kernel/linux.git/drivers/tty/tty_port.c, branch v6.1.174

tty: fix tty_port_tty_*hangup() kernel-doc

2026-01-11T14:19:26+00:00

commit 6241b49540a65a6d5274fa938fd3eb4cbfe2e076 upstream. The commit below added a new helper, but omitted to move (and add) the corressponding kernel-doc. Do it now. Signed-off-by: "Jiri Slaby (SUSE)" Fixes: 2b5eac0f8c6e ("tty: introduce and use tty_port_tty_vhangup() helper") Link: https://lore.kernel.org/all/b23d566c-09dc-7374-cc87-0ad4660e8b2e@linux.intel.com/ Reported-by: Ilpo Järvinen Cc: Jonathan Corbet Cc: linux-doc@vger.kernel.org Link: https://lore.kernel.org/r/20250624080641.509959-6-jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman

tty: introduce and use tty_port_tty_vhangup() helper

2026-01-11T14:19:23+00:00

[ Upstream commit 2b5eac0f8c6e79bc152c8804f9f88d16717013ab ] This code (tty_get -> vhangup -> tty_put) is repeated on few places. Introduce a helper similar to tty_port_tty_hangup() (asynchronous) to handle even vhangup (synchronous). And use it on those places. In fact, reuse the tty_port_tty_hangup()'s code and call tty_vhangup() depending on a new bool parameter. Signed-off-by: "Jiri Slaby (SUSE)" Cc: Karsten Keil Cc: David Lin Cc: Johan Hovold Cc: Alex Elder Cc: Oliver Neukum Cc: Marcel Holtmann Cc: Johan Hedberg Cc: Luiz Augusto von Dentz Reviewed-by: Ilpo Järvinen Link: https://lore.kernel.org/r/20250611100319.186924-2-jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman Stable-dep-of: 74098cc06e75 ("xhci: dbgtty: fix device unregister: fixup") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

tty: Implement lookahead to process XON/XOFF timely

2022-06-10T11:51:31+00:00

When tty is not read from, XON/XOFF may get stuck into an intermediate buffer. As those characters are there to do software flow-control, it is not very useful. In the case where neither end reads from ttys, the receiving ends might not be able receive the XOFF characters and just keep sending more data to the opposite direction. This problem is almost guaranteed to occur with DMA which sends data in large chunks. If TTY is slow to process characters, that is, eats less than given amount in receive_buf, invoke lookahead for the rest of the chars to process potential XON/XOFF characters. We need to keep track of how many characters have been processed by the lookahead to avoid processing the flow control char again on the normal path. Bookkeeping occurs parallel on two layers (tty_buffer and n_tty) to avoid passing the lookahead_count through the whole call chain. When a flow-control char is processed, two things must occur: a) it must not be treated as normal char b) if not yet processed, flow-control actions need to be taken The return value of n_tty_receive_char_flow_ctrl() tells caller a), and b) is kept internal to n_tty_receive_char_flow_ctrl(). If characters were previous looked ahead, __receive_buf() makes two calls to the appropriate n_tty_receive_buf_* function. First call is made with lookahead_done=true for the characters that were subject to lookahead earlier and then with lookahead=false for the new characters. Either of the calls might be skipped when it has no characters to handle. Reported-by: Gilles Buloz Reviewed-by: Andy Shevchenko Signed-off-by: Ilpo Järvinen Link: https://lore.kernel.org/r/20220606153652.63554-2-ilpo.jarvinen@linux.intel.com Signed-off-by: Greg Kroah-Hartman

tty: Drop duplicate NULL check in TTY port functions

2022-02-04T15:58:25+00:00

The free_page(addr), which becomes free_pages(addr, 0) checks addr against 0. No need to repeat this check in the callers, i.e. tty_port_free_xmit_buf() and tty_port_destructor(). Note, INIT_KFIFO() is safe without that check, because it operates on a separate member and doesn't rely on the FIFO itself to be allocated. Acked-by: Jiri Slaby Signed-off-by: Andy Shevchenko Link: https://lore.kernel.org/r/20220204153253.11006-1-andriy.shevchenko@linux.intel.com Signed-off-by: Greg Kroah-Hartman

tty: tty_port_open, document shutdown vs failed activate

2022-01-26T13:54:48+00:00

Add a note that ->shutdown is not called when ->activate fails. Just so we are clear. Signed-off-by: Jiri Slaby Link: https://lore.kernel.org/r/20220124071430.14907-5-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman

tty: add kfifo to tty_port

2022-01-26T13:54:48+00:00

Define a kfifo inside struct tty_port. We use DECLARE_KFIFO_PTR and let the preexisting tty_port::xmit_buf be also the buffer for the kfifo. And handle the initialization/decomissioning along with xmit_buf, i.e. in tty_port_alloc_xmit_buf() and tty_port_free_xmit_buf(), respectively. This allows for kfifo use in drivers which opt-in, while others still may use the old xmit_buf. mxser will be the first user in the next few patches. Signed-off-by: Jiri Slaby Link: https://lore.kernel.org/r/20220124071430.14907-4-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman

tty: add kernel-doc for more tty_port functions

2021-11-26T15:27:43+00:00

From the main tty_port functions, only tty_port_destroy() was documented. Document more of them, so that we can reference them in Documentation/ later in this series. Signed-off-by: Jiri Slaby Link: https://lore.kernel.org/r/20211126081611.11001-19-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman

tty: reformat kernel-doc in tty_port.c

2021-11-26T15:27:42+00:00

Kernel-doc is a bit strict about some formatting. So fix these: 1) When there is a tab in comments, it thinks the line is a continuation one. So the description of the functions end up as descriptions of the last parameter described. Remove the tabs. 2) Remove newlines before parameters description. This was not wrong per se, only inconsistent with the rest of the file. 3) Add periods to the end of sentences where appropriate. 4) Use recognized "Note" instead of "NB" (nota bene). 5) Add "()" to function names and "%" to constants, so that they are properly highlighted. By the above, this patch also unifies these docs with the other kernel-doc's in this file. Signed-off-by: Jiri Slaby Link: https://lore.kernel.org/r/20211126081611.11001-12-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman

tty: tty_port: Fix coding style issues of block comments

2021-05-13T16:29:13+00:00

Fix coding style issues of block comments, reported by checkpatch.pl. Besides, add a period at the end of the sentenses. Signed-off-by: Xiaofei Tan Link: https://lore.kernel.org/r/1620811585-18582-18-git-send-email-tanxiaofei@huawei.com Signed-off-by: Greg Kroah-Hartman

tty: tty_port: Add a blank line after declarations

2021-05-13T16:29:13+00:00

Add a blank line after declarations, reported by checkpatch.pl. Signed-off-by: Xiaofei Tan Link: https://lore.kernel.org/r/1620811585-18582-17-git-send-email-tanxiaofei@huawei.com Signed-off-by: Greg Kroah-Hartman