Re: [PATCH 0/3] arm64: dts: qcom: sm8x50: Enable UHS-I SDR50 and SDR104 SD card modes

[Vladimir Zapolskiy <vladimir.zapolskiy@linaro.org>]

Hi Val,

On 11/26/25 18:14, Val Packett wrote:
> Hi,
> 
> On 11/25/25 10:20 PM, Vladimir Zapolskiy wrote:
>> The reported problem of some non-working UHS-I speed modes on SM8450
>> originates in commit 0a631a36f724 ("arm64: dts: qcom: Add device tree
>> for Sony Xperia 1 IV"), and then it was spread to all SM8450 powered
>> platforms by commit 9d561dc4e5cc ("arm64: dts: qcom: sm8450: disable
>> SDHCI SDR104/SDR50 on all boards").
>>
>> The tests show that the rootcause of the problem was related to an
>> overclocking of SD cards, and it's fixed later on by commit a27ac3806b0a
>> ("clk: qcom: gcc-sm8450: Use floor ops for SDCC RCGs").
>>
>> Due to a missed setting of an appropriate SDCC clock operations in
>> platform GCC driver the workaround of dropping SD card speeds from UHS-I
>> to high speed was spread to SM8550 and SM8650 platforms, and since
>> the fixes in the clock controller drivers are ready [1], it should be
>> safe to remove the speed mode restrictions from SM8450, SM8550 and
>> SM8650 platforms.
>> [..]
> 
> I see you have tested with dd on the raw block device, but have you
> tested hotplugging SD cards that have partition tables and filesystems
> on them?

the test results given in the commit message are for demonstation purpose,
the test do serve right the same purpose of performing I/O reading from
an SD card as reading a partition table.

An important point is that if there are some issues with a filesystem on
SD card, it just lacks a justification of "forbidding SDR104/SDR50 due
broken SDHC hardware".

> We have this kind of issue on Hamoa where we get I/O errors early, right
> after the card is inserted and the partition table / filesystem headers
> are being read:

Hamoa is X1E80100, is it right? Unfortunately I can not test my set of
SD cards including one Transcend UHS-I SDR104 speed mode SD card on this
particular hardware.

> [  714.057106] mmc0: new UHS-I speed SDR104 SDXC card at address 0001
> [  714.060567] mmcblk0: mmc0:0001 EC2QT 59.6 GiB
> [  714.503873] I/O error, dev mmcblk0, sector 0 op 0x0:(READ) flags 0x0
> phys_seg 1 prio class 2
> [  714.505660] Buffer I/O error on dev mmcblk0, logical block 0, async
> page read
> [  714.513632] I/O error, dev mmcblk0, sector 0 op 0x0:(READ) flags 0x0
> phys_seg 1 prio class 2
> [  714.516469] Buffer I/O error on dev mmcblk0, logical block 0, async
> page read
> [  714.516512]  mmcblk0: unable to read partition table
> 
> and b1f856b1727c ("mmc: sdhci-msm: Avoid early clock doubling during
> HS400 transition") did not help..
> 

I've checked that this particular change [1], and it's unlikely that it
has an impact on the issue reported above due to the fact that the
problem is reported against an UHS-I SDR104 SD card, and the fix does
not touch this mode. So, it's kind of expected, and for further analysis
I need more information.

Note what is the originally reported problem, which workaround is supposed
to be reverted now:

9d561dc4e5cc ("arm64: dts: qcom: sm8450: disable SDHCI SDR104/SDR50 on all boards"):

       mmc0: card never left busy state
       mmc0: error -110 whilst initialising SD card

This is very different from your fault report, and this is fixed by
my recent changes in the SM8x50 GCC drivers, and this one series
setteles the fix.

[1] https://lore.kernel.org/linux-mmc/20251114082824.3825501-1-sarthak.garg@oss.qualcomm.com/

-- 
Best wishes,
Vladimir