From: Troy Mitchell <troy.mitchell@linux.spacemit.com>
To: Vivian Wang <wangruikang@iscas.ac.cn>,
Linus Walleij <linusw@kernel.org>,
Bartosz Golaszewski <brgl@kernel.org>,
Yixun Lan <dlan@gentoo.org>, Alex Elder <elder@riscstar.com>
Cc: Bartosz Golaszewski <brgl@bgdev.pl>,
linux-gpio@vger.kernel.org, linux-riscv@lists.infradead.org,
spacemit@lists.linux.dev, linux-kernel@vger.kernel.org,
Troy Mitchell <troy.mitchell@linux.spacemit.com>
Subject: Re: [PATCH] gpio: spacemit-k1: Use PDR for pin direction, not SDR/CDR
Date: Wed, 28 Jan 2026 17:32:37 +0800 [thread overview]
Message-ID: <85EFBB88D70FB64F+aXnXtS35RG_U6MeC@kernel.org> (raw)
In-Reply-To: <20260127-gpio-spacemit-k1-pdr-v1-1-bb868a517dbc@iscas.ac.cn>
On Tue, Jan 27, 2026 at 10:58:49AM +0800, Vivian Wang wrote:
> On the SpacemiT GPIO controller, the direction control register PDR is
> readable and writable [1]. Therefore, implement direction control by
> using PDR as dirout, and don't mark it as unreadable.
>
> The original implementation, using SDR as dirout and CDR as dirin, is
> not actually a supported configuration by gpio-mmio. The hardware
> supports changing the direction of some pins atomically by writing a
> value with the corresponding bits set to SDR (set as output) or to CDR
> (set as input). However, gpio-mmio does not actually handle this.
>
> Using only PDR as dirout to match the expectations of gpio-mmio. This
> also allows us to avoid clobbering potentially important GPIO direction
> configurations set by pre-Linux boot stages.
>
> Found while trying to add PCIe support to OrangePi RV2, where the
> regulator (controlled by GPIO 116) turns off on boot while some other
> GPIO pin in the same bank is touched, which is not desirable.
>
> Link: https://developer.spacemit.com/documentation?token=Rn9Kw3iFHirAMgkIpTAcV2Arnkf#18.4-gpio # [1]
> Fixes: d00553240ef8 ("gpio: spacemit: add support for K1 SoC")
> Signed-off-by: Vivian Wang <wangruikang@iscas.ac.cn>
> ---
> Tested on K1 only - help with K3 testing would be appreciated.
Confirmed that PDR is also R/W on K3. Thanks!
Reviewed-by: Troy Mitchell <troy.mitchell@linux.spacemit.com>
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next prev parent reply other threads:[~2026-01-28 9:33 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-01-27 2:58 [PATCH] gpio: spacemit-k1: Use PDR for pin direction, not SDR/CDR Vivian Wang
2026-01-28 9:32 ` Troy Mitchell [this message]
2026-01-28 9:41 ` Bartosz Golaszewski
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