From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marek Vasut Date: Mon, 14 Jan 2019 22:30:36 +0100 Subject: [U-Boot] [PATCH v1 1/4] arm: socfpga: imply SPL config instead of select In-Reply-To: <20190114212818.GR5463@bill-the-cat> References: <20190107211423.10151-1-simon.k.r.goldschmidt@gmail.com> <20190107211423.10151-2-simon.k.r.goldschmidt@gmail.com> <033b301a-612d-3b80-7ecc-04530851c1ec@denx.de> <1dd165cd-2cad-013b-877c-78fe5780f9cf@gmail.com> <00f186a1-7aea-8d46-770d-b5e08f1f92c2@denx.de> <8d7142cb-5674-57d2-dce2-a4595b8a5538@gmail.com> <9bcf5990-df16-b10f-4f61-4f40bdcd5eb0@kernel.org> <28940ce1-aba0-6fcc-7dcb-8d6f4bc34ea1@gmail.com> <1c639b12-e963-f5b4-9136-83ebe0cd1a9b@denx.de> <20190114212818.GR5463@bill-the-cat> Message-ID: <9e679556-3e5c-07bf-1473-68a1b0263f35@denx.de> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de On 1/14/19 10:28 PM, Tom Rini wrote: > On Mon, Jan 14, 2019 at 07:31:26PM +0100, Marek Vasut wrote: >> On 1/14/19 5:05 PM, Simon Goldschmidt wrote: >>> Hi Dinh, >> >> Hi, >> >>> 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. >> >> We had the same problem with A10, indeed. >> >>> 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... >> >> Yes, it'd break old broken kernels . The real question is, do we care ? > > Yes, we care. Especially since it sounds like we're talking about > something that's an LTS and not super-ancient vendor kernel. Off the > top of my head I can't recall if we ever fully removed support in sunxi > for the vendor kernel in some cases, or just made it, eventually, opt-in > as it was a fairly annoying incompatible behavior case. > > But yes, in general, we do care about old kernels and need to be loud > and clear about when we're removing support for them on a given SoC due > to it being a PITA to support both ways of doing X and people have had Y > years to migrate or correct their kernel. Then we have to add some fallback mechanism, possibly the env variable to tell reset controller to unreset everything. -- Best regards, Marek Vasut