On Mon, 20 Mar 2023 08:59:59 +0800 John Sanpe sanpeqf@gmail.com wrote:
Hi John,
thanks for sending this, and sorry for the delay.
External use mhz to express frequency, autofresh use hz, no unit conversion is performed when calling, cause dram instability at low frequency.
What low frequency? Are you running it with less than 156 MHz?
Anyway I had a deeper look at this DRAM driver a while ago, and made some significant cleanups. One of them affects dram_set_autofresh_cycle(), which is ... weird ... to say at least. Not only does it support specifying the frequency both in MHz or Hz, it also uses some quite obfuscated arithmetic to avoid divisions. This is what I made of this function: https://github.com/apritzel/u-boot/commit/729d3c61b62
This is part of the whole cleanup series, which is not quite ready yet, but I put a WIP branch up anyway: https://github.com/apritzel/u-boot/commits/suniv-dram-WIP
As a bonus this allows to run the DRAM at 204 MHz, with JEDEC timings, which was not only quite stable for me (ran memtester over the weekend), but also provided quite some performance advantage.
It would be nice if you could give this series a go, and see if it works for you. Feel free to play around with the frequency, it should now program optimised timings for each rate.
Regarding your patch: I am afraid this is somewhat obsoleted by my series, also it seems to just paper over the actual problems, which probably are in the crude arithmetic.
Cheers, Andre
Incorporated xboot repair patch for this driver.
Signed-off-by: John Sanpe sanpeqf@gmail.com
arch/arm/mach-sunxi/dram_suniv.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/arm/mach-sunxi/dram_suniv.c b/arch/arm/mach-sunxi/dram_suniv.c index 3aa3ce7627..830fa7895d 100644 --- a/arch/arm/mach-sunxi/dram_suniv.c +++ b/arch/arm/mach-sunxi/dram_suniv.c @@ -310,7 +310,7 @@ static u32 dram_get_dram_size(struct dram_para *para) para->size = 64; else para->size = 32;
- dram_set_autofresh_cycle(para->clk);
- dram_set_autofresh_cycle(para->clk * 1000000); para->access_mode = 0; dram_para_setup(para);