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

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 [off-list ref] wrote:

Hi,

On Tue, Aug 23, 2022 at 4:53 AM Heiko Stübner [off-list ref] wrote:

quoted

Am Montag, 22. August 2022, 09:41:39 CEST schrieb Jensen Huang:

quoted

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 <redacted>

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

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