linux.git/drivers/tty/serial/pch_uart.c, branch v6.1 Linux kernel source tree serial: pch_uart: CIRC_CNT_TO_END() is enough 2022-08-30T12:23:05+00:00 Ilpo Järvinen ilpo.jarvinen@linux.intel.com 2022-08-23T14:18:39+00:00 1a9a59104646417ef2d71a7dcfc5243672c9d8e6 Testing also CIRC_CNT() with CIRC_CNT_TO_END() is unnecessary because to latter alone covers all necessary cases. Reviewed-by: Jiri Slaby <jirislaby@kernel.org> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Link: https://lore.kernel.org/r/20220823141839.165244-3-ilpo.jarvinen@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
Testing also CIRC_CNT() with CIRC_CNT_TO_END() is unnecessary because
to latter alone covers all necessary cases.

Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20220823141839.165244-3-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
serial: Make ->set_termios() old ktermios const 2022-08-30T12:22:35+00:00 Ilpo Järvinen ilpo.jarvinen@linux.intel.com 2022-08-16T11:57:37+00:00 bec5b814d46c2a704c3c8148752e62a33e9fa6dc There should be no reason to adjust old ktermios which is going to get discarded anyway. Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Link: https://lore.kernel.org/r/20220816115739.10928-7-ilpo.jarvinen@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
There should be no reason to adjust old ktermios which is going to get
discarded anyway.

Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20220816115739.10928-7-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
serial: Consolidate BOTH_EMPTY use 2022-06-27T12:41:31+00:00 Ilpo Järvinen ilpo.jarvinen@linux.intel.com 2022-06-24T20:54:24+00:00 34619de1b8cb52afa90bbeb3b4fbad34c28f19cf Per file BOTH_EMPTY defines are littering our source code here and there. Define once in serial.h and create helper for the check too. Reviewed-by: Jiri Slaby <jirislaby@kernel.org> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Link: https://lore.kernel.org/r/20220624205424.12686-7-ilpo.jarvinen@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
Per file BOTH_EMPTY defines are littering our source code here and
there. Define once in serial.h and create helper for the check
too.

Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20220624205424.12686-7-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
serial: pch: inline pop_tx() into handle_tx() 2022-05-05T20:42:47+00:00 Jiri Slaby jslaby@suse.cz 2022-05-03T08:08:08+00:00 240754894c30e3b13ca91113f177dd7f315eb297 Given pop_tx() is a simple loop, inline it directly into handle_tx(). The code in handle_tx() looks much saner and straightforward now. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20220503080808.28332-6-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
Given pop_tx() is a simple loop, inline it directly into handle_tx().

The code in handle_tx() looks much saner and straightforward now.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220503080808.28332-6-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
serial: pch: simplify pop_tx() even more 2022-05-05T20:42:47+00:00 Jiri Slaby jslaby@suse.cz 2022-05-03T08:08:07+00:00 80219e59ff503f2ba7d87b9fda40c69e5ff71546 1) take uart_tx_stopped into account every loop (the same as other uart drivers) 2) no need for 'count' variable, operate on 'size' directly This allows inlining this into handle_tx() nicely in the next patch. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20220503080808.28332-5-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
1) take uart_tx_stopped into account every loop (the same as other uart
   drivers)
2) no need for 'count' variable, operate on 'size' directly

This allows inlining this into handle_tx() nicely in the next patch.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220503080808.28332-5-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
serial: pch: remove xmit circ_buf size double check 2022-05-05T20:42:46+00:00 Jiri Slaby jslaby@suse.cz 2022-05-03T08:08:06+00:00 862526523e71a96e11ae48e081c424fdb1b50011 One is in handle_tx() (as "min(xmit->head - xmit->tail, fifo_size))", another one in pop_tx() (as uart_circ_empty(xmit)). So keep only the latter. This makes the code simpler and size variable is not needed now. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20220503080808.28332-4-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
One is in handle_tx() (as "min(xmit->head - xmit->tail, fifo_size))",
another one in pop_tx() (as uart_circ_empty(xmit)). So keep only the
latter.

This makes the code simpler and size variable is not needed now.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220503080808.28332-4-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
serial: pch: remove debug print from pop_tx 2022-05-05T20:42:46+00:00 Jiri Slaby jslaby@suse.cz 2022-05-03T08:08:05+00:00 9bc995f51d7828bec9b7432f0034b6e31cefb851 It makes the code overly complicated for no good reason. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20220503080808.28332-3-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
It makes the code overly complicated for no good reason.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220503080808.28332-3-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
serial: pch: decomission pch_uart_hal_write() 2022-05-05T20:42:46+00:00 Jiri Slaby jslaby@suse.cz 2022-05-03T08:08:04+00:00 fcfb1c3982b9c80d62c94aba2107acd4cb00cc5f It's horrid and if we inline it into callers, we can get rid of a lot of sugar around. So: * x_char handling becomes a single iowrite8. * xmit->buf handling is a single loop simply writing characters one by one directly from the buf instead of complex cnt_to_end computations. Until the buf is empty or fifo size is reached. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20220503080808.28332-2-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
It's horrid and if we inline it into callers, we can get rid of a lot of
sugar around.

So:
* x_char handling becomes a single iowrite8.
* xmit->buf handling is a single loop simply writing characters one by
  one directly from the buf instead of complex cnt_to_end computations.
  Until the buf is empty or fifo size is reached.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220503080808.28332-2-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
serial: pch: don't overwrite xmit->buf[0] by x_char 2022-05-05T20:42:45+00:00 Jiri Slaby jslaby@suse.cz 2022-05-03T08:08:03+00:00 d9f3af4fbb1d955bbaf872d9e76502f6e3e803cb When x_char is to be sent, the TX path overwrites whatever is in the circular buffer at offset 0 with x_char and sends it using pch_uart_hal_write(). I don't understand how this was supposed to work if xmit->buf[0] already contained some character. It must have been lost. Remove this whole pop_tx_x() concept and do the work directly in the callers. (Without printing anything using dev_dbg().) Cc: <stable@vger.kernel.org> Fixes: 3c6a483275f4 (Serial: EG20T: add PCH_UART driver) Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20220503080808.28332-1-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
When x_char is to be sent, the TX path overwrites whatever is in the
circular buffer at offset 0 with x_char and sends it using
pch_uart_hal_write(). I don't understand how this was supposed to work
if xmit->buf[0] already contained some character. It must have been
lost.

Remove this whole pop_tx_x() concept and do the work directly in the
callers. (Without printing anything using dev_dbg().)

Cc: <stable@vger.kernel.org>
Fixes: 3c6a483275f4 (Serial: EG20T: add PCH_UART driver)
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220503080808.28332-1-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
serial: pch: move size check from pop_tx one level up 2022-05-05T20:42:45+00:00 Jiri Slaby jslaby@suse.cz 2022-05-03T08:06:07+00:00 6c1f77c3781a893cabe04b560a63b0524fe458f3 'count' is zero in the pop_tx()'s comparison against 'size'. So the 'if' tries to find out if 'size' is negative or zero and returns in that case. But it cannot be negative, due to previous (size < 0) check in the caller: handle_tx(). So simply move this check from pop_tx() to handle_tx(). Now it's clear that pop_tx() is called only if fifo_size is non-zero. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20220503080613.27601-2-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
'count' is zero in the pop_tx()'s comparison against 'size'. So the 'if'
tries to find out if 'size' is negative or zero and returns in that
case. But it cannot be negative, due to previous (size < 0) check in the
caller: handle_tx().

So simply move this check from pop_tx() to handle_tx(). Now it's clear
that pop_tx() is called only if fifo_size is non-zero.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220503080613.27601-2-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>