arm64: dts: adi: sc846-som: eMMC (mmc0) fails with "Internal clock never stabilised"

[ozan956]

Seems like eMMC is not working.

First I added this node to enable it:

&mmc0 {
	bus-width = <8>;
	non-removable;
	no-sd;
	no-sdio;
	status = "okay";
};

Then I got this:

[    6.704590] mmc0: Internal clock never stabilised.
[    6.709283] mmc0: sdhci: ============ SDHCI REGISTER DUMP ===========
[    6.716261] mmc0: sdhci: Sys addr:  0x00000000 | Version:  0x00000005
[    6.723041] mmc0: sdhci: Blk size:  0x00000000 | Blk cnt:  0x00000000
[    6.729727] mmc0: sdhci: Argument:  0x00000000 | Trn mode: 0x00000000
[    6.736415] mmc0: sdhci: Present:   0x03f700f0 | Host ctl: 0x00000000
[    6.743095] mmc0: sdhci: Power:     0x0000000f | Blk gap:  0x00000000
[    6.749796] mmc0: sdhci: Wake-up:   0x00000000 | Clock:    0x00007181
[    6.756478] mmc0: sdhci: Timeout:   0x00000000 | Int stat: 0x00000000
[    6.763156] mmc0: sdhci: Int enab:  0x00ff1003 | Sig enab: 0x00ff1003
[    6.769841] mmc0: sdhci: ACmd stat: 0x00000000 | Slot int: 0x00000000
[    6.776524] mmc0: sdhci: Caps:      0x256ec88a | Caps_1:   0x0800ab77
[    6.783316] mmc0: sdhci: Cmd:       0x00000000 | Max curr: 0x00000000
[    6.789987] mmc0: sdhci: Resp[0]:   0x00000000 | Resp[1]:  0x00000000
[    6.796729] mmc0: sdhci: Resp[2]:   0x00000000 | Resp[3]:  0x00000000
[    6.803409] mmc0: sdhci: Host ctl2: 0x00000000
[    6.808093] mmc0: sdhci: ADMA Err:  0x00000000 | ADMA Ptr: 0x00000000
[    6.814774] mmc0: sdhci: ============================================

It just keeps lopping for some amount of time. It can not be initialized.

Can you please enable the eMMC properly and have some tests running on it then have a PR?

[ozan956]

Maybe @sipraga can help since I remember he also worked on eMMC but not sure whether it was 598 or 846.

[sipraga]

@ozan956 I haven't tested SC846. But on SC598 this error (failed to stabilize internal clock) occurs when the EMMC_TIMER_CMQ clock is unavailable. I have a draft PR here, but I'm waiting for internal clarification on what the EMSI block actually needs clock-wise: #3487

For SC846 there's no such clock at all - only the MSHC clock - but it still sounds like a clock is missing.

Did you try with clk_ignore_unused?

Maybe the rate is wrong?

Could also be an issue in the clock driver, failing to enable MSHC.

[sipraga]

Might also be some muxes you have to configure to reach the eMMC. But I don't think you get this error just because external pins are connected to junk.

[qasim-ijaz]

Managed to fix this error, seems this issue is related to the EMMC timer which needs to be enabled + a divider value needs to be set for it's clock. For now I have set 1, but have contacted the apps team for more details on what it should be. Another error appears once this is fixed:

mmc0: Failed to initialize a non-removable card

This seems to be related to additional EMSI0 specific configuration. I am currently investigating the PHY initialisation/configuration.