Hi York,
-----Original Message----- From: York Sun [mailto:york.sun@nxp.com] Sent: Thursday, April 20, 2017 11:22 AM To: Peng Fan peng.fan@nxp.com; sbabic@denx.de; jh80.chung@samsung.com Cc: otavio@ossystems.com.br; u-boot@lists.denx.de Subject: Re: [PATCH 1/4] mmc: fsl_esdhc: introduce vs18_enable for 1.8V fix I/O
On 04/19/2017 07:46 PM, Peng Fan wrote:
When using eMMC with 1.8V I/O, the VSELECT bit need to be set in the USDHC controller when init.
This patch adds a parameter "vs18_enable" in fsl_esdhc_cfg structure and priv data, so each controller can have different settings.
We could not use CONFIG_SYS_FSL_ESDHC_FORCE_VSELECT, it has problem that it will apply to all USDHC controllers and it only set the 1.8V at init phase. So if user does not select to the eMMC device, the voltage on the I/O pins are not correct.
Peng,
I don't quite understand this. Isn't the voltage supplied by the board? I believe we have detection on our boards to decide 3.3v or 1.8v should be supplied. Does that have anything to do with the voltage you are talking about? I am referring to LS1046ARDB.
From i.MX6 RM, the VSELECT bit, Voltage Selection Change the value of output signal VSELECT, to control the voltage on pads for external card. There must be a control circuit out of uSDHC to change the voltage on pads. 1 Change the voltage to low voltage range, around 1.8 V 0 Change the voltage to high voltage range, around 3.0 V
If the emmc vqmmc supply is 1.8V, the vselect must be set to 1. I am not sure if this is the case for LS family.
Thanks, Peng.
York