Re: [PATCH] media: stkwebcam: move stk_camera_read_reg() scratch buffer to struct stk_camera

From: Tom Rix
Date: Wed Apr 27 2022 - 15:09:59 EST



On 4/26/22 10:38 PM, Hans Verkuil wrote:
Hi Tom,

On 12/03/2022 18:30, trix@xxxxxxxxxx wrote:
From: Tom Rix <trix@xxxxxxxxxx>

In stk_camera_read_reg() a single byte buffer is alloc-ed and
freed on every function call. Since the size is known,
move the buffer to the struct stk_camera where it will be alloc-ed
and freed once.
I read the replies to this patch, but I am not certain if you still want
this patch to be merged, or will make a v2. I have no problem applying this
patch as-is, but I just want to have confirmation that there won't be a v2.

Merged as-is is fine.

Thanks

Tom



Regards,

Hans

Signed-off-by: Tom Rix <trix@xxxxxxxxxx>
---
drivers/media/usb/stkwebcam/stk-webcam.c | 11 ++---------
drivers/media/usb/stkwebcam/stk-webcam.h | 2 ++
2 files changed, 4 insertions(+), 9 deletions(-)

diff --git a/drivers/media/usb/stkwebcam/stk-webcam.c b/drivers/media/usb/stkwebcam/stk-webcam.c
index 5b822214ccc5c..787edb3d47c23 100644
--- a/drivers/media/usb/stkwebcam/stk-webcam.c
+++ b/drivers/media/usb/stkwebcam/stk-webcam.c
@@ -150,25 +150,18 @@ int stk_camera_write_reg(struct stk_camera *dev, u16 index, u8 value)
int stk_camera_read_reg(struct stk_camera *dev, u16 index, u8 *value)
{
struct usb_device *udev = dev->udev;
- unsigned char *buf;
int ret;
- buf = kmalloc(sizeof(u8), GFP_KERNEL);
- if (!buf)
- return -ENOMEM;
-
ret = usb_control_msg(udev, usb_rcvctrlpipe(udev, 0),
0x00,
USB_DIR_IN | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
0x00,
index,
- buf,
+ &dev->read_reg_scratch,
sizeof(u8),
500);
if (ret >= 0)
- *value = *buf;
-
- kfree(buf);
+ *value = dev->read_reg_scratch;
if (ret < 0)
return ret;
diff --git a/drivers/media/usb/stkwebcam/stk-webcam.h b/drivers/media/usb/stkwebcam/stk-webcam.h
index 14519e5308b18..136decffe9ced 100644
--- a/drivers/media/usb/stkwebcam/stk-webcam.h
+++ b/drivers/media/usb/stkwebcam/stk-webcam.h
@@ -105,6 +105,8 @@ struct stk_camera {
struct list_head sio_avail;
struct list_head sio_full;
unsigned sequence;
+
+ u8 read_reg_scratch;
};
#define vdev_to_camera(d) container_of(d, struct stk_camera, vdev)