Hi Tony,
On 2/27/23 01:11, Tony Dinh wrote:
Hi Pali,
On Sun, Feb 26, 2023 at 2:52 AM Pali Rohár <p...@kernel.org> wrote:
On Saturday 25 February 2023 20:56:10 Tony Dinh wrote:
Hi Martin,
On Sat, Feb 25, 2023 at 6:17 PM Martin Rowe <martin.p.r...@gmail.com> wrote:
I'm not sure how to run proper timing tests on the process, but
stopwatch timing just between seeing "Trying to boot" and "U-Boot
2023.04-rc2" showed the return to BootROM under 1 second, and the
direct from SPI around 4 seconds. I thought the goal of loading from
SPI directly was speed, but returning to BootROM is significantly
faster on this board.
You should check SPI speed in DTS file and also in the defconfig.
I think we have probably seen this slowdown before. There is a TODO in
the way the DTS nodes are parsed by DM uclass. So this config must be
set in defconfig to get around that bug:
CONFIG_SF_DEFAULT_SPEED=50000000
That works and is much faster now. I'll submit it in a V2 for these
two patches once Pali's mvebu changes are accepted. Only question I
have is: should the faster speed be applied to all three defconfigs?
CONFIG_SF_DEFAULT_SPEED=1000000 (50x less) is implicitly added to the
MMC and SATA configs at the moment.
This is only a workaround to get the SPI probe to work correctly. The
real fix should be in spi_flash_probe()
./common/spl/spl_spi.c
flash = spi_flash_probe(sf_bus, sf_cs,
CONFIG_SF_DEFAULT_SPEED,
CONFIG_SF_DEFAULT_MODE);
If spi_flash_probe() failed to get SPI max_hz from the DTS, the
fallback is CONFIG_SF_DEFAULT_SPEED.
IMO, perhaps we could add CONFIG_SF_DEFAULT_SPEED and
CONFIG_SF_DEFAULT_MODE selection to arch/arm/mach-mvebu/Kconfig or
some other common place. And when we will have fixed the DTS parsing
problem, they can be removed.
I'd like to hear from Stefan and Pali if this approach sounds good.
All the best,
Tony
Well, the maximal SPI speed depends on the wiring. You can have on the
board some SPI device which does not support high frequency.
But having some sane defaults in Kconfig for mvebu makes sense.
Agreed.
The CONFIG_SF_DEFAULT_SPEED is set to 1_000_000 if the board defconfig
does not specify it. I think the sane default value is 10_000_000
(grepping the Armada* DTS files showing the slowest spi-max-frequency
is 10_000_000). While a big improvement, it is not fast enough for
many other boards. So we still need to define it in those board
defconfigs (before fixing that bug), or use return to BootROM.
I'm fine with setting CONFIG_SF_DEFAULT_SPEED to 10.000.000 for MVEBU.
Not sure if this should be done in drivers/mtd/spi/Kconfig, as this
currently has no platform- / board- specific configurations. Perhaps
it can be done in a mach-mvebu Kconfig file instead?
Thanks,
Stefan
