Re: [PATCH v2 2/6] ARM: dts: bcm283x: Define standard pinctrl groups in the gpio node.
From: Gerd Hoffmann <hidden>
Date: 2016-09-13 06:34:44
Also in:
linux-arm-kernel, lkml
Hi,
quoted
quoted
+ emmc_gpio48: emmc_gpio48 { + brcm,pins = <48 49 50 51 52 53>; + brcm,function = <BCM2835_FSEL_ALT3>; + };Sorry, i didn't notice this before. The naming of these groups suggest 3 muxes for the same eMMC interface. I thought there is a eMMC interface and a SD host interface with different DMA channels.quoted
+ ... + + sdhost_gpio48: sdhost_gpio48 { + brcm,pins = <48 49 50 51 52 53>; + brcm,function = <BCM2835_FSEL_ALT0>; + };I think this incorrect. There is no function ALT0 for these pins, only ALT3.please forget my last 2 comments. According to this page [1] eMMC is selected by ALT3 and sdhost is selected by ALT0. Do you know a reliable source where all muxes for both interface are documented? The datasheet isn't very helpful here.
No, I don't know any source better than the datasheet @ github.
Yes, I tried to double-check things with the sheet too.
IIRC Eric mentioned a while back in some mail or patch that he checked
something for the rpi device tree with non-public docs, not fully sure
though whenever it was emmc/sdhost or something else. But I'm basically
trusting Eric here ...
cheers,
Gerd
PS: This is exactly why I think it us useful to have all those entries
in the dt file even if unused: To serve as documentation.
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