Re: Help with u-boot when using the eMMC card in DDR mode

[Abder <koute102030@gmail.com>]

The previously mentioned commit didn't resolve the issue. When testing I
made a mistake.

The workaround I'm using to resolve the issue is by disabling the DDR mode
juste before re-init happens (DDR mode will be automatically enabled later
in the init process).

Now I don't know if this is really a bug in the mmc driver, or I'm just
missing some additional configuration to work with the eMMC in DDR mode !




Le mar. 27 juil. 2021 à 15:14, Abder <koute102030@gmail.com> a écrit :

> Hi Jaehoon,
> yes, DDR mode works fine before executing "mmc dev 2" command.
> However, for "mmc rescan" command or "mmc info" to work, I need to first
> select the correct mmc device using the "mmc dev 2" command, cuz the
> default one is device 0 in my case which is empty.
>
> OTOH, after hours of debugging I found the origin of the issue. In fact,
> the "mmc dev 2" command forces a reinitialization of the emmc, and if the
> emmc was already initialized in DDR mode at boot up, the implemented
> re-init flow leads to bad clock settings.
> (basicly the host tries to set the clock of the emmc to 400KHz
> (identification mode), but as the DDR mode is still enabled, the
> configured clock corresponds to the half of that = 200KHz). The mismatch in
> frequency is what caused the -70 ECOM error.
> and as the command fails, the emmc stays at 200KHz, which leads any
> attempt to interact with the emmc afterwards to failure.
>
> I found out that this bug was patched recently in
> 390f9bddb9c84f75649024b41b8cf2a766379ce0 in the main u-boot.
>
> Anyhow.. Thanks for your replies.
>
> Best regards,
> Abder
>
>
> Le mar. 27 juil. 2021 à 04:03, Jaehoon Chung <jh80.chung@samsung.com> a
> écrit :
>
>> On 7/26/21 5:36 PM, Abder wrote:
>> > Hi Jaehoon,
>> > This is the output with MMC_TRACE enabled
>> >
>> > U-Boot >mmc dev 2
>> > blk_find_device: if_type=6, devnum=2: usdhc@02198000.blk, 6, 2
>> > ofnode_read_u32: vmmc-supply: 0x33 (51)
>> > ofnode_read_u32: vqmmc-supply: 0x33 (51)
>> > clock is disabled (0Hz)
>> > fixed_regulator_set_enable: dev='3p3v', enable=1, delay=0, has_gpio=0
>> > clock is enabled (400000Hz)
>> > CMD_SEND:0
>> >                 ARG                      0x00000000
>> >                 MMC_RSP_NONE
>> > CMD_SEND:8
>> >                 ARG                      0x000001aa
>> >                 RET                      -110
>> > CMD_SEND:55
>> >                 ARG                      0x00000000
>> >                 RET                      -110
>> > CMD_SEND:0
>> >                 ARG                      0x00000000
>> >                 MMC_RSP_NONE
>> > CMD_SEND:1
>> >                 ARG                      0x00000000
>> >                 MMC_RSP_R3,4             0x00ff8080
>> > CMD_SEND:1
>> >                 ARG                      0x40300000
>> >                 MMC_RSP_R3,4             0x00ff8080
>> > CMD_SEND:0
>> >                 ARG                      0x00000000
>> >                 MMC_RSP_NONE
>> > CMD_SEND:1
>> >                 ARG                      0x40300000
>> >                 MMC_RSP_R3,4             0x00ff8080
>> > CMD_SEND:1
>> >                 ARG                      0x40300000
>> >                 MMC_RSP_R3,4             0x00ff8080
>> > CMD_SEND:1
>> >                 ARG                      0x40300000
>> >                 MMC_RSP_R3,4             0x00ff8080
>> > CMD_SEND:1
>> >                 ARG                      0x40300000
>> >                 MMC_RSP_R3,4             0xc0ff8080
>> > CMD_SEND:2
>> >                 ARG                      0x00000000
>> >                 RET                      -70
>> > CMD_SEND:2
>> >                 ARG                      0x00000000
>> >                 RET                      -70
>> > CMD_SEND:2
>> >                 ARG                      0x00000000
>> >                 RET                      -70
>> > CMD_SEND:2
>> >                 ARG                      0x00000000
>> >                 RET                      -70
>> > CMD_SEND:2
>> >                 ARG                      0x00000000
>> >                 RET                      -70
>> > CMD_SEND:2
>> >                 ARG                      0x00000000
>> >                 RET                      -70
>> > Command failed, result=1
>> > U-Boot >
>> >
>> > I believe the -70 error is an ECOM error  (Communication error on send).
>> > However this does not occur when eMMC is in HS mode for example.
>> > and even in DDR mode, before executing the "mmc dev 2" cmd, the
>> > communication with the emmc with "load" works without a hitch.
>>
>> Sorry. I didn't understand clearly.
>> Does DDR mode work fine before "mmc dev 2" command?
>> Did you try to run other command? e,g) mmcinfo or mmc rescan?
>>
>> It seems that error is returned in fsl_esdhc_imx.c.
>> Well, it seems that not cleared something after some operation.
>> It needs to check full log and sequence.
>>
>> Best Regards,
>> Jaehoon Chung
>>
>> >
>> >
>> >
>> > Le lun. 26 juil. 2021 à 10:03, Jaehoon Chung <jh80.chung@samsung.com> a
>> > écrit :
>> >
>> >> Hi,
>> >>
>> >> On 7/26/21 4:41 PM, Abder wrote:
>> >>> Hi,
>> >>>
>> >>> I have been trying recently to optimize the boot time on a customized
>> >> board
>> >>> based on the IMX6DP.
>> >>>
>> >>> For the time being, I succeeded in enabling the DDR (dual data rate)
>> mode
>> >>> for the emmc to speed up the data rate for read and write cycles in
>> >> u-boot.
>> >>>
>> >>> By reading a file from the emmc using the "load" command (e.g. load
>> mmc
>> >> 2:1
>> >>> 0x12000000 file), I can see that the data rate has doubled, confirming
>> >> that
>> >>> the DDR mode is enabled.
>> >>>
>> >>> However, the problem I have is that when I execute the u-boot command
>> >> "mmc
>> >>> dev 2" to switch the current device to the onboard eMMC, the command
>> >> fails
>> >>> with the output below : (with DEBUG enabled)
>> >>
>> >> If you can enable CONFIG_MMC_TRACE, then you can get more information
>> >> relevant to MMC.
>> >> Could you also share log after enabled MMC_TRACE?
>> >>
>> >> Best Regards,
>> >> Jaehoon Chung
>> >>
>> >>>
>> >>> U-Boot >mmc dev 2
>> >>> blk_find_device: if_type=6, devnum=2: usdhc@02198000.blk, 6, 2
>> >>> ofnode_read_u32: vmmc-supply: 0x33 (51)
>> >>> ofnode_read_u32: vqmmc-supply: 0x33 (51)
>> >>> clock is disabled (0Hz)
>> >>> fixed_regulator_set_enable: dev='3p3v', enable=1, delay=0, has_gpio=0
>> >>> clock is enabled (400000Hz)
>> >>> Command failed, result=1
>> >>> U-Boot >
>> >>>
>> >>> and after this command, any attempt to interact with the emmc (e.g.
>> fatls
>> >>> mmc 2:1 ) ends with failure.
>> >>>
>> >>> To enable the DDR mode, all I did was define the macro
>> >>> CONFIG_SYS_FSL_ESDHC_HAS_DDR_MODE in the header of my board.
>> >>>
>> >>> Any help is greatly appreciated !
>> >>>
>> >>> --
>> >>>
>> >>> Abder,
>> >>>
>> >>
>> >>
>> >
>>
>>