Hi Andy, Thank you for your patches. See inline comment below. On Thu, 8 Feb 2024 20:48:08 +0200 Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> wrote: > There is a driver that uses small buffer for the string, when we > add a new one, we may avoid duplication and use one provided by > the line display library. Allow user to skip buffer pointer when > registering a device. > > Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> > --- > drivers/auxdisplay/line-display.c | 4 ++-- > drivers/auxdisplay/line-display.h | 4 ++++ > 2 files changed, 6 insertions(+), 2 deletions(-) > > diff --git a/drivers/auxdisplay/line-display.c b/drivers/auxdisplay/line-display.c > index da47fc59f6cb..a3c706e1739d 100644 > --- a/drivers/auxdisplay/line-display.c > +++ b/drivers/auxdisplay/line-display.c > @@ -330,8 +330,8 @@ int linedisp_register(struct linedisp *linedisp, struct device *parent, > linedisp->dev.parent = parent; > linedisp->dev.type = &linedisp_type; > linedisp->ops = ops; > - linedisp->buf = buf; > - linedisp->num_chars = num_chars; > + linedisp->buf = buf ? buf : linedisp->curr; > + linedisp->num_chars = buf ? num_chars : min(num_chars, LINEDISP_DEFAULT_BUF_SZ); It's not a big buffer, but now it's always there even if it's not used. And even if it's used, it might be only partially used. Why not used a malloc instead? > linedisp->scroll_rate = DEFAULT_SCROLL_RATE; > > err = ida_alloc(&linedisp_id, GFP_KERNEL); > diff --git a/drivers/auxdisplay/line-display.h b/drivers/auxdisplay/line-display.h > index 65d782111f53..4c354b8f376e 100644 > --- a/drivers/auxdisplay/line-display.h > +++ b/drivers/auxdisplay/line-display.h > @@ -54,12 +54,15 @@ struct linedisp_ops { > void (*update)(struct linedisp *linedisp); > }; > > +#define LINEDISP_DEFAULT_BUF_SZ 8u > + > /** > * struct linedisp - character line display private data structure > * @dev: the line display device > * @id: instance id of this display > * @timer: timer used to implement scrolling > * @ops: character line display operations > + * @curr: fallback buffer for the string > * @buf: pointer to the buffer for the string currently displayed > * @message: the full message to display or scroll on the display > * @num_chars: the number of characters that can be displayed > @@ -73,6 +76,7 @@ struct linedisp { > struct timer_list timer; > const struct linedisp_ops *ops; > struct linedisp_map *map; > + char curr[LINEDISP_DEFAULT_BUF_SZ]; > char *buf; > char *message; > unsigned int num_chars;