Hi Mauro,
Thanks for the patchset.
On Mon, May 25, 2020 at 08:56:05AM +0200, Mauro Carvalho Chehab wrote:
> Let's reflect the current status at the TODO list, as other
> developers can help addressing issues over there.
>
> Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@xxxxxxxxxx>
> ---
> drivers/staging/media/atomisp/TODO | 188 ++++++++++++++++++++++-------
> 1 file changed, 142 insertions(+), 46 deletions(-)
>
> diff --git a/drivers/staging/media/atomisp/TODO b/drivers/staging/media/atomisp/TODO
> index 52683a704223..f297840eea90 100644
> --- a/drivers/staging/media/atomisp/TODO
> +++ b/drivers/staging/media/atomisp/TODO
> @@ -1,71 +1,165 @@
> -1. A single AtomISP driver needs to be implemented to support both
> +NOTE:
> +=====
> +
> +While the driver probes the hardware and reports itself as a
> +V4L2 driver, there are still some issues preventing it to
> +stream (at least it doesn't with the standard V4L2 applications.
> +Didn't test yet with some custom-made app for this driver).
> +Solving the related bugs and issues preventing it to work is
> +needed (items 6 and 7 from the list below).
> +
> +TODO
> +====
> +
> +1. The atomisp doesn't rely at the usual i2c stuff to discover the
> + sensors. Instead, it calls a function from atomisp_gmin_platform.c.
> + There are some hacks added there for it to wait for sensors to be
> + probed (with a timeout of 2 seconds or so).
> + This should be converted to the usual way, using V4L2 async subdev
> + framework to wait for cameras to be probed;
> +
> +2. Support for newer board-specific data (like Asus T101HA support) uses a
> + DMI match table to retrieve sensor's data, using hard-coded values.
> + It sounds feasible to retrieve those data directly from ACPI via _DSM
> + tables (like this one, associated with CAM1 at the above mentioned
> + hardware):
> +
> + Name (C1CD, Buffer (0x0220){})
> + Method (_DSM, 4, NotSerialized) // _DSM: Device-Specific Method
> + {
> + If ((Arg0 == ToUUID ("dc2f6c4f-045b-4f1d-97b9-882a6860a4be")))
> + {
> + Local0 = Package (0x12)
> + {
> + "CamId",
> + "ov2680",
> + "CamType",
> + "1",
> + "CsiPort",
> + "0",
> + "CsiLanes",
> + "1",
> + "CsiFmt",
> + "15",
> + "CsiBayer",
> + "0",
> + "CamClk",
> + "1",
> + "Regulator1p8v",
> + "0",
> + "Regulator2p8v",
> + "0"
> + }
> + Return (Local0)
> + }
> +
> + The code there at atomisp_gmin_platform has an EFI parser, but it
> + assumes that the information would be stored on a different way.
> +
> + As the Kernel has support for reading data from _DSM, via
> + acpi_evaluate_dsm(), it sounds doable to use such infra and remove the
> + DMI match, at least for some devices. This will likely allow covering
> + more devices that could also be using the same EFI UUID.
> +
> +3. Switch the driver to use pm_runtime stuff. Right now, it probes the
> + existing PMIC code and sensors call it directly.
> +
> +4. There's a problem at the sensor drivers: when trying to set a video
> + format, the atomisp main driver calls the sensor drivers with the
> + sensor turned off. This causes them to fail.
> +
> + The only exception is the atomisp-ov2880, which has a hack inside it
> + to turn it on when VIDIOC_S_FMT is called.
> +
> + The right fix seems to power on the sensor when a video device is
> + opened (or at the first VIDIOC_ ioctl - except for VIDIOC_QUERYCAP),
> + powering it down at close() syscall.
> +
> + Such kind of control would need to be done inside the atomisp driver,
> + not at the sensors code.
> +
> +5. There are several issues related to memory management, causing
> + crashes. The atomisp splits the memory management on three separate
> + regions:
> +
> + - dynamic pool;
> + - reserved pool;
> + - generic pool
> +
> + The code implementing it is at:
> +
> + drivers/staging/media/atomisp/pci/hmm/
> +
> + It also has a separate code for managing DMA buffers at:
> +
> + drivers/staging/media/atomisp/pci/mmu/
> +
> + The code there is really dirty, ugly and probably wrong. I fixed
> + one bug there already, but the best would be to just trash it and use
> + something else. Maybe the code from the newer intel driver could
> + serve as a model:
> +
> + drivers/staging/media/ipu3/ipu3-mmu.c
> +
> + But converting it to use something like that is painful and may
> + cause some breakages.
> +
> +6. There is some issues at the frame receive logic, causing the
> + DQBUF ioctls to fail.
> +
> +7. A single AtomISP driver needs to be implemented to support both
> Baytrail (BYT and Cherrytail (CHT) platforms at the same time.
s/BYT\K/)/
> The current driver is a mechanical and hand combined merge of the
> two using several runtime macros, plus some ifdef ISP2401 to select the
> CHT version. Yet, there are some ISP-specific headers that change the
> driver's behavior during compile time.
>
> -2. The file structure needs to get tidied up to resemble a normal Linux
> +8. The file structure needs to get tidied up to resemble a normal Linux
> driver.
>
> -3. Lots of the midlayer glue. unused code and abstraction needs removing.
> +9. Lots of the midlayer glue. unused code and abstraction needs removing.
>
> -3. The sensor drivers read MIPI settings from EFI variables or default to the
> - settings hard-coded in the platform data file for different platforms.
> - It should be possible to improve it, by adding support for _DSM tables.
> +10. The AtomISP driver includes some special IOCTLS (ATOMISP_IOC_XXXX_XXXX)
> + and controls that require some cleanup. Some of those code may have
> + been removed during the cleanups. They could be needed in order to
> + properly support 3A algorithms
I'd add: "The IOCTL interface needs to more documentation." Actually I
believe the better way to implement that would be to use a similar
parameter buffer IPU3 IMGU driver uses.
>
> -4. The sensor drivers use PMIC and the regulator framework API. In the ideal
> - world it would be using ACPI but that's not how the existing devices work.
> +11. The ISP code has some dependencies of the exact FW version.
> + The version defined in pci/sh_css_firmware.c:
>
> -5. The AtomISP driver includes some special IOCTLS (ATOMISP_IOC_XXXX_XXXX)
> - and controls that require some cleanup.
> + BYT (isp2400): "irci_stable_candrpv_0415_20150521_0458"
>
> -6. Correct Coding Style. Please don't send coding style patches for this
> - driver until the other work is done.
> + CHT (isp2401): "irci_ecr - master_20150911_0724"
>
> -7. The ISP code has some dependencies of the exact FW version.
> - The version defined in pci/sh_css_firmware.c:
> - BYT:
> - static const char *isp2400_release_version = STR(irci_stable_candrpv_0415_20150521_0458);
> + Those versions don't seem to be available anymore. On the tests we've
> + done so far, this version also seems to work for CHT:
>
> - CHT:
> - static const char *isp2401_release_version = STR(irci_ecr - master_20150911_0724);
> + "irci_stable_candrpv_0415_20150521_0458"
>
> - Those versions don't seem to be available anymore. On the tests we've
> - done so far, this version also seems to work for isp2401:
> + Which can be obtainable from Yocto Atom ISP respository.
>
> - irci_stable_candrpv_0415_20150521_0458
> + but this was not thoroughly tested.
>
> - At some point we may need to round up a few driver versions and see if
> - there are any specific things that can be done to fold in support for
> - multiple firmware versions.
> + At some point we may need to round up a few driver versions and see if
> + there are any specific things that can be done to fold in support for
> + multiple firmware versions.
Well, agreed in principle, but this could be difficult.
>
> -8. Switch to V4L2 async API to set up sensor, lens and flash devices.
> - Control those devices using V4L2 sub-device API without custom
> - extensions.
> +12. Switch to standard V4L2 sub-device API for sensor and lens. In
> + particular, the user space API needs to support V4L2 controls as
> + defined in the V4L2 spec and references to atomisp must be removed from
> + these drivers.
>
> -9. Switch to standard V4L2 sub-device API for sensor and lens. In
> - particular, the user space API needs to support V4L2 controls as
> - defined in the V4L2 spec and references to atomisp must be removed from
> - these drivers.
> -
> -10. Use LED flash API for flash LED drivers such as LM3554 (which already
> +13. Use LED flash API for flash LED drivers such as LM3554 (which already
> has a LED class driver).
>
> -11. Switch from videobuf1 to videobuf2. Videobuf1 is being removed!
> +14. Switch from videobuf1 to videobuf2. Videobuf1 is being removed!
>
> -12. There are some memory management code that seems to be
> - forked from Kernel 3.10 inside hmm/ directory. Get rid of it,
> - making the driver to use a more standard memory management module.
> +15. Correct Coding Style. Please refrain sending coding style patches
> + for this driver until the other work is done, as there will be a lot
> + of code churn until this driver becomes functional again.
>
> -13. While the driver probes the hardware and reports itself as a
> - V4L2 driver, there are still some issues preventing it to
> - stream (at least it doesn't with the standard V4L2 applications.
> - Didn't test yet with some custom-made app for this driver).
> - Solving the related bugs and issues preventing it to work is
> - needed.
> -
> -Limitations:
> +Limitations
> +===========
>
> 1. To test the patches, you also need the ISP firmware
>
> @@ -84,6 +178,8 @@ Limitations:
> It will not detect those devices enumerated via ACPI as a field of the
> i915 GPU driver.
>
> + There are some patches adding i915 GPU support floating at the Yocto's
> + Aero repository (so far, untested upstream).
> +
> 4. The driver supports only v2 of the IPU/Camera. It will not work with the
> versions of the hardware in other SoCs.
> -
> --
> 2.26.2
>
--
Sakari Ailus
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