| Message ID | 20220803075850.1196988-1-hljunggr@cisco.com |
|---|---|
| Headers | show |
| Series | Add the cat24c208 EDID EEPROM driver + new EDID capability | expand |
Hi Erling, (CC'ing the linux-i2c mailing list and Srinivas, the maintainer of the nvmem framework) Thank you for the patches. On Wed, Aug 03, 2022 at 09:58:45AM +0200, Erling Ljunggren wrote: > This series adds support for the standalone cat24c208 EDID EEPROM i2c device. > Usually EDID support is part of an HDMI receiver, but this is a standalone EEPROM. > > Note that EEPROMs for EDIDs are not regular EEPROM devices, these are dual port > devices that follow the VESA E-DDC standard. > > Since this is a standalone device that does not capture any video a new > V4L2_CAP_EDID_MEMORY capability is introduced to represent such devices. > Note that such a device doesn't have to be an EEPROM, it can also be > implemented using a microcontroller, for example. Hence the use of the generic > word 'MEMORY'. Why can't this be exposed as a nvmem device, like other types of eeproms here ? > The new capability uses the free bit 0x00000008. But we are running out of > capability bits: only 0x40000000 and 0x00000008 are free at the moment. > > There is one other capability V4L2_CAP_ASYNCIO (0x02000000) that is not used > at all, it was never implemented. Wouldn't it be better to define > V4L2_CAP_ASYNCIO to 0, mark it as obsolete, and instead reuse it for this > V4L2_CAP_EDID_MEMORY capability? > > v2: > - fix dt binding example > - rename i2c client variables in data struct > - fix include: of_device.h -> mod_devicetable.h > - Sorted makefile > - used define EDID_OFFSET_EXT_FLAG instead of magic number > - removed of_match_ptr > - added bus_info > - remove unneeded headers > - add depends on OF to Kconfig > > Erling Ljunggren (4): > media: videodev2.h: add V4L2_CAP_EDID_MEMORY > media: docs: Add V4L2_CAP_EDID_MEMORY > dt-bindings: media: add cat24c208 bindings > media: v4l2-dev: handle V4L2_CAP_EDID_MEMORY > > Jonathan Selnes (1): > media: i2c: cat24c208: driver for the cat24c208 EDID EEPROM > > .../bindings/media/i2c/onnn,cat24c208.yaml | 40 ++ > .../userspace-api/media/v4l/biblio.rst | 11 + > .../media/v4l/vidioc-querycap.rst | 7 + > .../media/videodev2.h.rst.exceptions | 1 + > MAINTAINERS | 7 + > drivers/media/i2c/Kconfig | 9 + > drivers/media/i2c/Makefile | 1 + > drivers/media/i2c/cat24c208.c | 421 ++++++++++++++++++ > drivers/media/v4l2-core/v4l2-dev.c | 8 + > include/uapi/linux/videodev2.h | 1 + > 10 files changed, 506 insertions(+) > create mode 100644 Documentation/devicetree/bindings/media/i2c/onnn,cat24c208.yaml > create mode 100644 drivers/media/i2c/cat24c208.c
On 03/08/2022 11:14, Laurent Pinchart wrote: > Hi Erling, > > (CC'ing the linux-i2c mailing list and Srinivas, the maintainer of the > nvmem framework) > > Thank you for the patches. > > On Wed, Aug 03, 2022 at 09:58:45AM +0200, Erling Ljunggren wrote: >> This series adds support for the standalone cat24c208 EDID EEPROM i2c device. >> Usually EDID support is part of an HDMI receiver, but this is a standalone EEPROM. >> >> Note that EEPROMs for EDIDs are not regular EEPROM devices, these are dual port >> devices that follow the VESA E-DDC standard. >> >> Since this is a standalone device that does not capture any video a new >> V4L2_CAP_EDID_MEMORY capability is introduced to represent such devices. >> Note that such a device doesn't have to be an EEPROM, it can also be >> implemented using a microcontroller, for example. Hence the use of the generic >> word 'MEMORY'. > > Why can't this be exposed as a nvmem device, like other types of eeproms > here ? Because it isn't. Same discussion I had with Andy: it's not a regular eeprom but a dedicated eeprom for EDIDs. And we have support for that already in V4L2. It's specific to receivers as well, so the only subsystem it belongs to is V4L2. See the discussion I had with Andy on this: https://patchwork.linuxtv.org/project/linux-media/patch/20220728114050.2400475-5-hljunggr@cisco.com/ Regards, Hans > >> The new capability uses the free bit 0x00000008. But we are running out of >> capability bits: only 0x40000000 and 0x00000008 are free at the moment. >> >> There is one other capability V4L2_CAP_ASYNCIO (0x02000000) that is not used >> at all, it was never implemented. Wouldn't it be better to define >> V4L2_CAP_ASYNCIO to 0, mark it as obsolete, and instead reuse it for this >> V4L2_CAP_EDID_MEMORY capability? >> >> v2: >> - fix dt binding example >> - rename i2c client variables in data struct >> - fix include: of_device.h -> mod_devicetable.h >> - Sorted makefile >> - used define EDID_OFFSET_EXT_FLAG instead of magic number >> - removed of_match_ptr >> - added bus_info >> - remove unneeded headers >> - add depends on OF to Kconfig >> >> Erling Ljunggren (4): >> media: videodev2.h: add V4L2_CAP_EDID_MEMORY >> media: docs: Add V4L2_CAP_EDID_MEMORY >> dt-bindings: media: add cat24c208 bindings >> media: v4l2-dev: handle V4L2_CAP_EDID_MEMORY >> >> Jonathan Selnes (1): >> media: i2c: cat24c208: driver for the cat24c208 EDID EEPROM >> >> .../bindings/media/i2c/onnn,cat24c208.yaml | 40 ++ >> .../userspace-api/media/v4l/biblio.rst | 11 + >> .../media/v4l/vidioc-querycap.rst | 7 + >> .../media/videodev2.h.rst.exceptions | 1 + >> MAINTAINERS | 7 + >> drivers/media/i2c/Kconfig | 9 + >> drivers/media/i2c/Makefile | 1 + >> drivers/media/i2c/cat24c208.c | 421 ++++++++++++++++++ >> drivers/media/v4l2-core/v4l2-dev.c | 8 + >> include/uapi/linux/videodev2.h | 1 + >> 10 files changed, 506 insertions(+) >> create mode 100644 Documentation/devicetree/bindings/media/i2c/onnn,cat24c208.yaml >> create mode 100644 drivers/media/i2c/cat24c208.c >
On Wed, 03 Aug 2022 09:58:48 +0200, Erling Ljunggren wrote: > Add devicetree bindings for new cat24c208 EDID EEPROM driver. > > Signed-off-by: Erling Ljunggren <hljunggr@cisco.com> > --- > .../bindings/media/i2c/onnn,cat24c208.yaml | 40 +++++++++++++++++++ > 1 file changed, 40 insertions(+) > create mode 100644 Documentation/devicetree/bindings/media/i2c/onnn,cat24c208.yaml > Reviewed-by: Rob Herring <robh@kernel.org>