted. So, wait for tx_empty inside cdns_uart_console_setup before calling set_termios. Signed-off-by: Raviteja Narayanam <raviteja.narayanam@xilinx.com> Reviewed-by: Shubhrajyoti Datta <shubhrajyoti.datta@xilinx.com> Link: https://lore.kernel.org/r/1586413563-29125-2-git-send-email-raviteja.narayanam@xilinx.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
On some platforms, the log is corrupted while console is being
registered. It is observed that when set_termios is called, there
are still some bytes in the FIFO to be transmitted.

So, wait for tx_empty inside cdns_uart_console_setup before calling
set_termios.

Signed-off-by: Raviteja Narayanam <raviteja.narayanam@xilinx.com>
Reviewed-by: Shubhrajyoti Datta <shubhrajyoti.datta@xilinx.com>
Link: https://lore.kernel.org/r/1586413563-29125-2-git-send-email-raviteja.narayanam@xilinx.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>