Messages in this thread | | | From | Vladimir Oltean <> | Subject | Re: [PATCH] arm64: dts: ls1028a: make the eMMC and SD card controllers use fixed indices | Date | Tue, 24 Nov 2020 11:28:22 +0000 |
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On Tue, Nov 24, 2020 at 11:15:19AM +0000, Y.b. Lu wrote: > > > Not matter it's SD card or eMMC card, if it's on esdhc0, use /dev/mmcblk0. > > > Not matter it's SD card or eMMC card, if it's on esdhc1, use /dev/mmcblk1. > > > > With the note here that you can't actually connect an SD card to eSDHC1, > > due to the lack of pins for CD/WP. > > CD/WP is not essential to support SD card. Both SD/eMMC are supported on both eSDHC controllers.
Let's keep that discussion separate. While in theory you might be right, I think the real-life complications associated with connecting an eMMC to eSDHC0 and an SD card to eSDHC1 will make everyone avoid that. So in practice they are still single-purpose.
> > But it is also natural for a customer to define the indices according to > > their schematics and what they use. If, say, there is a board that only > > uses eMMC, I would expect that for the lay person, no one would even bat > > an eye if that was called /dev/mmcblk0. Whereas, if it was called > > /dev/mmcblk1 (and there was no /dev/mmcblk0 in the system), maybe you'd > > have to come up with some explanations which could be avoided. > > To make a product friendly to users, it makes sense to define different alias for controller in board dts. > But it's not the reason to remove the default/natural alias in soc dtsi for two controllers. > What needs to be done after removing them? Add the same to all other board files?
Yes. In fact, this is also the reason why we prefer to have: /soc { esdhc: mmc@2140000 { status = "disabled"; }; }; in fsl-ls1028a.dtsi and &esdhc { status = "okay"; }; in fsl-ls1028a-rdb.dts and not the other way around:
/soc { esdhc: mmc@2140000 { status = "okay"; }; }; in fsl-ls1028a.dtsi and &esdhc { status = "disabled"; }; in fsl-ls1028a-rdb.dts
So, in line with that, I think that the entity that enables the node should also define the alias.
It's weird to use /delete-property/ if it can be avoided.
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