Re: [PATCH] arm64: dts: rockchip: Explicitly request UFS reset pin on RK3576

[Quentin Schulz <quentin.schulz@cherry.de>]

Hi Alexey,

On 1/19/26 10:22 AM, Alexey Charkov wrote:
> Rockchip RK3576 UFS controller uses a dedicated pin to reset the connected
> UFS device, which can operate either in a hardware controlled mode or as a
> GPIO pin.
> 
> Power-on default is GPIO mode, but the boot ROM reconfigures it to a
> hardware controlled mode if it uses UFS to load the next boot stage.
> 
> Given that existing bindings (and rk3576.dtsi) expect a GPIO-controlled
> device reset, request the required pin config explicitly.
> 
> This doesn't appear to affect Linux, but it does affect U-boot:
> 
> Before:
> => md.l 0x2604b398
> 2604b398: 00000011 00000000 00000000 00000000  ................
> < ... snip ... >
> => ufs init
> ufshcd-rockchip ufshc@2a2d0000: [RX, TX]: gear=[3, 3], lane[2, 2], pwr[FASTAUTO_MODE, FASTAUTO_MODE], rate = 2
> => md.l 0x2604b398
> 2604b398: 00000011 00000000 00000000 00000000  ................
> 
> After:
> => md.l 0x2604b398
> 2604b398: 00000011 00000000 00000000 00000000  ................
> < ... snip ...>
> => ufs init
> ufshcd-rockchip ufshc@2a2d0000: [RX, TX]: gear=[3, 3], lane[2, 2], pwr[FASTAUTO_MODE, FASTAUTO_MODE], rate = 2
> => md.l 0x2604b398
> 2604b398: 00000010 00000000 00000000 00000000  ................
> 
> (0x2604b398 is the respective pin mux register, with its BIT0 driving the
> mode of UFS_RST: unset = GPIO, set = hardware controlled UFS_RST)
> 
> This helps ensure that GPIO-driven device reset actually fires when the
> system requests it, not when whatever black box magic inside the UFSHC
> decides to reset the flash chip.
> 
> Cc: stable@vger.kernel.org
> Fixes: c75e5e010fef ("scsi: arm64: dts: rockchip: Add UFS support for RK3576 SoC")
> Reported-by: Quentin Schulz <quentin.schulz@cherry.de>
> Signed-off-by: Alexey Charkov <alchark@gmail.com>
> ---
> This has originally surfaced during the review of UFS patches for U-boot
> at [1], where it was found that the UFS reset line is not requested to be
> configured as GPIO but used as such. This leads in some cases to the UFS
> driver appearing to control device resets, while in fact it is the
> internal controller logic that drives the reset line (perhaps in
> unexpected ways).
> 
> Thanks Quentin Schulz for spotting this issue.
> 
> [1] https://lore.kernel.org/u-boot/259fc358-f72b-4a24-9a71-ad90f2081335@cherry.de/
> ---
>   arch/arm64/boot/dts/rockchip/rk3576-pinctrl.dtsi | 7 +++++++
>   arch/arm64/boot/dts/rockchip/rk3576.dtsi         | 2 +-
>   2 files changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/boot/dts/rockchip/rk3576-pinctrl.dtsi b/arch/arm64/boot/dts/rockchip/rk3576-pinctrl.dtsi
> index 0b0851a7e4ea..20cfd3393a75 100644
> --- a/arch/arm64/boot/dts/rockchip/rk3576-pinctrl.dtsi
> +++ b/arch/arm64/boot/dts/rockchip/rk3576-pinctrl.dtsi
> @@ -5228,6 +5228,13 @@ ufs_rst: ufs-rst {
>   				/* ufs_rstn */
>   				<4 RK_PD0 1 &pcfg_pull_none>;
>   		};
> +
> +		/omit-if-no-ref/
> +		ufs_rst_gpio: ufs-rst-gpio {
> +			rockchip,pins =
> +				/* ufs_rstn */
> +				<4 RK_PD0 RK_FUNC_GPIO &pcfg_pull_none>;

The SoC default is pull-down according to the TRM. Can you check please? 
For example, the Rock 4D doesn't seem to have a hardware pull-up or 
pull-down on the line and the UFS module only seems to have a debouncer 
(capacitor between the line and ground). So except if the chip itself 
has a PU/PD, this may be an issue?

Cheers,
Quentin