From mboxrd@z Thu Jan 1 00:00:00 1970 From: Simon Goldschmidt Date: Mon, 14 Jan 2019 19:58:59 +0100 Subject: [U-Boot] [PATCH v1 1/4] arm: socfpga: imply SPL config instead of select In-Reply-To: <1c639b12-e963-f5b4-9136-83ebe0cd1a9b@denx.de> 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> Message-ID: <60997006-4808-2931-0612-5a32a0db601c@gmail.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de Am 14.01.2019 um 19:31 schrieb Marek Vasut: > 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 ? Ok, so that at leat shows me I'm going into the right direction :-) There are some problems though: - I do care (we're running 4.9 currently) *g* - people running an RT kernel will care for a while (until the next stable RT after fixing this will be released) - we would currently be breaking *all* kernels, since no kernel should yet be able to deassert reset for mmc and qspi (unless this is already done by U-Boot)... So would it be OK to add a Kconfig option to U-Boot to keep the current behaviour (for old broken kernels like you said) until that code is spread widely enough? Or is that a no-go? Regards, Simon