[RFC] power: imx8m-power-domain: Add delay to align with kernel driver

[RFC] power: imx8m-power-domain: Add delay to align with kernel driver

[Fabio Estevam]

From: Fabio Estevam <festevam@denx.de>

In the imx8m power domain kernel driver, there is an extra udelay(5)
prior to requesting the domain to power up:

https://github.com/torvalds/linux/blob/v6.3/drivers/soc/imx/gpcv2.c#L347-L375

Haven't observed any issues due to the lack of this delay
in U-Boot, but better to align it with the driver implementation.

Signed-off-by: Fabio Estevam <festevam@denx.de>
---
Marking it as RFC for now, to try to get some feedback first.

Thanks

 drivers/power/domain/imx8m-power-domain.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/power/domain/imx8m-power-domain.c b/drivers/power/domain/imx8m-power-domain.c
index 145f6ec0cd32..df5d7d695621 100644
--- a/drivers/power/domain/imx8m-power-domain.c
+++ b/drivers/power/domain/imx8m-power-domain.c
@@ -338,6 +338,9 @@ static int imx8m_power_domain_on(struct power_domain *power_domain)
 		}
 	}
 
+	/* delay for reset to propagate */
+	udelay(5);
+
 	if (domain->bits.pxx) {
 		/* request the domain to power up */
 		setbits_le32(base + regs->pup, domain->bits.pxx);
-- 
2.34.1

Re: [RFC] power: imx8m-power-domain: Add delay to align with kernel driver

[Marek Vasut]

On 4/28/23 21:52, Fabio Estevam wrote:
> From: Fabio Estevam <festevam@denx.de>
> 
> In the imx8m power domain kernel driver, there is an extra udelay(5)
> prior to requesting the domain to power up:
> 
> https://github.com/torvalds/linux/blob/v6.3/drivers/soc/imx/gpcv2.c#L347-L375
> 
> Haven't observed any issues due to the lack of this delay
> in U-Boot, but better to align it with the driver implementation.
> 
> Signed-off-by: Fabio Estevam <festevam@denx.de>

Reviewed-by: Marek Vasut <marex@denx.de>