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

[Jensen Huang]

Hi,

Sorry for sending an email in HTML format.

I realized that only some devices may be affected, so I considered
modifying rk3399-nanopi4.dtsi only,
but other boards without external pull-down should still need this patch.


BR,
Jensen

On Tue, Aug 23, 2022 at 10:13 PM Doug Anderson <dianders at chromium.org> wrote:
>
> Hi,
>
> On Tue, Aug 23, 2022 at 4:53 AM Heiko Stübner <heiko at sntech.de> 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 at friendlyarm.com>
> >
> > 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