comedi: ni_pcidio: Do not bother filling buffer with 0xaa byte values

On buffer change, the driver informs the mite module about the buffer
change and then it fills the buffer with byte value `0xaa` using
`memset()`.  Do not bother filling the buffer.  None of the other Comedi
drivers do this.

The aim is to get rid of the `prealloc_buf` member of `struct
comedi_async` (which is from a `vmap()` covering the whole buffer in
those Comedi drivers that do not use DMA), and use the per-buffer-page
addresses from the `virt_addr` member of `struct comedi_buf_page` to
access the buffer contents instead.

(If necessary, we could add a `comedi_buf_memset()` function to fill the
buffer with a byte value, but it's not worth it in this case.)

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Link: https://lore.kernel.org/r/20250415114008.5977-2-abbotti@mev.co.uk
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/comedi/drivers/ni_pcidio.c b/drivers/comedi/drivers/ni_pcidio.c
index 2d58e83420e852fa5b5538a0367c02806af376bf..2c7bb9c1ea5bd90e00bcade2862b5b467ee4fd88 100644 (file)
--- a/drivers/comedi/drivers/ni_pcidio.c
+++ b/drivers/comedi/drivers/ni_pcidio.c
@@ -747,8 +747,6 @@ static int ni_pcidio_change(struct comedi_device *dev,
        if (ret < 0)
                return ret;
 
-       memset(s->async->prealloc_buf, 0xaa, s->async->prealloc_bufsz);
-
        return 0;
 }