On Fri, May 22, 2020 at 03:18:40PM +0300, Dmitry Osipenko wrote: > 22.05.2020 15:13, Thierry Reding пишет: > > On Wed, May 20, 2020 at 09:09:33AM -0700, Sowjanya Komatineni wrote: > >> > >> On 5/20/20 4:26 AM, Ulf Hansson wrote: > >>> On Wed, 20 May 2020 at 04:00, Dmitry Osipenko <digetx@xxxxxxxxx> wrote: > >>>> 19.05.2020 23:44, Sowjanya Komatineni пишет: > >>>>> On 5/19/20 12:07 PM, Sowjanya Komatineni wrote: > >>>>>> On 5/19/20 11:41 AM, Sowjanya Komatineni wrote: > >>>>>>> On 5/19/20 11:34 AM, Sowjanya Komatineni wrote: > >>>>>>>> On 5/19/20 9:33 AM, Dmitry Osipenko wrote: > >>>>>>>>> 19.05.2020 19:24, Thierry Reding пишет: > >>>>>>>>>> On Tue, May 19, 2020 at 05:05:27PM +0300, Dmitry Osipenko wrote: > >>>>>>>>>>> 19.05.2020 10:28, Ulf Hansson пишет: > >>>>>>>>>>>> On Sat, 16 May 2020 at 17:44, Dmitry Osipenko <digetx@xxxxxxxxx> > >>>>>>>>>>>> wrote: > >>>>>>>>>>>>> Several people asked me about the MMC warnings in the KMSG log and > >>>>>>>>>>>>> I had to tell to ignore them because these warning are > >>>>>>>>>>>>> irrelevant to > >>>>>>>>>>>>> pre-Tegra210 SoCs. > >>>>>>>>>>>> Why are the warnings irrelevant? > >>>>>>>>>>> That's what the DT binding doc says [1]. > >>>>>>>>>>> > >>>>>>>>>>> [1] > >>>>>>>>>>> https://www.kernel.org/doc/Documentation/devicetree/bindings/mmc/nvidia%2Ctegra20-sdhci.txt > >>>>>>>>>>> > >>>>>>>>>>> > >>>>>>>>>>> Although, looking at the driver's code and TRM docs, it seems > >>>>>>>>>>> that all > >>>>>>>>>>> those properties are really irrelevant only to the older Terga20 > >>>>>>>>>>> SoC. So > >>>>>>>>>>> the binding doc is a bit misleading. > >>>>>>>>>>> > >>>>>>>>>>> Nevertheless, the binding explicitly says that the properties are > >>>>>>>>>>> optional, which is correct. > >>>>>>>>>> Optional only means that drivers must not fail if these properties > >>>>>>>>>> aren't found, it doesn't mean that the driver can't warn that they > >>>>>>>>>> are missing. > >>>>>>>>>> > >>>>>>>>>> Quite possibly the only reason why they were made optional is because > >>>>>>>>>> they weren't part of the bindings since the beginning. Anything added > >>>>>>>>>> to a binding after the first public release has to be optional by > >>>>>>>>>> definition, otherwise DT ABI wouldn't be stable. > >>>>>>>>>> > >>>>>>>>>> I think these warnings were added on purpose, though I also see that > >>>>>>>>>> there are only values for these in device tree for Tegra186 and > >>>>>>>>>> Tegra194 > >>>>>>>>>> but not Tegra210 where these should also be necessary. > >>>>>>>> dt binding doc we have is common for MMC, SD and SDIO of all Tegras. > >>>>>>>> Its not mandatory to have both 3v3 and 1v8 in device tree as based > >>>>>>>> on signal mode. > >>>>>>>> > >>>>>>>> As these driver strengths are SoC specific, they are part of Tegra > >>>>>>>> SoC specific device tree where same values will be applicable to all > >>>>>>>> Tegra SoC specific platforms. > >>>>>>>> > >>>>>>>> Based on interface usage on platform, we use one or both of them > >>>>>>>> like sdcard supports dual voltage and we use both 3V3 and 1V8 but if > >>>>>>>> same interface is used for WIFI SD we use 1V8 only. > >>>>>>>> > >>>>>>>> So made these dt properties as optional. > >>>>>>>> > >>>>>>>> Other reason they are optional is, Tegra210 and prior has drive > >>>>>>>> strength settings part of apb_misc and Tegra186 and later has driver > >>>>>>>> strengths part of SDMMC controller. So, > >>>>>>>> > >>>>>>>> - Pinctrls "sdmmc-3v3-drv" and "sdmmc-1v8-drv" for driver strengths > >>>>>>>> are applicable for Tegra210 and prior. > >>>>>>>> - dt properties pad-autocal-pull-up/down-offset-1v8/3v3-timeout are > >>>>>>>> for T186 onwards for driver strengths > >>>>>>>> > >>>>>>>> Looks like dt binding doc need fix to clearly document these based > >>>>>>>> on SoC or agree with Yaml we can conditionally specify pinctrl or dt > >>>>>>>> properties based on SoC dependent. > >>>>>>>> > >>>>>>>> > >>>>>>>>>> Adding Sowjanya who wrote this code. Perhaps she can clarify why the > >>>>>>>>>> warnings were added. If these values /should/ be there on a subset of > >>>>>>>>>> Tegra, then I think we should keep them, or add them again, but > >>>>>>>>>> perhaps > >>>>>>>>>> add a better way of identifying when they are necessary and when > >>>>>>>>>> it is > >>>>>>>>>> safe to work without them. > >>>>>>>>>> > >>>>>>>>>> That said, looking at those checks I wonder if they are perhaps just > >>>>>>>>>> wrong. Or at the very least they seem redundant. It looks to me like > >>>>>>>>>> they can just be: > >>>>>>>>>> > >>>>>>>>>> if (tegra_host->pinctrl_state_XYZ == NULL) { > >>>>>>>>>> ... > >>>>>>>>>> } > >>>>>>>>>> > >>>>>>>>>> That !IS_ERR(...) doesn't seem to do anything. But in that case, it's > >>>>>>>>>> also obvious why we're warning about them on platforms where these > >>>>>>>>>> properties don't exist in DT. > >>>>>>>> As drive strengths are through dt properties for T186 and later and > >>>>>>>> thru pinctrl for T210 and prior, driver first checks for dt autocal > >>>>>>>> timeout pull-up/down properties and if they are not found, it then > >>>>>>>> checks for presence of pinctrl_state_xyx_drv only when valid > >>>>>>>> pinctrl_state_xyz is present. > >>>>>>>> > >>>>>>>> Driver expects either pinctrl or dt properties and shows warning > >>>>>>>> when neither of them are present as its mandatory to use fixed > >>>>>>>> driver strengths when auto calibration fails. > >>>>>>>> > >>>>>>>> err = device_property_read_u32(host->mmc->parent, > >>>>>>>> "nvidia,pad-autocal-pull-down-offset-3v3-timeout", > >>>>>>>> &autocal->pull_down_3v3_timeout); > >>>>>>>> if (err) { > >>>>>>>> if (!IS_ERR(tegra_host->pinctrl_state_3v3) && > >>>>>>>> (tegra_host->pinctrl_state_3v3_drv == NULL)) > >>>>>>>> pr_warn("%s: Missing autocal timeout 3v3-pad drvs\n", > >>>>>>>> mmc_hostname(host->mmc)); > >>>>>>>> autocal->pull_down_3v3_timeout = 0; > >>>>>>>> } > >>>>>>>> > >>>>>>>>>> So I think we either need to add those values where appropriate so > >>>>>>>>>> that > >>>>>>>>>> the warning doesn't show, or we need to narrow down where they are > >>>>>>>>>> really needed and add a corresponding condition. > >>>>>>>>>> > >>>>>>>>>> But again, perhaps Sowjanya can help clarify if these really are only > >>>>>>>>>> needed on Tegra210 and later or if these also apply to older chips. > >>>>>>>>> Either way will be cleaner to convert the DT binding to YAML rather > >>>>>>>>> than > >>>>>>>>> clutter the driver, IMO. > >>>>>>>>> > >>>>>>>> > >>>>>>>> > >>>>>>> Auto calibration is present from Tegra30 onward and looking into > >>>>>>> change where autocalibration was added to sdhci driver somehow it was > >>>>>>> enabled only for T30/T210/T186/T194. > >>>>>>> > >>>>>>> tegra_sdhci_parse_pad_autocal_dt() was added when auto-calibration > >>>>>>> was added to driver and I see this dt parse is being done > >>>>>>> irrespective of NVQUIRK_HAS_PADCALIB quirk so even on platforms > >>>>>>> without auto cal enabled in driver, these messages shows up. > >>>>>>> > >>>>>>> This should be fixed in driver to allow > >>>>>>> tegra_sdhci_parse_pad_autocal_dt() only when NVQUIRK_HAS_PADCALIB is > >>>>>>> set to avoid dt parsing to happen on platforms that don't have auto > >>>>>>> cal enabled. > >>>>>> Warning on missing drive strengths when auto cal is enabled should be > >>>>>> present as we should switch to fixed recommended drive strengths when > >>>>>> auto cal fails. > >>>>>> > >>>>>> So probably proper fix should be > >>>>>> > >>>>>> - allow tegra_sdhci_parse_pad_autocal_dt() only when > >>>>>> NVQUIRK_HAS_PADCALIB is set > >>>>>> > >>>>>> - current driver sets NVQUIRK_HAS_PADCALIB for T30 as well so need to > >>>>>> add pinctrls "sdmmc-3v3-drv" and "sdmmc-1v8-drv" to Tegra30 device tree. > >>>>> [Correction] T30 has same drive strengths to use irrespective of signal > >>>>> voltage and it doesn't have pad control. So for T3- we can update device > >>>>> tree to specify "default" pinctrl with drvup/dn settings. > >>>>>> - Keep warning message of missing auto cal timeouts as its mandatory > >>>>>> to use fixed recommended driver strengths when auto cal fails. > >>>>>> > >>>>> Regarding warnings, I guess simpler and easy fix is to remove warning > >>>>> message on missing 3v3/1v8 drive strengths as pinctrl/dt properties were > >>>>> already added for T210/186/194 where we need and old device tree don't > >>>>> have them but the case where auto cal can fail is very rare. > >>>>> > >>>>> Otherwise should update driver to allow > >>>>> tegra_sdhci_parse_pad_autocal_dt() only when NVQUIRK_HAS_PADCALIB is set > >>>>> and also within tegra_sdhci_parse_pad_autocal_dt() show warning of > >>>>> missing 3v3/1v8 settings only when NVQUIRK_NEEDS_PAD_CONTROL is set. > >>>>> > >>>>> Thierry, please suggest if you prefer to removing warnings or fix driver > >>>>> to show warning based on PADCALIB and PAD_CONTROL quirks. > >>>> The SDIO PINCTRL drive-strengths are usually a part of the board's > >>>> default PINCTRL state, which is either preset by bootloader or by > >>>> PINCTRL driver early at a boot time. > >>>> > >>>> The SDIO drive-strengths values should be board-specific and not > >>>> SoC-specific because they should depend on the electrical properties of > >>>> the board, IIUC. > >> > >> Drive strengths we program here when auto calibration fails are recommended > >> values based on pre-SI circuit analysis and characterized across PVT. > >> > >> So, these fail safe values are same for all boards of specific SoC as all > >> platform designs follow the design guidelines. > >> > >>>> If the SDIO PINCTRL states are mandatory for the SDHCI nodes in the > >>>> device-trees, then the DT binding is wrong since it says that all > >>>> properties are optional. But I think that the current binding is okay, > >>>> since today SDHCI PINCTRL drive-strengths are specified implicitly in > >>>> the device-trees, and thus, there is no real need to emit the noisy > >>>> warnings in this case. > >>> For now I will keep $subject patch applied, but please tell me if I > >>> should drop it so we can start over. > >>> > >>> In any case, I would appreciate it if someone could have a stab at > >>> converting sdhci and tegra DT bindings to yaml. > >>> > >>> Kind regards > >>> Uffe > >> > >> HI Uffe, > >> > >> Please drop $subject patch. Will send patch that allows parsing for these > >> properties only for SoC where auto cal is enabled as that's where driver > >> needs these properties. > >> > >> So with this fix, warning will not show up on systems where autocal is not > >> enabled. > > > > Yes, I think that's a better option. Have we ensured that on all systems > > where autocal is enabled these values are part of the device tree? Just > > making sure that we're not going to have some generation still spit out > > these warnings because we forgot to update the device tree. > > > > For example I see that we set NVQUIRK_HAS_PADCALIB but I don't see these > > properties being set in arch/arm/boot/dts/tegra30.dtsi. Can you add a > > patch that also adds the properties for Tegra30? > > I don't see the warnings on T30 using Sowjanya's patch which checks for > NVQUIRK_NEEDS_PAD_CONTROL and not NVQUIRK_HAS_PADCALIB. Yeah, I noticed that too when looking at Sowjanya's patch. The fact that we have two of these quirks is somewhat confusing to me. Perhaps we can add a comment near their definition to clarify what their purpose is? Thierry
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