Re: [PATCH] arm64: dts: rockchip: add enable-strobe-pulldown to emmc phy on rk3399

[Doug Anderson]

Hi,

On Tue, Aug 23, 2022 at 4:53 AM Heiko Stübner <heiko@xxxxxxxxx> wrote:
>
> Am Montag, 22. August 2022, 09:41:39 CEST schrieb Jensen Huang:
> > Internal pull-down for strobe line (GRF_EMMCPHY_CON2[9]) was disabled
> > by commit 8b5c2b45b8f0, which causes I/O error in HS400 mode.
> >
> > Tested on NanoPC-T4.
> >
> > Fixes: 8b5c2b45b8f0 ("phy: rockchip: set pulldown for strobe line in dts")
> > Signed-off-by: Jensen Huang <jensenhuang@xxxxxxxxxxxxxxx>
>
> ok, so this looks like it restores previous functionality.
>
> I'm just wondering as the "offending" patch is from 2020, why this
> only turns up now. Any ideas?

Ah, I see. So before the offending patch we used to just leave the
pull state at whatever the default was when the kernel was booted.
After the offending patch we chose a default.

On kevin I see an external pull down on this line. Enabling both the
internal and external is probably not a huge deal, it'll just affect
the strength of the pull.

On bob I _think_ the external pull down is also stuffed.

...so I guess that would explain why it didn't cause a problem for at
least those two boards?

-Doug