From mboxrd@z Thu Jan 1 00:00:00 1970 From: Adrian Hunter Subject: Re: [RFC] mmc: core: add the capability for broken voltage Date: Tue, 17 Jan 2012 11:37:32 +0200 Message-ID: <4F15415C.6020205@intel.com> References: <4F13E47D.8040505@samsung.com> <4F152A8F.5070506@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from mga14.intel.com ([143.182.124.37]:9581 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752400Ab2AQJhc (ORCPT ); Tue, 17 Jan 2012 04:37:32 -0500 In-Reply-To: Sender: linux-mmc-owner@vger.kernel.org List-Id: linux-mmc@vger.kernel.org To: Kyungmin Park Cc: Jaehoon Chung , linux-mmc , Chris Ball , Mark Brown On 17/01/12 11:05, Kyungmin Park wrote: > On 1/17/12, Adrian Hunter wrote: >> On 16/01/12 10:49, Jaehoon Chung wrote: >>> This patch is added the MMC_CAP2_BROKEN_VOLTAGE. >>> >>> if the voltage didn't satisfy between min_uV and max_uV, >> >> Why is the fixed voltage not in the acceptable range for the card? >> Doesn't that risk breaking the card? > Hi Adrian, > > I don't know, they uses the not supported voltage. but it's worked > properly for long time. I wonder if there is a generic problem here that this fix hides. It would be nice to have an explanation. Do you know: - what is the fixed voltage? - is it supplying VCC or VCCQ? - what is the contents of the OCR register? > Galaxy S2 also uses the same voltage as ours. > > I also think the modify the regulator framework to support voltage > change at fixed regulator. but it's not good idea and doesn't match > the regulator concept. so modify the sdhci codes to support our > boards. > > Thank you, > Kyungmin Park >> >>> try to change the voltage in core.c. >>> When change the voltage, maybe use the regulator_set_voltage(). >>> >>> In regulator_set_voltage(), check the below condition. >>> >>> /* sanity check */ >>> if (!rdev->desc->ops->set_voltage && >>> !rdev->desc->ops->set_voltage_sel) { >>> ret = -EINVAL; >>> goto out; >>> } >>> >>> If Some-board should use the fixed-regulator, always return -EINVAL. >>> Then, eMMC didn't initialize always. >>> >>> So if use the fixed-regulator or etc, we need to add the >>> MMC_CAP2_BROKEN_VOLTAGE. >>> >>> Signed-off-by: Jaehoon Chung >>> Signed-off-by: Kyungmin Park >>> --- >>> drivers/mmc/core/core.c | 4 ++++ >>> include/linux/mmc/host.h | 1 + >>> 2 files changed, 5 insertions(+), 0 deletions(-) >>> >>> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c >>> index bec0bf2..6848789 100644 >>> --- a/drivers/mmc/core/core.c >>> +++ b/drivers/mmc/core/core.c >>> @@ -1121,6 +1121,10 @@ int mmc_regulator_set_ocr(struct mmc_host *mmc, >>> * might not allow this operation >>> */ >>> voltage = regulator_get_voltage(supply); >>> + >>> + if (mmc->caps2 & MMC_CAP2_BROKEN_VOLTAGE) >>> + min_uV = max_uV = voltage; >>> + >>> if (voltage < 0) >>> result = voltage; >>> else if (voltage < min_uV || voltage > max_uV) >>> diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h >>> index dd13e05..5659aee 100644 >>> --- a/include/linux/mmc/host.h >>> +++ b/include/linux/mmc/host.h >>> @@ -257,6 +257,7 @@ struct mmc_host { >>> #define MMC_CAP2_HS200_1_2V_SDR (1 << 6) /* can support */ >>> #define MMC_CAP2_HS200 (MMC_CAP2_HS200_1_8V_SDR | \ >>> MMC_CAP2_HS200_1_2V_SDR) >>> +#define MMC_CAP2_BROKEN_VOLTAGE (1 << 7) /* Use the broken voltage */ >>> >>> mmc_pm_flag_t pm_caps; /* supported pm features */ >>> unsigned int power_notify_type; >>> -- >>> To unsubscribe from this list: send the line "unsubscribe linux-mmc" in >>> the body of a message to majordomo@vger.kernel.org >>> More majordomo info at http://vger.kernel.org/majordomo-info.html >> >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-mmc" in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html >> >