Hi Mark,
On 2024-05-12 22:41, Mark Kettenis wrote:
Date: Sat, 11 May 2024 22:55:18 +0200 From: Jonas Karlman jonas@kwiboo.se
Hi Mark,
On 2024-05-11 21:57, Mark Kettenis wrote:
Date: Sat, 11 May 2024 20:47:40 +0200 From: Jonas Karlman jonas@kwiboo.se
Hi Jonas & Alex,
Hi Alex,
On 2024-05-11 19:44, Alex Bee wrote:
Hi Jonas,
Am 11.05.24 um 13:28 schrieb Jonas Karlman:
This series add gpio request() and pinctrl gpio_request_enable() ops so that a gpio requested pin automatically use gpio pinmux and U-Boot behaves more similar to Linux kernel.
I'm not sure that's a good idea. While linux does it the same way, we really shouldn't expect every software/os/ … which uses DT (now or in future) to implicitly switch the pin function when using a pin as gpio. So the real fix would probably be to add the the correct pinctrl settings to the upstream DT of those boards and sync it later on (not sure those if those SoCs already using OF_UPSTREAM) and leave the -u-boot.dtsi-"hack" alone for now.
I missed Alex's mail, but OpenBSD certainly is one of the OSes that could break if the pinctrl settings get removed. We currently have no code to automatically mux the gpio pins on these Rockchip SoCs. I suppose as long as U-Boot probes the PCIe bus, the pins will already be muxed correctly and things will continue to work. But I think there are certain boot scenarios where this won't happen.
The control FDT on the known affected boards was only patched to prevent the boards from a full device freeze when PCIe was enumerated. An OS should probably not depend on a workaround made for U-Boot use.
Sure, but I think that means we should try to minimise the number of workarounds in U-Boot ;).
Agree, and something this series tries to accomplish, removing one "bad" workaround so that once upstream DT is fixed and it trickle down to dts/upstream/ nothing else needs to be changed in U-Boot.
Is it common for *BDS to use the control FDT or is it more common that a separate .dtb-file to be loaded during boot?
Not sure what the other BSDs do; at this point they're largely separate codebases that just share a common ancestry. And I don't really like the term "control FDT"; in ideal world there should be just be a single FDT that gets used by the various firmware layers, U-Boot and the OS. But yes, my goal is to make OpenBSD work with FDT provided by U-Boot without loading a separte .dtb file.
Thanks for the insights. Typically I test linux-next kernel using the FDT provided by U-Boot. Any suggestions on how I can get a minimal OpenBSD snapshot to boot on e.g. a RK356x board?
To recap, the issue on e.g. ROCK 3A is that the upstream DT use pinctrl to signal PCIE30X2 CLKREQn_M1/WAKEn_M1/PERSTn_M1 function, DT also specify a reset-gpios prop pointing on PERSTn_M1. To me this seem like a correct description of HW.
Actually I'm starting to think that it isn't. If you look at table 11-11 in Part 2 of the RK3588 TRM (V1.0) you'll see that the pcie_perst_n signal is designated as input. The corrsponding chapter is missing from the copy of the RK3568 TRM I have, but it is likely that the same applies to the PCIe conroller on the RK3568 SoC. Now these PCIe controllers can function in either Root Complex (RC) or Endpoint (EP) mode. And given the the pcie_perst_n signal is designated as input I think that means that the PERSTn_M1 function only makes sense when the controller is in EP mode. So for the majority of the boards that use the PCIe controller in RC mode, the DT should only configure the CLKREQn_M1 and WAKEn_M1 functions and configure the pin that is used to output PERST# as a GPIO.
Thanks for this insights!
I can also clarify that the freeze only happens when a PCIe device is not attached, removing the reset-gpio prop and leaving the pin in PERSTn_M1 function my nvme drive is discovered correctly. Without anything attached the device freeze during "pci enum".
When U-Boot probe the PCIE30X2 device the pinctrl driver would automatically configure CLKREQn_M1/WAKEn_M1/PERSTn_M1 function.
When U-Boot RK PCIe driver try to use the reset-gpios pin the device would freeze unless the PERSTn pin is first re-configured for gpio use.
Current workaround in U-Boot throws away the existing upstream pinctrl and replace it to only configure gpio func on the PERSTn pin. This also leaves the CLKREQn and WAKEn to incorrectly use gpio func.
With this series I try to cleanup the old workaround that I added without much insight beyond: device no longer freeze and nvme "works" :-)
I've wondered in the past what the purpose of the gpio-ranges properties was. I never considered that they could be used to automatically mux the pins for GPIO since the gpio-ranges mapping provides no indication of what the correct pin settings arefor the GPIO pins.
The gpio-ranges prop is only used to provide details on how the pins are mapped between gpio and pin controller. It is not used to change any muxing. But the property is required to make the U-Boot helpers pinctrl_gpio_request()/pinctrl_gpio_free() work and figure out what pinctrl udevice to use if another driver use e.g. gpio_request_by_name() to request use of a pin for gpio use.
But that means you rely on the Linux (and now U-Boot) driver interfaces. What I was saying is that this is all rather implicit and not explicitly documented in the device tree bindings.
I fully understand this, however, from a developer perspective and seeing how there is no API to configure pinmux from code but there is an API to request and work with gpio, I would expect that the abstraction layer handle anything needed to be able to use the returned gpio.
Keep in mind that this series should not change any behavior except for the special case when DT pinctrl may configure a pin for non-gpio function and later U-Boot request the pin to be used for gpio.
To me such a case would be suspicious. What would be the purpose of such a configuration? And wouldn't this mean that you now implictly rely on the gpio being requested after the pinctl config has been applied?
Main purpose is to ensure the U-Boot gpio API works as expected for debugging and development purposes. For final DTs I am expecting that pinctrl is configured correctly.
Regards, Jonas
I fully agree that the pinctrl for the problematic boards should be corrected in upstream DT, but that is a separate issue and should not block adding support for the request()/gpio_request_enable() ops.
While the pcie reset-gpios full board freeze that was my driving factor to fully implement the gpio request() ops it is not the only use case, using the gpio cmd on a pin that use a non-gpio pinmux is another.
Or do you see any technical issue with having the gpio request() ops implemented and having it ensure gpio pinmux is used on a gpio requested pin? Similar to how gpio/pinctrl is behaving in Linux and on some other platforms in U-Boot?
Well, it removes the incentive to fix the upstream DTs and would make it harder to notice missing pinctrls in the DTs.
I can understand that, but gpio pinmux is default so any missing pinctrl would still cause issues, this changes nothing in that regard.
This only affect if pinctrl exists and pin gets configured for non-gpio function use. And later a driver/cmd tries to use such pin for gpio use. Before this patch the use of gpio_request() would not change the pin mux for gpio use. After this series when code explicily request a pin for gpio use the pinctrl driver gets notified that it should change pinmux of the pin for gpio use.
Regards, Jonas
Cheers,
Mark
Alex
With the gpio and pinctrl ops implemented this series also remove a PCIe reset-gpios related device lock-up workaround from board u-boot.dtsi.
PX30, RK3066, RK3188, RK356x and RK3588 are the only SoCs that currently define gpio-ranges props and is affected by this series.
A follow up series adding support for the pinmux status cmd will also add gpio-ranges props for remaining RK SoCs.
Jonas Karlman (4): pinctrl: rockchip: Add gpio_request_enable() ops gpio: rockchip: Add request() ops rockchip: rk3568-rock-3a: Drop PCIe reset-gpios workaround rockchip: rk3568-radxa-e25: Drop PCIe reset-gpios workaround
arch/arm/dts/rk3568-radxa-e25-u-boot.dtsi | 12 ------- arch/arm/dts/rk3568-rock-3a-u-boot.dtsi | 12 ------- drivers/gpio/rk_gpio.c | 10 ++++++ .../pinctrl/rockchip/pinctrl-rockchip-core.c | 31 +++++++++++++++++++ 4 files changed, 41 insertions(+), 24 deletions(-)