On Fri, Jul 07, 2017 at 05:00:50PM +0200, Jean-Jacques Hiblot wrote: > > > On 07/07/2017 16:30, Tom Rini wrote: > >On Fri, Jul 07, 2017 at 01:44:39PM +0200, Jean-Jacques Hiblot wrote: > > > >>u-boot can be embedded within a FIT image with multiple DTBs. It then > >>selects at run-time which one is best suited for the platform. > >>Use the same principle here for the SPL: put the DTBs in a FIT image, > >>compress it (LZO, GZIP, or no compression) and append it at the end of the > >>SPL. > >> > >>Signed-off-by: Jean-Jacques Hiblot <[email protected]> > >>--- > >> > >>The impact in terms of boot time is not high when using LZO but I gues it > >>can vary > >>from platform to platform. > >>The size of the SPL binary is increased (1.5kB more code on ARM), but the > >>compression > >>really flattens the DTBS. so at the end of the day, enabling this option > >>doesn't add much. > >> > >>Here are some sumbers with a DRA7 platform (numbers in bytes): > >> size delta with ref > >> MLO.reference 123450 > >> MLO.lzo_1_DTB 123715 +265 > >> MLO.lzo_4_DTB 124237 +787 > >> MLO.gzip_4_DTB 132006 +8556 > >> MLO.no_comp_4_DTB 134184 +10734 > >Bearing in mind that you said in a follow up this is RFC, I'm ignoring > >all of the stuff that I believe you would fix in a v1. At the heart of > >it, are you able to tell different boards before you have a DTB loaded? > In my case (DRA7) the board can be identified before the dtb is > loaded. The identification > is done by reading an eeprom on I2c. It just can't be using DM I2C > in the SPL. > >I keep coming back to the problem that for SPL it seems like we should > >be able to do what Franklin did for keystone > >(https://patchwork.ozlabs.org/patch/777242/) and have a 'fake' dts file > >that represents the SoC such that any real boards can get U-Boot loaded > >and from there have the real board dtb be used. Or am I forgetting > >something? Thanks! > That's more or less the situation now with DRA7. This idea comes > from the need to accelerate the fastboot path by using the HS200 > mode of the eMMC. There we need to configure the lines of the eMMC > and this information is typically found in the DTB and differs from > SOC to SOC. At the moment in the ti tree this is done by duplicating > this information in C structures protected with #ifdef > CONFIG_SPL_BUILD. While this works, it would be nicer to get it from > the dtb as done in u-boot.
OK. Lets move forward with seeing what this looks like as a clean series of patches with everything new being opt-in, thanks! -- Tom
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