| Message ID | 20240215-mbly-i2c-v1-0-19a336e91dca@bootlin.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | Add Mobileye EyeQ5 support to the Nomadik I2C controller & use hrtimers for timeouts | expand |
On Thu, Feb 15, 2024 at 5:52 PM Théo Lebrun <theo.lebrun@bootlin.com> wrote: > - Add a new compatible to support Mobileye EyeQ5 which uses the same IP > block as Nomadik. Sweet! I'm amazed ST Micro licensed this "ARM PrimeCell" to Mobileye, but it's a well tested IP and used in eg ST automotive SoC:s so it's a solid product. It feels worth it for all the time I have put into maintaining it, finally some real users again! :) Yours, Linus Walleij
Hello, On Mon Feb 19, 2024 at 3:11 PM CET, Linus Walleij wrote: > On Thu, Feb 15, 2024 at 5:52 PM Théo Lebrun <theo.lebrun@bootlin.com> wrote: > > > - Add a new compatible to support Mobileye EyeQ5 which uses the same IP > > block as Nomadik. > > Sweet! I'm amazed ST Micro licensed this "ARM PrimeCell" to Mobileye, but > it's a well tested IP and used in eg ST automotive SoC:s so it's a solid > product. > > It feels worth it for all the time I have put into maintaining it, finally some > real users again! :) Using the existing Nomadik drivers with the AMBA bus infrastructure on a non-ARM platform and having it work as-is made our day here at Bootlin. We are indeed grateful for your work maintaining this platform! Regards, -- Théo Lebrun, Bootlin Embedded Linux and Kernel engineering https://bootlin.com ------------------------------------------------------------------------
Hi, This series adds two tangent features to the Nomadik I2C controller: - Add a new compatible to support Mobileye EyeQ5 which uses the same IP block as Nomadik. It has two quirks to be handled: - The memory bus only supports 32-bit accesses. A writeb() is used which we avoid. - We must write a value into a shared register region (OLB, "Other Logic Block") depending on the I2C bus speed. - Allow xfer timeouts below one jiffy by using a workqueue and hrtimers instead of a completion. The situation to be addressed is: - Many devices on the same I2C bus. - One xfer to each device is sent at regular interval. - One device gets stuck and does not answer. - With long timeouts, following devices won't get their message. A shorter timeout ensures we can still talk to the following devices. This clashes a bit with the current i2c_adapter timeout field that stores a jiffies amount. We cannot rely on it and therefore we take a value from devicetree as a µs value. If the timeout is less than a jiffy duration, we switch from standard jiffies timeout to hrtimers. There is one patch targeting a hwmon dt-bindings file: Documentation/devicetree/bindings/hwmon/lm75.yaml. The rest is touching the I2C bus driver, its bindings and platform devicetrees. About dependencies: - The series is based upon v6.8-rc4. - For testing on EyeQ5 hardware and devicetree patches, we need the base platform series from Grégory [0]. - The last commit (adding DT phandles for resets), we need the syscon series [1] that provides the reset controller node. I think there are discussions to be had about: - The handling of timeouts. Having a non-jiffy value is not driver specific. Should this change be done at the subsystem layer? The subsystem could even fetch the value from devicetree and auto-fill timeout, with a default given by the driver. Not many drivers seem to use the i2c_adapter timeout field from my quick grepping. - The DT prop for timeout. I've picked "timeout-usecs". Some drivers use vendor prefixes, but this is not vendor-specific and only a software implementation detail. - The shape of this series. Initially it was split in two. However I brought them together as they cannot be applied independently. Please tell me if a better approach is to be preferred. Those are thoughts, I'm sure people will have feedback on this. Have a nice day, Théo Lebrun [0]: https://lore.kernel.org/lkml/20240205153503.574468-1-gregory.clement@bootlin.com/ [1]: https://lore.kernel.org/lkml/20240212-mbly-clk-v6-0-c46fa1f93839@bootlin.com/ Signed-off-by: Théo Lebrun <theo.lebrun@bootlin.com> --- Théo Lebrun (13): dt-bindings: i2c: nomadik: add timeout-usecs property bindings dt-bindings: i2c: nomadik: add mobileye,eyeq5-i2c bindings and example dt-bindings: hwmon: lm75: add label property i2c: nomadik: rename private struct pointers from dev to priv i2c: nomadik: simplify IRQ masking logic i2c: nomadik: use bitops helpers i2c: nomadik: support short xfer timeouts using waitqueue & hrtimer i2c: nomadik: replace jiffies by ktime for FIFO flushing timeout i2c: nomadik: fetch timeout-usecs property from devicetree i2c: nomadik: support Mobileye EyeQ5 I2C controller MIPS: mobileye: eyeq5: add 5 I2C controller nodes MIPS: mobileye: eyeq5: add evaluation board I2C temp sensor MIPS: mobileye: eyeq5: add resets to I2C controllers Documentation/devicetree/bindings/hwmon/lm75.yaml | 4 + .../devicetree/bindings/i2c/st,nomadik-i2c.yaml | 49 +- arch/mips/boot/dts/mobileye/eyeq5-epm5.dts | 8 + arch/mips/boot/dts/mobileye/eyeq5.dtsi | 75 +++ drivers/i2c/busses/i2c-nomadik.c | 710 ++++++++++++--------- 5 files changed, 534 insertions(+), 312 deletions(-) --- base-commit: d55aa725e32849f709b61eab3b7a50b810a71a84 change-id: 20231023-mbly-i2c-7c2fbbb1299f Best regards,