On Thu, Jan 20, 2022 at 7:36 PM Andre Przywara <andre.przyw...@arm.com> wrote: > > On Thu, 20 Jan 2022 19:08:57 +0530 > Jagan Teki <ja...@amarulasolutions.com> wrote: > > Hi, > > > On Tue, Jan 11, 2022 at 6:16 PM Andre Przywara <andre.przyw...@arm.com> > > wrote: > > > > > > On the Allwinner H6 SoC both the SPI0 and the eMMC device share one pin, > > > so cannot be used simultaneously. On Linux this is a showstopper, since > > > only one of them would be able to claim the pin, and the probe order is > > > somewhat random. The DT consequently disables SPI0 in favour of the more > > > useful eMMC. > > > > > > But a comment in the DT actually suggests that this could be reversed by > > > U-Boot, if no eMMC is actually connected. Let's now implement this: > > > When we fix up the device tree before booting a kernel, we iterate over > > > all MMC devices, and check if there is an eMMC device among them. If none > > > can be found, we enable SPI0 instead, to allow Linux access to the SPI > > > flash. > > > > > Since this fixup is not really universally applicable to all boards, > > > let's hide it behind a Kconfig option, and enable it only on the one > > > supported board where this makes sense: the Pine H64. > > > > > > Please note that the SPI functionality is still disabled in U-Boot > > > proper, the pinmux clash affects us too: it would always disable the eMMC > > > and so spoil this algorithm here. > > > > > > Signed-off-by: Andre Przywara <andre.przyw...@arm.com> > > > --- > > > arch/arm/mach-sunxi/Kconfig | 10 ++++++++ > > > board/sunxi/board.c | 50 +++++++++++++++++++++++++++++++++++++ > > > configs/pine_h64_defconfig | 1 + > > > 3 files changed, 61 insertions(+) > > > > > > diff --git a/arch/arm/mach-sunxi/Kconfig b/arch/arm/mach-sunxi/Kconfig > > > index 56ff1e197c..ce66453029 100644 > > > --- a/arch/arm/mach-sunxi/Kconfig > > > +++ b/arch/arm/mach-sunxi/Kconfig > > > @@ -1047,6 +1047,16 @@ config BLUETOOTH_DT_DEVICE_FIXUP > > > The used address is "bdaddr" if set, and "ethaddr" with the LSB > > > flipped elsewise. > > > > > > +config SUNXI_H6_ENABLE_SPIFLASH > > > + bool "Enable H6 SPI flash vs. eMMC enablement" > > > + depends on MACH_SUN50I_H6 > > > + default n > > > + help > > > + Enable this option if you want U-Boot check for an eMMC device > > > + on Allwinner H6 boards, and enable the SPI flash if none is > > > found. > > > + SPI0 and MMC2 share one pin, so cannot coexist in Linux. The > > > + DT prefers eMMC, but if none is used, we can safely enable SPI. > > > > Why we need a separate macro, cannot we check it H6 globally as it SoC > > design? > > This "hack" is board dependent. We don't know if there is a SPI flash or > eMMC in the first place, and this whole concept is weird enough that it > warrants a separate config option. > Probably due to this hardware issue the PineH64 is actually the only board > in mainline that has both SPI flash and eMMC, and I don't want to enable > SPI flash on every eMMC less board. Also it simplifies the code if we can > assume that both DT nodes exist, when that config is enabled. > > Cheers, > Andre > > P.S. Actually I wanted to forgot to mark this one as RFC, as I am not sure > that it's justified. The comment in the mainline DT suggests this > solution, and I was curious what it would take to make it work, as > apparently some people are interested in it.
If it board-specific, better switch to RFC or load the overlay by checking on board specific boot script. Thanks, Jagan.