On Fri, May 22, 2020 at 08:22:47AM -0700, Sowjanya Komatineni wrote: > > On 5/22/20 5:34 AM, Thierry Reding wrote: > > 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. > > Both of these quirks are different. > > PADCALIB is for auto calibration support. > > NEEDS_PAD_CONTROL is for SoC having separate 3V3 and 1V8 pads where they > have pad state selection and also diff drive strengths apply based on 3V3 > and 1V8 which are used only when auto cal is not used/failed. Great, would you mind sending out a patch that describes their uses somewhere above their definitions? It'd be good to have this documented in the code in case this ever comes up again. Thierry
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