Hi Julian, On Wed, Jan 31, 2018 at 07:29:13PM +1100, Julian Calaby wrote: > Hi Maxime, > > On Wed, Jan 31, 2018 at 7:21 PM, Maxime Ripard > <maxime.rip...@free-electrons.com> wrote: > > Hi, > > > > On Mon, Jan 29, 2018 at 10:38:25AM +0000, Andre Przywara wrote: > >> On 29/01/18 09:58, Maxime Ripard wrote: > >> > On Mon, Jan 29, 2018 at 09:44:44AM +0000, Andre Przywara wrote: > >> >> On 29/01/18 08:51, Maxime Ripard wrote: > >> >>> On Mon, Jan 29, 2018 at 01:15:19AM +0000, Andre Przywara wrote: > >> >>>> The existing sun8i-emac driver in U-Boot uses some preliminary > >> >>>> bindings, > >> >>>> which matched our own DTs. Now that the Linux kernel got a driver, > >> >>>> lets > >> >>>> update our probe code to handle those Linux DTs as well. > >> >>>> The first patch adds the missing compatible strings for the pinctrl > >> >>>> drivers, > >> >>>> which is needed for using the sunxi_name_to_gpio() lookup function. > >> >>>> Patch 2/3 updates the pinctrl parser used in the sun8i-emac driver, > >> >>>> to cope > >> >>>> with the new, generic Allwinner pinctrl bindings. > >> >>>> The final patch extends the probe routine in the Ethernet driver to > >> >>>> deal > >> >>>> with both the old and the new bindings. > >> >>> > >> >>> Thanks for posting this > >> >>> > >> >>>> This series allows to copy in the DTs from the latest kernel. > >> >>>> Unfortunately > >> >>>> right now updating the DTs for the H5 and A64 breaks the build, as the > >> >>>> resulting binary (which embeds the DT) gets to large and triggers our > >> >>>> new > >> >>>> image size check. > >> >>> > >> >>> Sigh... > >> >>> > >> >>>> As the H5 and H3 share most of the DT, we can't just update the H3 > >> >>>> DTs either. Hopefully we find some neat trick to work around that. > >> >>> > >> >>> Is it just because of the DT size, or because there's more code? > >> >> > >> >> My impression the code itself is always growing a tiny bit over the > >> >> weeks, but this time around it's really the DT update. > >> >> The current A64 .dtbs in U-Boot are around 8KB, mainline is at 13KB. > >> >> Similar for the H5: going from 9.5KB to 14.5KB. > >> >> > >> >> Since you did a pretty good job already in identifying the code hogs, I > >> >> couldn't find *easy* mitigations over the weekend. > >> >> One possible fix is to remove the second .dtb in the Pine64 case, for > >> >> which I sent a patch Friday night. > >> > > >> > Since the DT is fed to the C preprocessor, we could also put some > >> > #ifdef 0 around the nodes that are never used by U-Boot (like the > >> > clocks, timer, psci, dma, GIC, RTC, RSB, etc.) > >> > >> Well yes, U-Boot itself actually only requires a *tiny* .dtb (I think > >> /aliases, /chosen, the reg of USB and Ethernet). But to be honest I > >> don't want to go there. First it would be a constant churn to keep this > >> up-to-date, > > > > I'm not too worried about the churn, it would be there only for the > > time until we fully migrate to the FAT environment, so one-two release > > now. And we're not syncing the DT very often these days (now that we > > have support for the EMAC and USB that is all U-Boot cares about). > > > >> but more importantly for proper UEFI boot we just reuse U-Boot's > >> .dtb to pass it on to the kernel. That is actually the purpose of > >> this whole exercise. That already works today (at least for A64), > >> but would benefit from some updates. > >> > >> So I would refrain from tinkering with U-Boot's .dtbs. > > > > That sucks :/ > > > >> > This should give us some room. > >> > > >> >> Another thing that stuck out is the sha256 checksum. It's "default y" if > >> >> you have FIT. We need FIT for the SPL loader - but we don't do or need > >> >> the checksum there. > >> >> Some people do FIT loading for the kernel and initrd in U-Boot proper, I > >> >> suppose, but I am not sure how many depend on SHA256 checksums in their > >> >> images. > >> > > >> > I think there was someone (Tom?) that said that it was useful in some > >> > circumstances? > >> > >> Yes, I clearly see that it is *useful*, but I wonder how many people > >> would actually miss it today? We would bring it back once we dumped > >> ENV_IS_IN_MMC, so it's only temporarily. > > > > His words were stronger actually, and he said that we want to keep it. > > > >> I think we can just disable it in some defconfigs, to avoid collateral > >> damage to other boards. > >> If people have a special need, they can always disable the MMC env and > >> enable stuff at their likings, it's just the standard "make > >> .._defconfig; make" process that needs to be fixed with some band-aids > >> for now. > > > > I really don't want to go down the "let's fix each defconfig when we > > find out it broke", this is very likely to be broken with no-one > > noticing. > > > > Is this issue happening when you sync the whole DT, and would it break > > if you just convert the EMAC binding? > > > > Otherwise, we might try to revive the DTC garbage collection of unused > > nodes patches. This would prevent us from using the overlays on such a > > DT, but that doesn't like like an unfair tradeoff. > > Stupid question:
It's not really stupid :) > As I understand it, the boot process is SPL => Full U-Boot => Linux. > > Would it therefore be possible to use a cut-down DT for the SPL (just > the bits it cares about) then use a full one afterwards? The thing is, we're not using the DT for the SPL, and the DT size we're discussing about is the one in the main U-Boot binary. > I'm guessing that the SPL wants to patch the DT we pass to Linux, > would we be able to handle that using overlays? In a "standard" setup (or at least the one you described), U-Boot will patch, or apply the overlay to, the DT provided by Linux, not its own, so even if we prevent the overlay usage on U-Boot's own, the only downside would be that the UEFI case Andre was describing would not work with overlays anymore. Actually, we're not building U-boot's DT with overlay support anyway at the moment, so it's not a regression. Maxime -- Maxime Ripard, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com
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