[PATCH v2] pmdomain: imx: Fix i.MX8MP VC8000E power up sequence

[PATCH v2] pmdomain: imx: Fix i.MX8MP VC8000E power up sequence

[Peng Fan (OSS)]

From: Peng Fan <peng.fan@nxp.com>

Per errata[1]:
ERR050531: VPU_NOC power down handshake may hang during VC8000E/VPUMIX
power up/down cycling.
Description: VC8000E reset de-assertion edge and AXI clock may have a
timing issue.
Workaround: Set bit2 (vc8000e_clk_en) of BLK_CLK_EN_CSR to 0 to gate off
both AXI clock and VC8000E clock sent to VC8000E and AXI clock sent to
VPU_NOC m_v_2 interface during VC8000E power up(VC8000E reset is
de-asserted by HW)

Add a bool variable is_errata_err050531 in
'struct imx8m_blk_ctrl_domain_data' to represent whether the workaround
is needed. If is_errata_err050531 is true, first clear the clk before
powering up gpc, then enable the clk after powering up gpc.

While at here, using imx8mm_vpu_power_notifier() is wrong, as it ungates
the VPU clocks to provide the ADB clock, which is necessary on i.MX8MM,
but on i.MX8MP there is a separate gate (bit 3) for the NoC. So add
imx8mp_vpu_power_notifier() for i.MX8MP.

[1] https://www.nxp.com/webapp/Download?colCode=IMX8MP_1P33A

Fixes: a1a5f15f7f6cb ("soc: imx: imx8m-blk-ctrl: add i.MX8MP VPU blk ctrl")
Cc: stable@vger.kernel.org
Signed-off-by: Peng Fan <peng.fan@nxp.com>
---
Changes in v2:
- Add errata link in commit message
- Add comment for is_errata_err050531
- Link to v1: https://lore.kernel.org/r/20260128-imx8mp-vc8000e-pm-v1-1-6c171451c732@nxp.com
---
 drivers/pmdomain/imx/imx8m-blk-ctrl.c | 45 +++++++++++++++++++++++++++++++++--
 1 file changed, 43 insertions(+), 2 deletions(-)

diff --git a/drivers/pmdomain/imx/imx8m-blk-ctrl.c b/drivers/pmdomain/imx/imx8m-blk-ctrl.c
index 19e992d2ee3b845bc9382bcd494a5d96f9c6ac44..1cd0a22ce3e533358dd7449da9989162b36c5fe6 100644
--- a/drivers/pmdomain/imx/imx8m-blk-ctrl.c
+++ b/drivers/pmdomain/imx/imx8m-blk-ctrl.c
@@ -54,6 +54,15 @@ struct imx8m_blk_ctrl_domain_data {
 	 * register.
 	 */
 	u32 mipi_phy_rst_mask;
+
+	/*
+	 * VC8000E reset de-assertion edge and AXI clock may have a timing issue.
+	 * Workaround: Set bit2 (vc8000e_clk_en) of BLK_CLK_EN_CSR to 0 to gate off
+	 * both AXI clock and VC8000E clock sent to VC8000E and AXI clock sent to
+	 * VPU_NOC m_v_2 interface during VC8000E power up(VC8000E reset is
+	 * de-asserted by HW)
+	 */
+	bool is_errata_err050531;
 };
 
 #define DOMAIN_MAX_CLKS 4
@@ -108,7 +117,11 @@ static int imx8m_blk_ctrl_power_on(struct generic_pm_domain *genpd)
 		dev_err(bc->dev, "failed to enable clocks\n");
 		goto bus_put;
 	}
-	regmap_set_bits(bc->regmap, BLK_CLK_EN, data->clk_mask);
+
+	if (data->is_errata_err050531)
+		regmap_clear_bits(bc->regmap, BLK_CLK_EN, data->clk_mask);
+	else
+		regmap_set_bits(bc->regmap, BLK_CLK_EN, data->clk_mask);
 
 	/* power up upstream GPC domain */
 	ret = pm_runtime_get_sync(domain->power_dev);
@@ -117,6 +130,9 @@ static int imx8m_blk_ctrl_power_on(struct generic_pm_domain *genpd)
 		goto clk_disable;
 	}
 
+	if (data->is_errata_err050531)
+		regmap_set_bits(bc->regmap, BLK_CLK_EN, data->clk_mask);
+
 	/* wait for reset to propagate */
 	udelay(5);
 
@@ -514,9 +530,34 @@ static const struct imx8m_blk_ctrl_domain_data imx8mp_vpu_blk_ctl_domain_data[]
 	},
 };
 
+static int imx8mp_vpu_power_notifier(struct notifier_block *nb,
+				     unsigned long action, void *data)
+{
+	struct imx8m_blk_ctrl *bc = container_of(nb, struct imx8m_blk_ctrl,
+						 power_nb);
+
+	if (action == GENPD_NOTIFY_ON) {
+		/*
+		 * On power up we have no software backchannel to the GPC to
+		 * wait for the ADB handshake to happen, so we just delay for a
+		 * bit. On power down the GPC driver waits for the handshake.
+		 */
+
+		udelay(5);
+
+		/* set "fuse" bits to enable the VPUs */
+		regmap_set_bits(bc->regmap, 0x8, 0xffffffff);
+		regmap_set_bits(bc->regmap, 0xc, 0xffffffff);
+		regmap_set_bits(bc->regmap, 0x10, 0xffffffff);
+		regmap_set_bits(bc->regmap, 0x14, 0xffffffff);
+	}
+
+	return NOTIFY_OK;
+}
+
 static const struct imx8m_blk_ctrl_data imx8mp_vpu_blk_ctl_dev_data = {
 	.max_reg = 0x18,
-	.power_notifier_fn = imx8mm_vpu_power_notifier,
+	.power_notifier_fn = imx8mp_vpu_power_notifier,
 	.domains = imx8mp_vpu_blk_ctl_domain_data,
 	.num_domains = ARRAY_SIZE(imx8mp_vpu_blk_ctl_domain_data),
 };

---
base-commit: 81f98c6c88ebd36df93d903bdfd3c8a10a722eef
change-id: 20260128-imx8mp-vc8000e-pm-4278e6d48b54

Best regards,
-- 
Peng Fan <peng.fan@nxp.com>

Re: [PATCH v2] pmdomain: imx: Fix i.MX8MP VC8000E power up sequence

[Peng Fan]

Hi All,

Any comments?

On Sat, Feb 28, 2026 at 09:12:45AM +0800, Peng Fan (OSS) wrote:
>From: Peng Fan <peng.fan@nxp.com>
>
>Per errata[1]:
>ERR050531: VPU_NOC power down handshake may hang during VC8000E/VPUMIX
>power up/down cycling.
>Description: VC8000E reset de-assertion edge and AXI clock may have a
>timing issue.
>Workaround: Set bit2 (vc8000e_clk_en) of BLK_CLK_EN_CSR to 0 to gate off
>both AXI clock and VC8000E clock sent to VC8000E and AXI clock sent to
>VPU_NOC m_v_2 interface during VC8000E power up(VC8000E reset is
>de-asserted by HW)
>

Thanks,
Peng

Re: [PATCH v2] pmdomain: imx: Fix i.MX8MP VC8000E power up sequence

[Daniel Baluta]

On 2/28/26 03:12, Peng Fan (OSS) wrote:
> From: Peng Fan <peng.fan@nxp.com>
>
> Per errata[1]:
> ERR050531: VPU_NOC power down handshake may hang during VC8000E/VPUMIX
> power up/down cycling.
> Description: VC8000E reset de-assertion edge and AXI clock may have a
> timing issue.
> Workaround: Set bit2 (vc8000e_clk_en) of BLK_CLK_EN_CSR to 0 to gate off
> both AXI clock and VC8000E clock sent to VC8000E and AXI clock sent to
> VPU_NOC m_v_2 interface during VC8000E power up(VC8000E reset is
> de-asserted by HW)
>
> Add a bool variable is_errata_err050531 in
> 'struct imx8m_blk_ctrl_domain_data' to represent whether the workaround
> is needed. If is_errata_err050531 is true, first clear the clk before
> powering up gpc, then enable the clk after powering up gpc.
>
> While at here, using imx8mm_vpu_power_notifier() is wrong, as it ungates
> the VPU clocks to provide the ADB clock, which is necessary on i.MX8MM,
> but on i.MX8MP there is a separate gate (bit 3) for the NoC. So add
> imx8mp_vpu_power_notifier() for i.MX8MP.
>
> [1] https://www.nxp.com/webapp/Download?colCode=IMX8MP_1P33A
>
Peng,

Is using imx8mm_vpu_power_notifier wrong no matter on the errata? If so, I think you should fix

that problem first, e.g create a separate patch that fixes the notifier and then add support for the errata. In the future, if the chips with the errata are deprecated we could only revert that given patch. thanks,

Daniel.