On Thu, Jun 19, 2014 at 1:49 AM, Sachin Kamat <spk.linux@xxxxxxxxx> wrote: > +cc Some relevant guys from Samsung > > On Thu, Jun 19, 2014 at 2:12 PM, Tim Kryger <tim.kryger@xxxxxxxxx> wrote: >> On Wed, Jun 18, 2014 at 8:54 PM, Sachin Kamat <spk.linux@xxxxxxxxx> wrote: >> >>>> On Wed, Jun 18, 2014 at 4:33 AM, Sachin Kamat <spk.linux@xxxxxxxxx> wrote: >> >>>>> I see the below error on Exynos4210 based Origen board with linux-next >>>>> (20140618). >>>>> Reverting the below commit works fine. >>>>> >>>>> Commit: 8d02e775a6 "mmc: sdhci: Use mmc core regulator infrastucture" >> >>>>> >>>>> -- [ 2.068992] sdhci: Secure Digital Host Controller Interface driver >>>>> [ 2.075059] sdhci: Copyright(c) Pierre Ossman >>>>> [ 2.079762] of_get_named_gpiod_flags: can't parse gpios property of >>>>> node '/sdhci@12510000[0]' >>>>> [ 2.088021] s3c-sdhci 12510000.sdhci: clock source 2: mmc_busclk.2 >>>>> (50000000 Hz) >>>>> [ 2.095322] of_get_named_gpiod_flags: can't parse gpios property of >>>>> node '/sdhci@12510000[0]' >>>>> [ 2.103794] of_get_named_gpiod_flags: can't parse gpios property of >>>>> node '/sdhci@12510000[0]' >>>>> [ 2.112478] s3c-sdhci 12510000.sdhci: No vqmmc regulator found >>>>> [ 2.118117] mmc0: Hardware doesn't report any support voltages. >>>>> [ 2.124004] s3c-sdhci 12510000.sdhci: sdhci_add_host() failed >>>>> [ 2.130080] of_get_named_gpiod_flags: can't parse gpios property of >>>>> node '/sdhci@12530000[0]' >>>>> [ 2.138352] s3c-sdhci 12530000.sdhci: clock source 2: mmc_busclk.2 >>>>> (16666667 Hz) >>>>> [ 2.145661] of_get_named_gpiod_flags: can't parse gpios property of >>>>> node '/sdhci@12530000[0]' >>>>> [ 2.154139] of_get_named_gpiod_flags: can't parse gpios property of >>>>> node '/sdhci@12530000[0]' >>>>> [ 2.162834] s3c-sdhci 12530000.sdhci: No vqmmc regulator found >>>>> [ 2.168464] mmc0: Hardware doesn't report any support voltages. >>>>> [ 2.174349] s3c-sdhci 12530000.sdhci: sdhci_add_host() failed >> >>>>> [ 2.336148] Waiting for root device /dev/mmcblk0p1... >> >>> FYI, the board has a 2.8V fixed regulator supply connected to the MMC. >>> You may refer to arch/arm/boot/dts/exynos4210-origen.dts for more details. >> >> A 2.8v regulator results in mmc->ocr_avail being set to MMC_VDD_27_28 >> | MMC_VDD_28_29. >> >> The SDHCI capabilities register only indicates support of three voltage levels >> - 1.8v: SDHCI_CAN_VDD_180 => MMC_VDD_165_195 >> - 3.0v: SDHCI_CAN_VDD_300 => MMC_VDD_29_30 | MMC_VDD_30_31 >> - 3.3v: SDHCI_CAN_VDD_330 => MMC_VDD_32_33 | MMC_VDD_33_34 >> >> Even if all capability bits of the host controller were set, there >> still wouldn't be any overlap. Thus you see a "Hardware doesn't >> report any support voltages" message. >> >> Previously, this issue was being swept under the rug by cec2e21 mmc: >> sdhci: Use regulator min/max voltage range according to spec. That >> change hacked up the voltage range checks such that with your 2.8v >> fixed regulator, the driver would believe the host could support >> MMC_VDD_29_30 | MMC_VDD_30_31 | MMC_VDD_32_33 | MMC_VDD_33_34. The >> driver would start down the path of commanding 3.3v-3.4v (the highest >> voltage range believed to be supported). At the last second, the >> driver would see the regulator was fixed and blindly skip over the set >> voltage operation, saving it from failure. >> >> Since my patch eliminates the bogus voltage range checks, your board >> is now getting caught playing too loose with the SDHCI regulator >> voltages. >> >> Furthermore, the fixed regulator special-case logic that helped hide >> your issue should also be considered for removal given that fixed >> regulators now behave properly thanks to c00dc35 regulator: core: >> Allow regulator_set_voltage for fixed regulators. > > Thanks for the detailed explanation. What do you propose to get this fixed? I'm not really sure of the best path forward. I suppose you could modify your device tree to lie about the voltage of the fixed regulator. Changing it to 3.0v should allow it to boot up but that is definitely a hack. It would be nice if the driver could be extended to handle the peculiarities of your board in a deliberate manner but limiting the common sdhci driver to supporting only the three voltages from the spec also seems sensible. -Tim -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
