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Message-ID: <084a860a77f18aaafcda4b223eec4fdcd96e75c9.camel@pengutronix.de>
Subject: Re: [PATCH RESEND 10/17] drm/spacemit: add Saturn DPU KMS pipeline
From: Philipp Zabel
To: codykang.hk@gmail.com, David Airlie , Simona Vetter
, Maarten Lankhorst ,
Maxime Ripard , Thomas Zimmermann
, Rob Herring , Krzysztof Kozlowski
, Conor Dooley , Yixun Lan
, Vinod Koul , Neil Armstrong
, Haylen Chu , Michael
Turquette , Stephen Boyd ,
Brian Masney , Paul Walmsley , Palmer
Dabbelt , Albert Ou , Alexandre
Ghiti
Cc: dri-devel@lists.freedesktop.org, linux-riscv@lists.infradead.org,
devicetree@vger.kernel.org, spacemit@lists.linux.dev,
linux-kernel@vger.kernel.org, linux-phy@lists.infradead.org,
linux-clk@vger.kernel.org
Date: Mon, 27 Jul 2026 09:35:38 +0200
In-Reply-To: <20260725-k3-display-v1-10-6de34d80e86c@gmail.com>
References: <20260725-k3-display-v1-0-6de34d80e86c@gmail.com>
<20260725-k3-display-v1-10-6de34d80e86c@gmail.com>
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On Sa, 2026-07-25 at 00:51 -0400, Cody Kang via B4 Relay wrote:
> From: Cody Kang
>=20
> Add the atomic KMS implementation on top of the hardware backend: one
> CRTC and one primary plane per DPU instance. atomic_check validates
> the plane rectangle 1:1 against the mode and sizes the per-channel FBC
> line buffer; atomic commit builds the cmdlist batches, maps the
> framebuffer through the DMMU and arms the cfg-ready handshake, with
> vblank events driven from the DPU interrupt.
>=20
> Signed-off-by: Cody Kang
> ---
> drivers/gpu/drm/spacemit/spacemit_crtc.c | 815 +++++++++++++++++++++++=
++++++
> drivers/gpu/drm/spacemit/spacemit_planes.c | 376 +++++++++++++
> 2 files changed, 1191 insertions(+)
>=20
> diff --git a/drivers/gpu/drm/spacemit/spacemit_crtc.c b/drivers/gpu/drm/s=
pacemit/spacemit_crtc.c
> new file mode 100644
> index 000000000000..b75ff6320501
> --- /dev/null
> +++ b/drivers/gpu/drm/spacemit/spacemit_crtc.c
> @@ -0,0 +1,815 @@
[...]
> +/*
> + * The assert and deassert orders are not mirror images: the hardware wa=
nts
> + * these.
> + */
> +static void dpu_reset_assert(struct device *dev, const char *name,
> + struct reset_control *rstc)
> +{
> + int ret =3D reset_control_assert(rstc);
> +
> + if (ret)
> + dev_warn(dev, "failed to assert %s reset: %d\n", name, ret);
> +}
> +
> +static void dpu_reset_deassert(struct device *dev, const char *name,
> + struct reset_control *rstc)
> +{
> + int ret =3D reset_control_deassert(rstc);
> +
> + if (ret)
> + dev_warn(dev, "failed to deassert %s reset: %d\n", name, ret);
> +}
> +
> +static int dpu_pm_suspend(struct device *dev)
> +{
> + struct spacemit_drm_private *priv =3D dev_get_drvdata(dev);
> + struct spacemit_crtc *a_crtc =3D priv->a_crtc;
> +
> + /*
> + * Assert before gating: a reset asserted into an already-gated block
> + * has no clock edges to propagate on and leaves the register file
> + * untouched.
> + */
> + dpu_reset_assert(dev, "lcd", a_crtc->lcd_reset);
> + dpu_reset_assert(dev, "esc", a_crtc->esc_reset);
> + dpu_reset_assert(dev, "mclk", a_crtc->mclk_reset);
It looks like these three are mirrored, and could be handled by
reset_control_bulk_assert/deassert().
> + dpu_reset_assert(dev, "aclk", a_crtc->aclk_reset);
> + dpu_reset_assert(dev, "dsc", a_crtc->dsc_reset);
> + usleep_range(10000, 20000);
> +
> + if (a_crtc->core && a_crtc->core->disable_clk)
> + a_crtc->core->disable_clk(a_crtc);
> +
> + return 0;
> +}
> +
> +static int dpu_pm_resume(struct device *dev)
> +{
> + struct spacemit_drm_private *priv =3D dev_get_drvdata(dev);
> + struct spacemit_crtc *a_crtc =3D priv->a_crtc;
> +
> + dpu_reset_deassert(dev, "mclk", a_crtc->mclk_reset);
> + dpu_reset_deassert(dev, "esc", a_crtc->esc_reset);
> + dpu_reset_deassert(dev, "lcd", a_crtc->lcd_reset);
> + dpu_reset_deassert(dev, "aclk", a_crtc->aclk_reset);
> + dpu_reset_deassert(dev, "dsc", a_crtc->dsc_reset);
> +
> + if (a_crtc->core && a_crtc->core->enable_clk)
> + a_crtc->core->enable_clk(a_crtc);
> +
> + return 0;
> +}
regards
Philipp