Hi Andre, On Thu, Jan 20, 2022 at 8:06 PM Jagan Teki <ja...@amarulasolutions.com> wrote: > > 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.
Anything about this? Jagan.
