kernel/linux.git/drivers/auxdisplay/charlcd.c, branch v6.3

auxdisplay: charlcd: checking for pointer reference before dereferencing

2021-11-24T10:46:52+00:00

Check if the pointer lcd->ops->init_display exists before dereferencing it. If a driver called charlcd_init() without defining the ops, this would return segmentation fault, as happened to me when implementing a charlcd driver. Checking the pointer before dereferencing protects from segmentation fault. Signed-off-by: Luiz Sampaio Signed-off-by: Miguel Ojeda

auxdisplay: charlcd: fixing coding style issue

2021-11-24T10:46:42+00:00

Removing 'int' from 'unsigned long int' declaration, which is unnecessary. Signed-off-by: Luiz Sampaio Signed-off-by: Miguel Ojeda

auxdisplay: charlcd: Drop unneeded initializers and switch to C99 style

2021-07-16T05:42:35+00:00

For structure initializers the fields are 0 (or NULL) by default, so there is no need to fill them explicitly. Besides that, much easier to read when initializers use C99 style. Hence, convert to C99 style as well. Signed-off-by: Andy Shevchenko Acked-by: Willy Tarreau Signed-off-by: Miguel Ojeda

auxdisplay: Remove in_interrupt() usage.

2021-03-16T15:32:40+00:00

charlcd_write() is invoked as a VFS->write() callback and as such it is always invoked from preemptible context and may sleep. charlcd_puts() is invoked from register/unregister callback which is preemptible. The reboot notifier callback is also invoked from preemptible context. Therefore there is no need to use in_interrupt() to figure out if it is safe to sleep because it always is. in_interrupt() and related context checks are being removed from non-core code. Using schedule() to schedule (and be friendly to others) is discouraged and cond_resched() should be used instead. Remove in_interrupt() and use cond_resched() to schedule every 32 iterations if needed. Link: https://lkml.kernel.org/r/20200914204209.256266093@linutronix.de Signed-off-by: Sebastian Andrzej Siewior [mo: fixed a couple typos in comment and commit message] Signed-off-by: Miguel Ojeda

auxdisplay: charlcd: Do not print chars at end of line

2020-11-04T10:04:05+00:00

Skip printing characters at the end of a display line. This fits to the behaviour we already had, that the cursor is nailed to the last position of a line. This might slightly change behaviour. On hd44780 displays with one or two lines the previous implementation did still write characters to the buffer of the display even if they are currently not visible. The shift_display command could be used to set the "viewing window" to a new position in the buffer and then you could see the characters previously written. This described behaviour does not work for hd44780 displays with more than two display lines. There simply is not enough buffer. So the behaviour was a bit inconsistent across different displays. The new behaviour is to stop writing characters at the end of a visible line, even if there would be room in the buffer. This allows us to have an easy implementation, that should behave equal on all supported displays. This is not hd44780 hardware dependent anymore. Reviewed-by: Willy Tarreau Signed-off-by: Lars Poeschel Signed-off-by: Miguel Ojeda

auxdisplay: Change gotoxy calling interface

2020-11-04T10:04:04+00:00

Change the calling interface for gotoxy from supplying the x and y coordinates in the charlcd struct to explicitly supplying x and y in the function arguments. This is more intuitive and allows for moving the cursor to positions independent from the position saved in the charlcd struct. Reviewed-by: Willy Tarreau Signed-off-by: Lars Poeschel Signed-off-by: Miguel Ojeda

auxdisplay: charlcd: replace last device specific stuff

2020-11-04T10:04:04+00:00

These are the last bits left in charlcd.c that are device specific and they are removed now. In detail this is: * bwidth, which is the width of the display buffer per line. This is replaced by width of the display. * hwidth, which is the size of the display buffer as a whole. This is replaced by looping all chars of a line by all lines. * the hd44780_common header include can go away. Reviewed-by: Willy Tarreau Signed-off-by: Lars Poeschel Signed-off-by: Miguel Ojeda

auxdisplay: hd44780: Remove clear_fast

2020-11-04T10:04:04+00:00

We remove the hd44780_clear_fast (display) clear implementation. With the new timeout the normal clear_display is reasonably fast. So there is no need for a clear_fast anymore. Link: https://lore.kernel.org/lkml/20200922092121.GG16421@1wt.eu/ Signed-off-by: Lars Poeschel Signed-off-by: Miguel Ojeda

auxdisplay: Call charlcd_backlight in place

2020-11-04T10:04:04+00:00

This moves the call to charlcd_backlight from the end of the switch into the actual case statement that originates the change of the backlight. This is more consistent to what is now found in this switch. Reviewed-by: Willy Tarreau Signed-off-by: Lars Poeschel Signed-off-by: Miguel Ojeda

auxdisplay: Move char redefine code to hd44780_common

2020-11-04T10:04:04+00:00

Take the code to redefine characters out of charlcd and move it to hd44780_common, as this is hd44780 specific. There is now a function hd44780_common_redefine_char that drivers use and charlcd calls it through its ops function pointer. Reviewed-by: Willy Tarreau Signed-off-by: Lars Poeschel Signed-off-by: Miguel Ojeda