[PATCH 6.1.y] media: rc: ttusbir: respect DMA coherency rules

Sasha Levin
2026-05-01T17:13:24Z

From: Oliver Neukum <oneukum@suse.com>

[ Upstream commit 50acaad3d202c064779db8dc3d010007347f59c7 ]

Buffers must not share a cache line with other data structures.
Allocate separately.

Fixes: 0938069fa0897 ("[media] rc: Add support for the TechnoTrend USB IR Receiver")
Cc: stable@vger.kernel.org
Signed-off-by: Oliver Neukum <oneukum@suse.com>
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>
[ kept kzalloc(sizeof(*tt), GFP_KERNEL) instead of kzalloc_obj() ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/media/rc/ttusbir.c | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/drivers/media/rc/ttusbir.c b/drivers/media/rc/ttusbir.c
index 560a26f3965cf..dde446a95eaa9 100644
--- a/drivers/media/rc/ttusbir.c
+++ b/drivers/media/rc/ttusbir.c
@@ -32,7 +32,7 @@ struct ttusbir {

struct led_classdev led;
struct urb *bulk_urb;
- uint8_t bulk_buffer[5];
+ u8 *bulk_buffer;
int bulk_out_endp, iso_in_endp;
bool led_on, is_led_on;
atomic_t led_complete;
@@ -186,13 +186,16 @@ static int ttusbir_probe(struct usb_interface *intf,
struct rc_dev *rc;
int i, j, ret;
int altsetting = -1;
+ u8 *buffer;

tt = kzalloc(sizeof(*tt), GFP_KERNEL);
+ buffer = kzalloc(5, GFP_KERNEL);
rc = rc_allocate_device(RC_DRIVER_IR_RAW);
- if (!tt || !rc) {
+ if (!tt || !rc || buffer) {
ret = -ENOMEM;
goto out;
}
+ tt->bulk_buffer = buffer;

/* find the correct alt setting */
for (i = 0; i < intf->num_altsetting && altsetting == -1; i++) {
@@ -281,8 +284,8 @@ static int ttusbir_probe(struct usb_interface *intf,
tt->bulk_buffer[3] = 0x01;

usb_fill_bulk_urb(tt->bulk_urb, tt->udev, usb_sndbulkpipe(tt->udev,
- tt->bulk_out_endp), tt->bulk_buffer, sizeof(tt->bulk_buffer),
- ttusbir_bulk_complete, tt);
+ tt->bulk_out_endp), tt->bulk_buffer, 5,
+ ttusbir_bulk_complete, tt);

tt->led.name = "ttusbir:green:power";
tt->led.default_trigger = "rc-feedback";
@@ -351,6 +354,7 @@ static int ttusbir_probe(struct usb_interface *intf,
kfree(tt);
}
rc_free_device(rc);
+ kfree(buffer);

return ret;
}
@@ -373,6 +377,7 @@ static void ttusbir_disconnect(struct usb_interface *intf)
}
usb_kill_urb(tt->bulk_urb);
usb_free_urb(tt->bulk_urb);
+ kfree(tt->bulk_buffer);
usb_set_intfdata(intf, NULL);
kfree(tt);
}
--
2.53.0