From: YongSu Yoo <yongsuyoo0215@xxxxxxxxx> The function of "dvb_ca_en50221_write_data" at source/drivers/media /dvb-core/dvb_ca_en50221.c is used for two cases. The first case is for writing APDU data in the function of "dvb_ca_en50221_io_write" at source/drivers/media/dvb-core/ dvb_ca_en50221.c. The second case is for writing the host link buf size on the Command Register in the function of "dvb_ca_en50221_link_init" at source/drivers/media/dvb-core/dvb_ca_en50221.c. In the second case, there exists a bug like followings. In the function of the "dvb_ca_en50221_link_init", after a TV host calculates the host link buf_size, the TV host writes the calculated host link buf_size on the Size Register. Accroding to the en50221 Spec (the page 60 of https://dvb.org/wp-content/uploads/2020/02/En50221.V1.pdf), before this writing operation, the "SW(CMDREG_SW)" flag in the Command Register should be set. We can see this setting operation in the function of the "dvb_ca_en50221_link_init" like below. ... if ((ret = ca->pub->write_cam_control(ca->pub, slot, CTRLIF_COMMAND, IRQEN | CMDREG_SW)) != 0) return ret; ... But, after that, the real writing operation is implemented using the function of the "dvb_ca_en50221_write_data" in the function of "dvb_ca_en50221_link_init", and the "dvb_ca_en50221_write_data" includes the function of "ca->pub->write_cam_control", and the function of the "ca->pub->write_cam_control" in the function of the "dvb_ca_en50221_wrte_data" does not include "CMDREG_SW" flag like below. ... if ((status = ca->pub->write_cam_control(ca->pub, slot, CTRLIF_COMMAND, IRQEN | CMDREG_HC)) != 0) ... In the above source code, we can see only the "IRQEN | CMDREG_HC", but we cannot see the "CMDREG_SW". The "CMDREG_SW" flag which was set in the function of the "dvb_ca_en50221_link_init" was rollbacked by the follwoing function of the "dvb_ca_en50221_write_data". This is a bug. and this bug causes that the calculated host link buf_size is not properly written in the CI module. Through this patch, we fix this bug. Link: https://lore.kernel.org/linux-media/20220818125027.1131-1-yongsuyoo0215@xxxxxxxxx Signed-off-by: YongSu Yoo <yongsuyoo0215@xxxxxxxxx> Signed-off-by: Mauro Carvalho Chehab <mchehab@xxxxxxxxxx> --- drivers/media/dvb-core/dvb_ca_en50221.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/drivers/media/dvb-core/dvb_ca_en50221.c b/drivers/media/dvb-core/dvb_ca_en50221.c index c2d2792227f8..b6ca29dfb184 100644 --- a/drivers/media/dvb-core/dvb_ca_en50221.c +++ b/drivers/media/dvb-core/dvb_ca_en50221.c @@ -187,7 +187,7 @@ static void dvb_ca_en50221_thread_wakeup(struct dvb_ca_private *ca); static int dvb_ca_en50221_read_data(struct dvb_ca_private *ca, int slot, u8 *ebuf, int ecount); static int dvb_ca_en50221_write_data(struct dvb_ca_private *ca, int slot, - u8 *ebuf, int ecount); + u8 *ebuf, int ecount, int size_write_flag); /** * findstr - Safely find needle in haystack. @@ -370,7 +370,7 @@ static int dvb_ca_en50221_link_init(struct dvb_ca_private *ca, int slot) ret = dvb_ca_en50221_wait_if_status(ca, slot, STATUSREG_FR, HZ / 10); if (ret) return ret; - ret = dvb_ca_en50221_write_data(ca, slot, buf, 2); + ret = dvb_ca_en50221_write_data(ca, slot, buf, 2, CMDREG_SW); if (ret != 2) return -EIO; ret = ca->pub->write_cam_control(ca->pub, slot, CTRLIF_COMMAND, IRQEN); @@ -778,11 +778,13 @@ static int dvb_ca_en50221_read_data(struct dvb_ca_private *ca, int slot, * @buf: The data in this buffer is treated as a complete link-level packet to * be written. * @bytes_write: Size of ebuf. + * @size_write_flag: A flag on Command Register which says whether the link size + * information will be writen or not. * * return: Number of bytes written, or < 0 on error. */ static int dvb_ca_en50221_write_data(struct dvb_ca_private *ca, int slot, - u8 *buf, int bytes_write) + u8 *buf, int bytes_write, int size_write_flag) { struct dvb_ca_slot *sl = &ca->slot_info[slot]; int status; @@ -817,7 +819,7 @@ static int dvb_ca_en50221_write_data(struct dvb_ca_private *ca, int slot, /* OK, set HC bit */ status = ca->pub->write_cam_control(ca->pub, slot, CTRLIF_COMMAND, - IRQEN | CMDREG_HC); + IRQEN | CMDREG_HC | size_write_flag); if (status) goto exit; @@ -1508,7 +1510,7 @@ static ssize_t dvb_ca_en50221_io_write(struct file *file, mutex_lock(&sl->slot_lock); status = dvb_ca_en50221_write_data(ca, slot, fragbuf, - fraglen + 2); + fraglen + 2, 0); mutex_unlock(&sl->slot_lock); if (status == (fraglen + 2)) { written = 1; -- 2.40.1
