Re: [PATCH 1/3] arm64: dts: ti: iot2050: Flip mmc device ordering on Advanced devices

On 22:17-20210907, Aswath Govindraju wrote:

Hi Nishanth,

On 07/09/21 9:05 pm, Nishanth Menon wrote:

quoted

On 17:30-20210907, Jan Kiszka wrote:

quoted

On 07.09.21 17:27, Nishanth Menon wrote:

quoted

On 17:20-20210907, Jan Kiszka wrote:

quoted

On 07.09.21 17:13, Nishanth Menon wrote:

quoted

On 16:22-20210907, Jan Kiszka wrote:

quoted

From: Jan Kiszka <jan.kiszka@siemens.com>

This ensures that the SD card will remain mmc0 across Basic and Advanced
devices, also avoiding surprises for users coming from the downstream
kernels.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
---
 arch/arm64/boot/dts/ti/k3-am6548-iot2050-advanced.dts | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/arm64/boot/dts/ti/k3-am6548-iot2050-advanced.dts b/arch/arm64/boot/dts/ti/k3-am6548-iot2050-advanced.dts
index ec9617c13cdb..d1d5278e0b94 100644
--- a/arch/arm64/boot/dts/ti/k3-am6548-iot2050-advanced.dts
+++ b/arch/arm64/boot/dts/ti/k3-am6548-iot2050-advanced.dts

@@ -18,6 +18,11 @@ / {
 	compatible = "siemens,iot2050-advanced", "ti,am654";
 	model = "SIMATIC IOT2050 Advanced";
 
+	aliases {
+		mmc0 = &sdhci1;
+		mmc1 = &sdhci0;
+	};

Should we do this at SoC level?

Well, I wouldn't mind - but that would also impact your EVMs. For us,
this is fine as we are coming from that ordering above with our
downstream kernel/dts.

I think it'd probably be a welcome change. overall we've standardized on
partuuid.

Yeah, it's more about "dd if=emmc.img of=/dev/mmcblk1 - damn, the wrong
one again."

Let me know what you prefer, and I'll update my patch.

Lets do it at SoC level. I will follow it up with a patch for other K3
SoCs as well.


Unless someone has a strong opinion on this approach - if so, speak up
with reasons.

Making this change in SoC level for all K3 devices would force changes
to be made in U-Boot too, for consistency. In U-Boot, a major change
would be required in the environment variables to support this. As I
don't see any functional advantage by making this change, I feel that
this change would make things more confusing for users already using the
K3 devices. At present, the ordering is consistent across all the K3
devices, I feel that keeping it the same way would be better.

As for making changes only on IoT boards, if it is okay to have the
ordering changed between U-Boot and kernel, I don't see any problem
making this change in kernel alone.

arch/arm64/boot/dts/ti/k3-am65.dtsi has no ordering. u-boot is supposed
to copy from kernel the dtsi files as is. I think having mmc aliases in
kernel is a good thing as we do regard kernel as the canonical dts
source.

If you are suggesting we flip things so that mmc0 is sdhci0 and mmc1 is
sdhci1 -  that might be a valid suggestion - Jan, do you see a problem
in having consistency here (flip the aliases)?


-- 
Regards,
Nishanth Menon
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