Messages in this thread | | | Subject | Re: [PATCH] ARM: Keystone: Introduce Kconfig option to compile in typical Keystone features | From | Santosh Shilimkar <> | Date | Wed, 1 Jun 2016 16:26:20 -0700 |
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On 6/1/2016 3:31 PM, Arnd Bergmann wrote: > On Wednesday, June 1, 2016 4:31:54 PM CEST Nishanth Menon wrote: >> Introduce ARCH_KEYSTONE_TYPICAL which is common for all Keystone >> platforms. This is particularly useful when custom optimized defconfig >> builds are created for Keystone architecture platforms. >> >> An example of the same would be a sample fragment ks_only.cfg: >> http://pastebin.ubuntu.com/16904991/ - This prunes all arch other than >> keystone and any options the other architectures may enable. >> >> git clean -fdx && git reset --hard && \ >> ./scripts/kconfig/merge_config.sh -m \ >> ./arch/arm/configs/multi_v7_defconfig ~/tmp/ks_only.cfg &&\ >> make olddefconfig >> >> The above unfortunately will disable options necessary for KS2 boards >> to boot to the bare minimum initramfs. >> >> Hence the "KEYSTONE_TYPICAL" option is designed similar to commit 8d9166b519fd >> ("omap2/3/4: Add Kconfig option to compile in typical omap features") >> that can be enabled for most boards keystone platforms >> without needing to rediscover these in defconfig all over again - >> examples include multi_v7_defconfig base and optimizations done on top >> of them for keystone platform. > > I'd rather remove the option for OMAP as well, it doesn't really fit in with > how we do things for other platforms, and selecting a lot of other Kconfig > symbols tends to cause circular dependencies. > Yes.
>> >> NOTE: the alternative is to select the configurations under >> ARCH_KEYSTONE. However, that would fail multi_v7 builds on ARM >> variants that dont work with LPAE. > > Please no arbitrary selects from the platform. > >> Cc: Bill Mills <wmills@ti.com> >> Cc: Murali Karicheri <m-karicheri2@ti.com> >> Cc: Grygorii Strashko <grygorii.strashko@ti.com> >> Cc: Tero Kristo <t-kristo@ti.com> >> Cc: Lokesh Vutla <lokeshvutla@ti.com> >> Signed-off-by: Nishanth Menon <nm@ti.com> >> --- >> >> Based on: next-20160601 >> >> Tested for basic initramfs boot for K2HK/K2G platforms with the >> http://pastebin.ubuntu.com/16904991/ fragment + multi_v7_defconfig >> >> Side note on LPAE: >> For our current device tree and u-boot, LPAE is mandatory to bootup >> for current Keystone boards - but this is not a SoC requirement, >> booting without LPAE/HIGHMEM results in non-coherent DDR accesses. > > This sounds like a regression, I thought we had this working when > keystone was initially merged and we got both the coherent and > non-coherent mode working with the same DT. > Yes and it works. The coherent memory space itself is beyond 4GB so I don't understand a requirement of having coherent memory without LPAE.
>> Currently: >> - U-Boot assumes that lpae is always enabled in kennel and updates the >> DT memory node with higher addresses. Because of which you are not >> detecting any memory without lpae and kernel crashed very early, hence >> no prints. So, make mem_lpae env setting as 0 in U-boot. > > We could work around this in the kernel by detecting the faulty u-boot > behavior and fixing up the addresses in an early platform callback. > U-boot is already doing that and I don't see any issue with it.
>> - DT also assumes that lpae is always enabled, and always asks for >> dma-address translation for higher addresses to lower addresses. >> Just delete the "dma-ranges" property or create a one-on-one mapping >> like dma-ranges = <0x80000000 0x0 0x80000000 0x80000000> > > This may be a bit trickier, I think originally keystone ignored the > dma-ranges property and hacked up its own offset by adding a magic > constant to the dma address using a bus notifier. We probably don't > want to bring that hack back, but maybe we can come up with another > solution. > I don't think we should go on this path ever. U-boot should modify this parameter as done previously.
Regards, Santosh
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