On Fri, 09 Jun 2023 22:26:21 +0200 Jernej Škrabec <jernej.skra...@gmail.com> wrote:
Hi, > Dne sreda, 07. junij 2023 ob 02:07:43 CEST je Andre Przywara napisal(a): > > Currently there is one DRAM parameter struct for the Allwinner H616 DRAM > > "driver". It contains many fields that are compile time constants > > (set by Kconfig variables), though there are also some fields that are > > probed and changed over the runtime of the DRAM initialisation. > > > > Because of this mixture, the compiler cannot properly optimise the code > > for size, as it does not consider constant propagation in its full > > potential. > > > > Help the compiler out by splitting that structure into two: one that only > > contains values known at compile time, and another one where the values > > will actually change. The former can then be declared "const", which will > > let the compiler fold its values directly into the code using it. > > > > We also add "const" tags for some new "struct dram_config" pointers, to > > further increase code optimisation. > > To help the compiler optimise the code further, the definition of the > > now "const struct dram_para" has to happen at a file-global level, so > > move that part out of sunxi_dram_init(). > > > > That results in quite some code savings (almost 2KB), and helps to keep > > the code small with the LPDDR3 support added later. > > > > Signed-off-by: Andre Przywara <andre.przyw...@arm.com> > > Nice trick. It could be used also in other DRAM drivers. You bet ;-) I have a patch for the H6 already. It doesn't save as much there (merely 500 bytes), I guess because we don't have as many build time parameters, but the H6 SPL is very big, so every byte saved there is a win. Will post this ASAP. > Reviewed-by: Jernej Skrabec <jernej.skra...@gmail.com> Many thanks for that! Cheers, Andre