linux/drivers/media/usb
Robert Schlabbach e704b44b55 media: dvb-core: Enhance shared multi-frontend support
Drivers for devices with multiple frontends which cannot be used
concurrently due to hardware limitations which enforce that restriction
by setting the mfe_shared field to 1 exhibit rather unfriendly behavior
towards applications: The unavailable frontend devices cannot be opened
at all, not even for read-only access to query information. Even worse,
any open call is blocked for 5 seconds by default.

Allow drivers for such devices to behave like regular busy frontend
devices instead, i.e. still allowing concurrent read access to the
unavailable frontend and denying concurrent write access with -EBUSY
without delay.

This patch does not alter the behavior of any existing driver to avoid
regressions. Driver developers who wish to take advantage of this must
ensure their driver can handle all read-only accesses to the unavailable
frontend, and indicate the capability by setting the mfe_shared field to
2 instead of 1.

Add a check to dvb-usb-init.c when automatically setting the mfe_shared
field that when a driver has already set the field to 2, it is not
overwritten.

Document the additional capability in the code comment about mfe_shared.

Link: https://lore.kernel.org/linux-media/trinity-22c77578-26b0-4867-9ff7-2668e5d22c64-1642799929896@3c-app-gmx-bap04
Signed-off-by: Robert Schlabbach <robert_s@gmx.net>
Tested-by: Robert Schlabbach <robert_s@gmx.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
2022-11-25 09:59:09 +00:00
..
airspy media: airspy: fix memory leak in airspy probe 2022-08-30 07:31:42 +02:00
as102
au0828 media: vb2/au0828: move the v4l_vb2q_enable_media_source to the au0828 driver 2022-11-25 07:41:40 +00:00
b2c2 media: flexcop-usb: use usb_endpoint_maxp() 2022-09-26 10:59:25 +02:00
cx231xx media: avoid use of 'videobuf' 2022-08-29 16:27:18 +02:00
dvb-usb media: dvb-core: Enhance shared multi-frontend support 2022-11-25 09:59:09 +00:00
dvb-usb-v2 media: usb/dvb-usb-v2: fix repeated words in comments 2022-09-24 08:47:01 +02:00
em28xx media: dvb-frontends: a8293: fix LNB powerup failure in PCTV 461e 2022-11-25 09:55:55 +00:00
go7007 media: usb: go7007: s2250-board: Convert to i2c's .probe_new() 2022-11-21 11:04:46 +01:00
gspca media: gspca: Fix typo 'the the' in comment 2022-08-29 15:32:14 +02:00
hackrf media: Kconfig: cleanup VIDEO_DEV dependencies 2022-03-18 05:58:35 +01:00
hdpvr media: hdpvr: fix error value returns in hdpvr_read 2022-06-27 09:02:50 +01:00
msi2500 media: usb/msi2500: fix repeated words in comments 2022-09-24 08:46:38 +02:00
pvrusb2 media: avoid use of 'videobuf' 2022-08-29 16:27:18 +02:00
pwc media: Kconfig: cleanup VIDEO_DEV dependencies 2022-03-18 05:58:35 +01:00
s2255 media: Kconfig: cleanup VIDEO_DEV dependencies 2022-03-18 05:58:35 +01:00
siano media: siano: remove duplicate USB device IDs 2021-12-07 11:29:58 +01:00
stk1160 media: stk1160: use dma_alloc_noncontiguous API 2022-03-07 11:01:22 +01:00
ttusb-budget media: dvb-ttusb-budget: cleanup printk logic 2020-09-03 11:15:47 +02:00
ttusb-dec media: ttusb-dec: avoid release of non-acquired mutex 2021-09-30 10:07:40 +02:00
usbtv media: usbtv: Add PAL-Nc standard 2022-06-20 10:30:30 +01:00
uvc USB/Thunderbolt changes for 6.1-rc1 2022-10-07 16:48:26 -07:00
Kconfig media: tm6000: deprecate this driver 2022-08-29 16:43:00 +02:00
Makefile media: tm6000: deprecate this driver 2022-08-29 16:43:00 +02:00