Hi Dinh,
Am 14.01.2019 um 16:58 schrieb Dinh Nguyen:
Hi Simon,
On 1/14/19 9:50 AM, Simon Goldschmidt wrote:
Am 11.01.2019 um 23:02 schrieb Marek Vasut:
On 1/11/19 9:39 PM, Simon Goldschmidt wrote:
Am 07.01.2019 um 23:53 schrieb Marek Vasut:
On 1/7/19 10:14 PM, Simon Goldschmidt wrote:
In order to build a smaller SPL, let's imply SPL_DM_RESET and
SPL_WATCHDOG_SUPPORT instead of selecting them, so they can be
disabled
via defconfig.
This also seems to be required to use OF_PLATDATA, as the reset
drivers
don't seem to work with it.
How do you un-reset IP blocks if you disable the reset controller ?
I found that out just now: there's the function
'reset_deassert_peripherals_handoff()' in spl_gen5.c that should
"De-assert reset for peripherals and bridges based on handoff". However,
at least for Gen5, it just writes a 0 to rstmgr->permodrst. By doing
that, it enables *ALL* peripherals on the SoC (except for some DMA
channels that aren't really used) :-)
I guess that needs some cleaning up as well ;-)
Yes
I think the proper thing to do here would be to remove this function and
convert all drivers to provide appropriate 'resets' properties in the
dts?
Indeed
So I just did that and it works nice for SPL and U-Boot: By adding some
"resets" properties the the main dtsi and adding reset bulk code to the
cadence_qspi, denali_dt nand and drivers, I can nearly remove the reset
code from arch/mach_socfpga.
The problem would be that now Linux cannot use peripherals that aren't
enabled by U-Boot because it relies on them being enabled. How are such
dependencies solved? Because even if I would add reset support in the
corresponding Linux drivers, we probably could not bootolder Kernels
(e.g. the Debian 9 kernel - v4.9.x) with a new U-Boot...
I added an early reset driver for SoCFPGA that should take care of this.
The patch is in v5.0-rc2[1].
OK, it's good to know that this work is already done, I haven't
monitored this close enough.
But am I correct that my above problem remains even in v5.0 as not all
peripherals in socfpga.dtsi have a "resets" property set (e.g. mmc and
qspi) and would thuse not be taken out of reset by Linux?
Plus: should U-Boot work with older Linux kernels? Because if so, we
need fallback code in U-Boot to unreset peripherals when running with an
older kernel...
Regards,
Simon
Dinh
[1]
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/drivers/reset?id=b3ca9888f35fa6919569cf27c929dc0ac49e9716
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