From: Fabio Estevam <festevam@gmail.com>
To: Ulf Hansson <ulf.hansson@linaro.org>
Cc: Dong Aisheng <aisheng.dong@freescale.com>,
Kevin Lemoi <kevin.lemoi@savant.com>,
Otavio Salvador <otavio@ossystems.com.br>,
Sascha Hauer <kernel@pengutronix.de>,
Russell King - ARM Linux <linux@arm.linux.org.uk>,
"Dong, Chuanxiao" <chuanxiao.dong@intel.com>,
linux-mmc <linux-mmc@vger.kernel.org>,
Fabio Estevam <fabio.estevam@freescale.com>
Subject: Re: [PATCH v2] mmc: core: Do not set mmc voltage to 1.8V when 'no-1-8-v' is present
Date: Mon, 15 Jun 2015 09:23:01 -0300 [thread overview]
Message-ID: <CAOMZO5CSvYHNwmeRsSJ+KYfAkisX+_2DePawd6AWHP-ANErq5Q@mail.gmail.com> (raw)
In-Reply-To: <CAPDyKFq29S3K0sxCkUHO=QO0MqM0PskcjoM62EZysNc19SxP6w@mail.gmail.com>
Hi Ulf,
On Mon, Jun 15, 2015 at 9:08 AM, Ulf Hansson <ulf.hansson@linaro.org> wrote:
> What card (eMMC, SD, MMC) and which host driver is being used here?
It is an eMMC and the host driver is sdhci-esdhc-imx.c.
>> --- a/drivers/mmc/core/host.c
>> +++ b/drivers/mmc/core/host.c
>> @@ -527,6 +527,8 @@ int mmc_of_parse(struct mmc_host *host)
>> host->caps2 |= MMC_CAP2_HS400_1_8V | MMC_CAP2_HS200_1_8V_SDR;
>> if (of_find_property(np, "mmc-hs400-1_2v", &len))
>> host->caps2 |= MMC_CAP2_HS400_1_2V | MMC_CAP2_HS200_1_2V_SDR;
>> + if (of_find_property(np, "no-1-8-v", &len))
>> + host->caps2 |= MMC_CAP_3_3V_ONLY_DDR;
>
> Do you intend to use 3.3V as the I/O voltage level for an eMMCs
> running in DDR mode? Isn't that violation of the eMMC spec?
Yes, I would like to use 3.3V as the I/O voltage level for an eMMC in DDR mode.
This was the behaviour prior to 312449efd16bb0, which I would like to
keep so that our custom board based on mx6sl could work. It works fine
with 3.14 kernel, but not on 4.1-rc due to the fact that the board
cannot provide 1.8V level, hence 'no-1-8-v' property is passed in the
device tree. With this patch applied 3.3V is applied and the eMMC can
successfully operate in 3.3V DDR mode.
Regards,
Fabio Estevam
next prev parent reply other threads:[~2015-06-15 12:23 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-13 20:24 [PATCH v2] mmc: core: Do not set mmc voltage to 1.8V when 'no-1-8-v' is present Fabio Estevam
2015-06-15 11:44 ` Otavio Salvador
2015-06-15 12:08 ` Ulf Hansson
2015-06-15 12:23 ` Fabio Estevam [this message]
2015-06-15 12:49 ` Fabio Estevam
2015-06-16 9:31 ` Ulf Hansson
2015-06-17 16:25 ` Fabio Estevam
2015-06-18 7:58 ` Ulf Hansson
2015-06-18 14:25 ` Dong Aisheng
2015-06-18 14:03 ` Dong Aisheng
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