[PATCH v1 0/3] mmc: dw_mmc-rockchip: Add stability quirk for NanoPi R76S

[Shawn Lin]

在 2026/01/12 星期一 9:32, Shawn Lin 写道:
> 在 2026/01/10 星期六 9:07, Marco Schirrmeister 写道:
>> This series addresses a microSD stability issue on the FriendlyElec
>> NanoPi R76S (RK3576). The board currently suffers from a 400kHz
>> retuning loop when the controller attempts to enter runtime-suspend
>> during idle periods.
>>
>> Evidence of the failure in dmesg:
>> [Fri Jan  2 01:28:02 2026] mmc_host mmc1: Bus speed (slot 0) = 400000Hz
>> [Fri Jan  2 01:28:03 2026] mmc_host mmc1: Bus speed (slot 0) = 
>> 198000000Hz
>> [Fri Jan  2 01:28:03 2026] dwmmc_rockchip 2a310000.mmc: Successfully 
>> tuned phase to 233
>> [Fri Jan  2 01:28:04 2026] mmc_host mmc1: Bus speed (slot 0) = 400000Hz
>>
> 
> Does this problem happen with all microSDs or just *a* microSD per
> your description?
> Have you ever tried to disable SDR104 support?
> 

A quick update.

I found several problems on RK3576 for supporting sd cards. I wondered
how all upstream RK3576 boards claiming SD support work? Anyway, I sent
a series to the list[1], not sure if it fixes the problem you faced, but
these should be the right patches you should have a try.


[1]https://lore.kernel.org/linux-rockchip/1768189768-96333-1-git-send-email-shawn.lin@rock-chips.com/T/#t

>> Testing confirmed that the issue can be manually addressed by
>> disabling runtime PM via sysfs:
>> echo on > /sys/devices/platform/soc/2a310000.mmc/power/control
>>
>> I experimented with various changes in the Device Tree, including
>> lowering the bus frequency and attempting to keep the power domains
>> active, but nothing stopped the retuning loop.
>> The issue only went away when I forced the controller to stay active
>> by disabling the runtime power management.
>>
>> This quirk is the only way I have found to keep the SDR104 link from
>> crashing on the NanoPi R76S, I am open to suggestions if there is
>> a better way to handle this in the driver or the DTS.
>>
>> Marco Schirrmeister (3):
>>    dt-bindings: mmc: rockchip-dw-mshc: add rockchip,disable-runtime-pm
>>    mmc: host: dw_mmc-rockchip: add rockchip,disable-runtime-pm quirk
>>    arm64: dts: rockchip: add stability quirk to NanoPi R76S
>>
>>   .../bindings/mmc/rockchip-dw-mshc.yaml        |  8 ++++++
>>   .../boot/dts/rockchip/rk3576-nanopi-r76s.dts  |  1 +
>>   drivers/mmc/host/dw_mmc-rockchip.c            | 25 ++++++++++++++++---
>>   3 files changed, 31 insertions(+), 3 deletions(-)
>>
> 
>