On Fri, 09 Jun 2023 22:26:21 +0200 Jernej Škrabec jernej.skrabec@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.przywara@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.skrabec@gmail.com
Many thanks for that!
Cheers, Andre